This file is indexed.

/usr/share/perl5/VM/EC2.pm is in libvm-ec2-perl 1.28-2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
package VM::EC2;

=head1 NAME

VM::EC2 - Perl interface to Amazon EC2, Virtual Private Cloud, Elastic Load Balancing, Autoscaling, and Relational Database services

=head1 SYNOPSIS

NOTE: For information on AWS's VPC, load balancing, autoscaling and relational
databases services, see L<VM::EC2::VPC>, L<VM::EC2::ELB>,
L<VM::EC2::REST::autoscaling>, and
L<VM::EC2::REST::relational_database_service>

 # set environment variables EC2_ACCESS_KEY, EC2_SECRET_KEY and/or EC2_URL
 # to fill in arguments automatically

 ## IMAGE AND INSTANCE MANAGEMENT
 # get new EC2 object
 my $ec2 = VM::EC2->new(-access_key => 'access key id',
                        -secret_key => 'aws_secret_key',
                        -endpoint   => 'http://ec2.amazonaws.com');

 # fetch an image by its ID
 my $image = $ec2->describe_images('ami-12345');

 # get some information about the image
 my $architecture = $image->architecture;
 my $description  = $image->description;
 my @devices      = $image->blockDeviceMapping;
 for my $d (@devices) {
    print $d->deviceName,"\n";
    print $d->snapshotId,"\n";
    print $d->volumeSize,"\n";
 }

 # run two instances
 my @instances = $image->run_instances(-key_name      =>'My_key',
                                       -security_group=>'default',
                                       -min_count     =>2,
                                       -instance_type => 't1.micro')
           or die $ec2->error_str;

 # wait for both instances to reach "running" or other terminal state
 $ec2->wait_for_instances(@instances);

 # print out both instance's current state and DNS name
 for my $i (@instances) {
    my $status = $i->current_status;
    my $dns    = $i->dnsName;
    print "$i: [$status] $dns\n";
 }

 # tag both instances with Role "server"
 foreach (@instances) {$_->add_tag(Role=>'server');

 # stop both instances
 foreach (@instances) {$_->stop}
 
 # find instances tagged with Role=Server that are
 # stopped, change the user data and restart.
 @instances = $ec2->describe_instances({'tag:Role'       => 'Server',
                                        'instance-state-name' => 'stopped'});
 for my $i (@instances) {
    $i->userData('Secure-mode: off');
    $i->start or warn "Couldn't start $i: ",$i->error_str;
 }

 # create an image from both instance, tag them, and make
 # them public
 for my $i (@instances) {
     my $img = $i->create_image("Autoimage from $i","Test image");
     $img->add_tags(Name  => "Autoimage from $i",
                    Role  => 'Server',
                    Status=> 'Production');
     $img->make_public(1);
 }

 ## KEY MANAGEMENT

 # retrieve the name and fingerprint of the first instance's 
 # key pair
 my $kp = $instances[0]->keyPair;
 print $instances[0], ": keypair $kp=",$kp->fingerprint,"\n";

 # create a new key pair
 $kp = $ec2->create_key_pair('My Key');
 
 # get the private key from this key pair and write it to a disk file
 # in ssh-compatible format
 my $private_key = $kp->private_key;
 open (my $f,'>MyKeypair.rsa') or die $!;
 print $f $private_key;
 close $f;

 # Import a preexisting SSH key
 my $public_key = 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8o...';
 $key = $ec2->import_key_pair('NewKey',$public_key);

 ## SECURITY GROUPS AND FIREWALL RULES
 # Create a new security group
 my $group = $ec2->create_security_group(-name        => 'NewGroup',
                                         -description => 'example');

 # Add a firewall rule 
 $group->authorize_incoming(-protocol  => 'tcp',
                            -port      => 80,
                            -source_ip => ['192.168.2.0/24','192.168.2.1/24'});

 # Write rules back to Amazon
 $group->update;

 # Print current firewall rules
 print join ("\n",$group->ipPermissions),"\n";

 ## VOLUME && SNAPSHOT MANAGEMENT

 # find existing volumes that are available
 my @volumes = $ec2->describe_volumes({status=>'available'});

 # back 'em all up to snapshots
 foreach (@volumes) {$_->snapshot('Backup on '.localtime)}

 # find a stopped instance in first volume's availability zone and 
 # attach the volume to the instance using /dev/sdg
 my $vol  = $volumes[0];
 my $zone = $vol->availabilityZone;
 @instances = $ec2->describe_instances({'availability-zone'=> $zone,
                                        'run-state-name'   => $stopped);
 $instances[0]->attach_volume($vol=>'/dev/sdg') if @instances;

 # create a new 20 gig volume
 $vol = $ec2->create_volume(-availability_zone=> 'us-east-1a',
                            -size             =>  20);
 $ec2->wait_for_volumes($vol);
 print "Volume $vol is ready!\n" if $vol->current_status eq 'available';

 # create a new elastic address and associate it with an instance
 my $address = $ec2->allocate_address();
 $instances[0]->associate_address($address);

=head1 DESCRIPTION

This is an interface to the 2014-05-01 version of the Amazon AWS API
(http://aws.amazon.com/ec2). It was written provide access to the new
tag and metadata interface that is not currently supported by
Net::Amazon::EC2, as well as to provide developers with an extension
mechanism for the API. This library will also support the Open Stack
open source cloud (http://www.openstack.org/).

The main interface is the VM::EC2 object, which provides methods for
interrogating the Amazon EC2, launching instances, and managing
instance lifecycle. These methods return the following major object
classes which act as specialized interfaces to AWS:

 VM::EC2::BlockDevice               -- A block device
 VM::EC2::BlockDevice::Attachment   -- Attachment of a block device to an EC2 instance
 VM::EC2::BlockDevice::EBS          -- An elastic block device
 VM::EC2::BlockDevice::Mapping      -- Mapping of a virtual storage device to a block device
 VM::EC2::BlockDevice::Mapping::EBS -- Mapping of a virtual storage device to an EBS block device
 VM::EC2::Group                     -- Security groups
 VM::EC2::Image                     -- Amazon Machine Images (AMIs)
 VM::EC2::Instance                  -- Virtual machine instances
 VM::EC2::Instance::Metadata        -- Access to runtime metadata from running instances
 VM::EC2::Region                    -- Availability regions
 VM::EC2::Snapshot                  -- EBS snapshots
 VM::EC2::Tag                       -- Metadata tags

In addition, there is a high level interface for interacting with EC2
servers and volumes, including file transfer and remote shell facilities:

  VM::EC2::Staging::Manager         -- Manage a set of servers and volumes.
  VM::EC2::Staging::Server          -- A staging server, with remote shell and file transfer
                                        facilities.
  VM::EC2::Staging::Volume          -- A staging volume with the ability to copy itself between
                                        availability zones and regions.

and a few specialty classes:

  VM::EC2::Security::Token          -- Temporary security tokens for granting EC2 access to
                                        non-AWS account holders.
  VM::EC2::Security::Credentials    -- Credentials for use by temporary account holders.
  VM::EC2::Security::Policy         -- Policies that restrict what temporary account holders
                                        can do with EC2 resources.
  VM::EC2::Security::FederatedUser  -- Account name information for temporary account holders.

Lastly, there are several utility classes:

 VM::EC2::Generic                   -- Base class for all AWS objects
 VM::EC2::Error                     -- Error messages
 VM::EC2::Dispatch                  -- Maps AWS XML responses onto perl object classes
 VM::EC2::ReservationSet            -- Hidden class used for describe_instances() request;
                                        The reservation Ids are copied into the Instance
                                         object.

There is also a high-level API called "VM::EC2::Staging::Manager" for
managing groups of staging servers and volumes which greatly
simplifies the task of creating and updating instances that mount
multiple volumes. The API also provides a one-line command for
migrating EBS-backed AMIs from one zone to another. See
L<VM::EC2::Staging::Manager>.

The interface provided by these modules is based on that described at
http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/. The
following caveats apply:

 1) Not all of the Amazon API is currently implemented. Specifically,
    a handful calls dealing with cluster management and VM importing
    are missing.  See L</MISSING METHODS> for a list of all the
    unimplemented API calls. Volunteers to fill in these gaps are
    most welcome!

 2) For consistency with common Perl coding practices, method calls
    are lowercase and words in long method names are separated by
    underscores. The Amazon API prefers mixed case.  So in the Amazon
    API the call to fetch instance information is "DescribeInstances",
    while in VM::EC2, the method is "describe_instances". To avoid
    annoyance, if you use the mixed case form for a method name, the
    Perl autoloader will automatically translate it to underscores for
    you, and vice-versa; this means you can call either
    $ec2->describe_instances() or $ec2->DescribeInstances().

 3) Named arguments passed to methods are all lowercase, use
    underscores to separate words and start with hyphens.
    In other words, if the AWS API calls for an argument named
    "InstanceId" to be passed to the "DescribeInstances" call, then
    the corresponding Perl function will look like:

         $instance = $ec2->describe_instances(-instance_id=>'i-12345')

    In most cases automatic case translation will be performed for you
    on arguments. So in the previous example, you could use
    -InstanceId as well as -instance_id. The exception
    is when an absurdly long argument name was replaced with an 
    abbreviated one as described below. In this case, you must use
    the documented argument name.

    In a small number of cases, when the parameter name was absurdly
    long, it has been abbreviated. For example, the
    "Placement.AvailabilityZone" parameter has been represented as
    -placement_zone and not -placement_availability_zone. See the
    documentation for these cases.

 4) For each of the describe_foo() methods (where "foo" is a type of
    resource such as "instance"), you can fetch the resource by using
    their IDs either with the long form:

          $ec2->describe_foo(-foo_id=>['a','b','c']),

    or a shortcut form: 

          $ec2->describe_foo('a','b','c');

    Both forms are listed in the headings in the documentation.

 5) When the API calls for a list of arguments named Arg.1, Arg.2,
    then the Perl interface allows you to use an anonymous array for
    the consecutive values. For example to call describe_instances()
    with multiple instance IDs, use:

       @i = $ec2->describe_instances(-instance_id=>['i-12345','i-87654'])

 6) All Filter arguments are represented as a -filter argument whose value is
    an anonymous hash:

       @i = $ec2->describe_instances(-filter=>{architecture=>'i386',
                                               'tag:Name'  =>'WebServer'})

    If there are no other arguments you wish to pass, you can omit the
    -filter argument and just pass a hashref:

       @i = $ec2->describe_instances({architecture=>'i386',
                                      'tag:Name'  =>'WebServer'})

    For any filter, you may represent multiple OR arguments as an arrayref:

      @i = $ec2->describe-instances({'instance-state-name'=>['stopped','terminated']})

    When adding or removing tags, the -tag argument uses the same syntax.

 7) The tagnames of each XML object returned from AWS are converted into methods
    with the same name and typography. So the <privateIpAddress> tag in a
    DescribeInstancesResponse, becomes:

           $instance->privateIpAddress

    You can also use the more Perlish form -- this is equivalent:

          $instance->private_ip_address

    Methods that correspond to complex objects in the XML hierarchy
    return the appropriate Perl object. For example, an instance's
    blockDeviceMapping() method returns an object of type
    VM::EC2::BlockDevice::Mapping.

    All objects have a fields() method that will return the XML
    tagnames listed in the AWS specifications.

      @fields = sort $instance->fields;
      # 'amiLaunchIndex', 'architecture', 'blockDeviceMapping', ...

 8) Whenever an object has a unique ID, string overloading is used so that 
    the object interpolates the ID into the string. For example, when you
    print a VM::EC2::Volume object, or use it in another string context,
    then it will appear as the string "vol-123456". Nevertheless, it will
    continue to be usable for method calls.

         ($v) = $ec2->describe_volumes();
         print $v,"\n";                 # prints as "vol-123456"
         $zone = $v->availabilityZone;  # acts like an object

 9) Many objects have convenience methods that invoke the AWS API on your
    behalf. For example, instance objects have a current_status() method that returns
    the run status of the object, as well as start(), stop() and terminate()
    methods that control the instance's lifecycle.

         if ($instance->current_status eq 'running') {
             $instance->stop;
         }

 10) Calls to AWS that have failed for one reason or another (invalid
    arguments, communications problems, service interruptions) will
    return undef and set the VM::EC2->is_error() method to true. The
    error message and its code can then be recovered by calling
    VM::EC2->error.

      $i = $ec2->describe_instance('i-123456');
      unless ($i) {
          warn 'Got no instance. Message was: ',$ec2->error;
      }

    You may also elect to raise an exception when an error occurs.
    See the new() method for details.

=head1 ASYNCHRONOUS CALLS

As of version 1.24, VM::EC2 supports asynchronous calls to AWS using
AnyEvent::HTTP. This allows you to make multiple calls in parallel for
a significant improvement in performance.

In asynchronous mode, VM::EC2 calls that ordinarily wait for AWS to
respond and then return objects corresponding to EC2 instances,
volumes, images, and so forth, will instead immediately return an
AnyEvent condition variable. You can retrieve the result of the call
by calling the condition variable's recv() method, or by setting a
callback to be executed when the call is complete.

To make an asynchronous call, you can set the global variable
$VM::EC2::ASYNC to a true value

Here is an example of a normal synchronous call:
  
 my @instances = $ec2->describe_instances();

Here is the asynchronous version initiated after setting
$VM::EC2::ASYNC (using a local block to limit its effects).

 {
    local $VM::EC2::ASYNC=1;
    my $cv = $ec2->describe_instances();   # returns immediately
    my @instances = $cv->recv;
 }

In case of an error recv() will return undef and the error object can
be recovered using the condition variable's error() method (this is an
enhancement over AnyEvent's standard condition variable class):

 my @instances = $cv->recv 
    or die "No instances found! error = ",$cv->error();

You may attach a callback CODE reference to the condition variable using
its cb() method, in which case the callback will be invoked when the
APi call is complete. The callback will be invoked with a single
argument consisting of the condition variable. Ordinarily you will
call recv() on the variable and then do something with the result:

 {
   local $VM::EC2::ASYNC=1;
   my $cv = $ec2->describe_instances();
   $cv->cb(sub {my $v = shift;
                my @i = $v->recv;
                print "instances = @i\n"; 
                });
  }

For callbacks to be invoked, someone must be run an event loop
using one of the event frameworks that AnyEvent supports (e.g. Coro,
Tk or Gtk). Alternately, you may simply run:

 AnyEvent->condvar->recv();
 
If $VM::EC2::ASYNC is false, you can issue a single asynchronous call
by appending "_async" to the name of the method call. Similarly, if
$VM::EC2::ASYNC is true, you can make a single normal synchrous call
by appending "_sync" to the method name.

For example, this is equivalent to the above:

 my $cv = $ec2->describe_instances_async();  # returns immediately
 my @instances = $cv->recv;

You may stack multiple asynchronous calls on top of one another. When
you call recv() on any of the returned condition variables, they will
all run in parallel. Hence the three calls will take no longer than
the longest individual one:

 my $cv1 = $ec2->describe_instances_async({'instance-state-name'=>'running'});
 my $cv2 = $ec2->describe_instances_async({'instance-state-name'=>'stopped'});
 my @running = $cv1->recv;
 my @stopped = $cv2->recv;

Same thing with callbacks:

 my (@running,@stopped);
 my $cv1 = $ec2->describe_instances_async({'instance-state-name'=>'running'});
 $cv1->cb(sub {@running = shift->recv});

 my $cv2 = $ec2->describe_instances_async({'instance-state-name'=>'stopped'});
 $cv1->cb(sub {@stopped = shift->recv});

 AnyEvent->condvar->recv;

And here it is using a group conditional variable to block until all
pending describe_instances() requests have completed:

 my %instances;
 my $group = AnyEvent->condvar;
 $group->begin;
 for my $state (qw(pending running stopping stopped)) {
    $group->begin;
    my $cv = $ec2->describe_instances_async({'instance-state-name'=>$state});
    $cv->cb(sub {my @i = shift->recv;
                 $instances{$state}=\@i;
                 $group->end});
 }
 $group->recv;
 # when we get here %instances will be populated by all instances,
 # sorted by their state.

If this looks mysterious, please consult L<AnyEvent> for full
documentation and examples.

Lastly, be advised that some of the objects returned by calls to
VM::EC2, such as the VM::EC2::Instance object, will make their own
calls into VM::EC2 for certain methods. Some of these methods will
block (be synchronous) of necessity, even if you have set
$VM::EC2::ASYNC. For example, the instance object's current_status()
method must block in order to update the object and return the current
status. Other object methods may behave unpredictably in async
mode. Caveat emptor!

=head1 API GROUPS

The extensive (and growing) Amazon API has many calls that you may
never need. To avoid the performance overhead of loading the
interfaces to all these calls, you may use Perl's import mechanism to
load only those modules you care about. By default, all methods are
loaded.

Loading is controlled by the "use" import list, and follows the
conventions described in the Exporter module:

 use VM::EC2;                     # load all methods!

 use VM::EC2 'key','elastic_ip';  # load Key Pair and Elastic IP
				  # methods only

 use VM::EC2 ':standard';         # load all the standard methods

 use VM::EC2 ':standard','!key';  # load standard methods but not Key Pair

Related API calls are grouped together using the scheme described at
http://docs.aws.amazon.com/AWSEC2/latest/APIReference/OperationList-query.html. The
modules that define the API calls can be found in VM/EC2/REST/; you
can read their documentation by running perldoc VM::EC2::REST::"name
of module":

 perldoc VM::EC2::REST::elastic_ip

The groups that you can import are as follows:
 
 :standard => ami, ebs, elastic_ip, instance, keys, general,
              monitoring, tag, security_group, security_token, zone

 :vpc      => customer_gateway, dhcp, elastic_network_interface, 
              private_ip, internet_gateway, network_acl, route_table,
              vpc, vpn, vpn_gateway

 :misc     => devpay, monitoring, reserved_instance,
              spot_instance, vm_export, vm_import, windows

 :scaling  => elastic_load_balancer,autoscaling

 :hpc      => placement_group

 :all      => :standard, :vpn, :misc

 :DEFAULT  => :all

The individual modules are:

 ami               -- Control Amazon Machine Images
 autoscaling       -- Control autoscaling
 customer_gateway  -- VPC/VPN gateways
 devpay            -- DevPay API
 dhcp              -- VPC DHCP options
 ebs               -- Elastic Block Store volumes & snapshots
 elastic_ip        -- Elastic IP addresses
 elastic_load_balancer -- The Elastic Load Balancer service
 elastic_network_interface -- VPC Elastic Network Interfaces
 general           -- Get console output and account attributes
 instance          -- Control EC2 instances
 internet_gateway  -- VPC connections to the internet
 keys              -- Manage SSH keypairs
 monitoring        -- Control instance monitoring
 network_acl       -- Control VPC network access control lists
 placement_group   -- Control the placement of HPC instances
 private_ip        -- VPC private IP addresses
 reserved_instance -- Reserve instances and view reservations
 route_table       -- VPC network routing
 security_group    -- Security groups for VPCs and normal instances
 security_token    -- Temporary credentials for use with IAM roles
 spot_instance     -- Request and manage spot instances
 subnet            -- VPC subnets
 tag               -- Create and interrogate resource tags.
 vm_export         -- Export VMs
 vm_import         -- Import VMs
 vpc               -- Create and manipulate virtual private clouds
 vpn_gateway       -- Create and manipulate VPN gateways within VPCs
 vpn               -- Create and manipulate VPNs within VPCs
 windows           -- Windows operating system-specific API calls.
 zone              -- Interrogate availability zones
  
=head1 EXAMPLE SCRIPT

The script sync_to_snapshot.pl, distributed with this module,
illustrates a relatively complex set of steps on EC2 that does
something useful. Given a list of directories or files on the local
filesystem it copies the files into an EBS snapshot with the desired
name by executing the following steps:

1. Provisions a new EBS volume on EC2 large enough to hold the data.

2. Spins up a staging instance to manage the network transfer of data
from the local machine to the staging volume.

3. Creates a temporary ssh keypair and a security group that allows an
rsync-over-ssh.

4. Formats and mounts the volume if necessary.

5. Initiates an rsync-over-ssh for the designated files and
directories.

6. Unmounts and snapshots the volume.

7. Cleans up.

If a snapshot of the same name already exists, then it is used to
create the staging volume, enabling network-efficient synchronization
of the files. A snapshot tag named "Version" is incremented each time
you synchronize.

=head1 CORE METHODS

This section describes the VM::EC2 constructor, accessor methods, and
methods relevant to error handling.

=cut

use strict;

use VM::EC2::Dispatch;
use VM::EC2::ParmParser;
eval "require AWS::Signature4"; # optional

use MIME::Base64 qw(encode_base64 decode_base64);
use Digest::SHA qw(hmac_sha256 sha1_hex sha256_hex);
use POSIX 'strftime';
use URI;
use URI::Escape;
use AnyEvent;
use AnyEvent::HTTP;
use AnyEvent::CacheDNS ':register';
use HTTP::Request::Common;
use VM::EC2::Error;
use Carp 'croak','carp';
use JSON;

our $VERSION = '1.28';
our $AUTOLOAD;
our @CARP_NOT = qw(VM::EC2::Image    VM::EC2::Volume
                   VM::EC2::Snapshot VM::EC2::Instance
                   VM::EC2::ReservedInstance);
our $ASYNC;

# hard-coded timeout for several wait_for_terminal_state() calls.
use constant WAIT_FOR_TIMEOUT => 600;

sub AUTOLOAD {
    my $self = shift;
    my ($pack,$func_name) = $AUTOLOAD=~/(.+)::([^:]+)$/;
    return if $func_name eq 'DESTROY';
    my $proper = VM::EC2->canonicalize($func_name);
    $proper =~ s/^-//;

    my $async;
    if ($proper =~ /^(\w+)_(a?sync)$/i) {
	$proper = $1;
	$async  = $2 eq 'async' ? 1 : 0;
    }

    if ($self->can($proper)) {
	my $local = defined $async ? "local \$ASYNC=$async;" : '';
	eval "sub $pack\:\:$func_name {$local shift->$proper(\@_)}; 1" or die $@;
	$self->$func_name(@_);
    } 

    else {
	croak "Can't locate object method \"$func_name\" via package \"$pack\"";
    }
}

use constant import_tags => {
    ':standard' => [qw(instance elastic_ip ebs ami keys monitoring zone general tag security_group security_token)],
    ':vpc'      => [qw(customer_gateway dhcp elastic_network_interface private_ip 
                       internet_gateway network_acl route_table subnet vpc vpn vpn_gateway)],
    ':hpc'      => ['placement_group'],
    ':scaling'  => ['elastic_load_balancer','autoscaling'],
    ':elb'      => ['elastic_load_balancer'],
    ':rds'      => ['relational_database_service'],
    ':misc'     => ['devpay','reserved_instance', 'spot_instance','vm_export','vm_import','windows'],
    ':all'      => [qw(:standard :vpc :hpc :scaling :misc)],
    ':DEFAULT'  => [':all'],
};

# e.g. use VM::EC2 ':default','!ami';
sub import {
    my $self = shift;
    my @args = @_;
    @args    = ':DEFAULT' unless @args;
    while (1) {
	my @processed = map {/^:/ && import_tags->{$_} ? @{import_tags->{$_}} : $_ } @args;
	last if "@processed" eq  "@args";  # no more expansion needed
	@args = @processed;
    }
    my (%excluded,%included);
    foreach (@args) {
	if (/^!(\S+)/) {
	    $excluded{$1}++ ;
	    $_ = $1;
	}
    }
    foreach (@args) {
	next unless /^\S/;
	next if $excluded{$_};
	next if $included{$_}++;
	croak "'$_' is not a valid import tag" if /^[!:]/;
	next if $INC{"VM/EC2/REST/$_.pm"};
	my $class = "VM::EC2::REST::$_";
	eval "require $class; 1" or die $@;
    }
}

=head2 $ec2 = VM::EC2->new(-access_key=>$id,-secret_key=>$key,-endpoint=>$url)

Create a new Amazon access object. Required arguments are:

 -access_key   Access ID for an authorized user

 -secret_key   Secret key corresponding to the Access ID

 -security_token Temporary security token obtained through a call to the
               AWS Security Token Service

 -endpoint     The URL for making API requests

 -region       The region to receive the API requests

 -raise_error  If true, throw an exception.

 -print_error  If true, print errors to STDERR.

One or more of -access_key or -secret_key can be omitted if the
environment variables EC2_ACCESS_KEY and EC2_SECRET_KEY are
defined. If no endpoint is specified, then the environment variable
EC2_URL is consulted; otherwise the generic endpoint
http://ec2.amazonaws.com/ is used. You can also select the endpoint by
specifying one of the Amazon regions, such as "us-west-2", with the
-region argument. The endpoint specified by -region will override
-endpoint.

-security_token is used in conjunction with temporary security tokens
returned by $ec2->get_federation_token() and $ec2->get_session_token()
to grant restricted, time-limited access to some or all your EC2
resources to users who do not have access to your account. If you pass
either a VM::EC2::Security::Token object, or the
VM::EC2::Security::Credentials object contained within the token
object, then new() does not need the -access_key or -secret_key
arguments. You may also pass a session token string scalar to
-security_token, in which case you must also pass the access key ID
and secret keys generated at the same time the session token was
created. See
http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/UsingIAM.html
and L</AWS SECURITY TOKENS>.

To use an Open Stack cloud, please provide the appropriate endpoint
URL.

By default, when the Amazon API reports an error, such as attempting
to perform an invalid operation on an instance, the corresponding
method will return empty and the error message can be recovered from
$ec2->error(). However, if you pass -raise_error=>1 to new(), the module
will instead raise a fatal error, which you can trap with eval{} and
report with $@:

  eval {
     $ec2->some_dangerous_operation();
     $ec2->another_dangerous_operation();
  };
  print STDERR "something bad happened: $@" if $@;

The error object can be retrieved with $ec2->error() as before.

=cut

sub new {
    my $self = shift;
    my %args = @_;

    my ($id,$secret,$token);
    if (ref $args{-security_token} && $args{-security_token}->can('access_key_id')) {
	$id     = $args{-security_token}->accessKeyId;
	$secret = $args{-security_token}->secretAccessKey;
	$token  = $args{-security_token}->sessionToken;
    }

    $id           ||= $args{-access_key} || $ENV{EC2_ACCESS_KEY}
                      or croak "Please provide -access_key parameter or define environment variable EC2_ACCESS_KEY";
    $secret       ||= $args{-secret_key} || $ENV{EC2_SECRET_KEY}
                      or croak "Please provide -secret_key or define environment variable EC2_SECRET_KEY";
    $token        ||= $args{-security_token};

    my $endpoint_url = $args{-endpoint}   || $ENV{EC2_URL} || 'https://ec2.amazonaws.com/';
    $endpoint_url   .= '/'                      unless $endpoint_url =~ m!/$!;
    $endpoint_url    = "https://".$endpoint_url unless $endpoint_url =~ m!https?://!;

    my $raise_error  = $args{-raise_error};
    my $print_error  = $args{-print_error};
    my $obj = bless {
	id              => $id,
	secret          => $secret,
	security_token  => $token,
	endpoint        => $endpoint_url,
	idempotent_seed => sha1_hex(rand()),
	raise_error     => $raise_error,
	print_error     => $print_error,
    },ref $self || $self;

    if ($args{-region}) {
	$self->import('zone');
	my $region   = eval{$obj->describe_regions($args{-region})};
	my $endpoint = $region ? $region->regionEndpoint :"ec2.$args{-region}.amazonaws.com";
	$obj->endpoint($endpoint);
    }

    return $obj;
}

sub _region {
    my $self = shift;
    my $endpoint = $self->endpoint || return 'us-east-1';
    my ($region) = $endpoint =~ /([^.]+)\.amazonaws\.com/;
    return $region || 'us-east-1';
}

=head2 $access_key = $ec2->access_key([$new_access_key])

Get or set the ACCESS KEY. In this and all similar get/set methods,
call the method with no arguments to get the current value, and with a
single argument to change the value:

 $current_key = $ec2->access_key;
 $ec2->access_key('XYZZY');

In the case of setting the value, these methods will return the old
value as their result:

 $old_key = $ec2->access_key($new_key);

=cut

sub access_key {shift->id(@_)}

sub id       { 
    my $self = shift;
    my $d    = $self->{id};
    $self->{id} = shift if @_;
    $d;
}

=head2 $secret = $ec2->secret([$new_secret])

Get or set the SECRET KEY

=cut

sub secret   {
    my $self = shift;
    my $d    = $self->{secret};
    $self->{secret} = shift if @_;
    $d;
}

=head2 $secret = $ec2->security_token([$new_token])

Get or set the temporary security token. See L</AWS SECURITY TOKENS>.

=cut

sub security_token   {
    my $self = shift;
    my $d    = $self->{security_token};
    $self->{security_token} = shift if @_;
    $d;
}

=head2 $endpoint = $ec2->endpoint([$new_endpoint])

Get or set the ENDPOINT URL.

=cut

sub endpoint { 
    my $self = shift;
    my $d    = $self->{endpoint};
    if (@_) {
	my $new_endpoint = shift;
	$new_endpoint    = 'https://'.$new_endpoint
	    unless $new_endpoint =~ /^https?:/;
	$self->{endpoint} = $new_endpoint;
    }
    $d;
 }

=head2 $region = $ec2->region([$new_region])

Get or set the EC2 region manipulated by this module. This has the side effect
of changing the endpoint.

=cut

sub region { 
    my $self = shift;

    my $d    = $self->{endpoint};
    $d       =~ s!^https?://!!;
    $d       =~ s!/$!!;

    $self->import('zone');
    my @regions = $self->describe_regions;
    my ($current_region) = grep {$_->regionEndpoint eq $d} @regions;

    if (@_) {
	my $new_region = shift;
	my ($region) = grep {/$new_region/} @regions;
	$region or croak "unknown region $new_region";
	$self->endpoint($region->regionEndpoint);
    }
    return $current_region;
}

=head2 $ec2->raise_error($boolean)

Change the handling of error conditions. Pass a true value to cause
Amazon API errors to raise a fatal error. Pass false to make methods
return undef. In either case, you can detect the error condition
by calling is_error() and fetch the error message using error(). This
method will also return the current state of the raise error flag.

=cut

sub raise_error {
    my $self = shift;
    my $d    = $self->{raise_error};
    $self->{raise_error} = shift if @_;
    $d;
}

=head2 $ec2->print_error($boolean)

Change the handling of error conditions. Pass a true value to cause
Amazon API errors to print error messages to STDERR. Pass false to
cancel this behavior.

=cut

sub print_error {
    my $self = shift;
    my $d    = $self->{print_error};
    $self->{print_error} = shift if @_;
    $d;
}

=head2 $boolean = $ec2->is_error

If a method fails, it will return undef. However, some methods, such
as describe_images(), will also return undef if no resources matches
your search criteria. Call is_error() to distinguish the two
eventualities:

  @images = $ec2->describe_images(-owner=>'29731912785');
  unless (@images) {
      die "Error: ",$ec2->error if $ec2->is_error;
      print "No appropriate images found\n";
  }

=cut

sub is_error {
    defined shift->error();
}

=head2 $err = $ec2->error

If the most recently-executed method failed, $ec2->error() will return
the error code and other descriptive information. This method will
return undef if the most recently executed method was successful.

The returned object is actually an AWS::Error object, which
has two methods named code() and message(). If used in a string
context, its operator overloading returns the composite string
"$message [$code]".

=cut

sub error {
    my $self = shift;
    my $d    = $self->{error};
    $self->{error} = shift if @_;
    $d;
}

=head2 $err = $ec2->error_str

Same as error() except it returns the string representation, not the
object. This works better in debuggers and exception handlers.

=cut

sub error_str { 
    my $e = shift->{error};
    $e ||= '';
    return "$e";
}

=head2 $account_id = $ec2->account_id

Looks up the account ID corresponding to the credentials provided when
the VM::EC2 instance was created. The way this is done is to fetch the
"default" security group, which is guaranteed to exist, and then
return its groupId field. The result is cached so that subsequent
accesses are fast.

=head2 $account_id = $ec2->userId

Same as above, for convenience.

=cut

sub account_id {
    my $self = shift;
    return $self->{account_id} if exists $self->{account_id};
    my $sg   = $self->describe_security_groups(-group_name=>'default') or return;
    return $self->{account_id} ||= $sg->ownerId;
}

sub userId { shift->account_id }

=head2 $new_ec2 = $ec2->clone

This method creates an identical copy of the EC2 object. It is used
occasionally internally for creating an EC2 object in a different AWS
region:

 $singapore = $ec2->clone;
 $singapore->region('ap-souteast-1');

=cut

sub clone {
    my $self = shift;
    my %contents = %$self;
    return bless \%contents,ref $self;
}

=head1 INSTANCES

Load the 'instances' module to bring in methods for interrogating,
launching and manipulating EC2 instances. This module is part of
the ':standard' API group. The methods are described in detail in
L<VM::EC2::REST::instance>. Briefly:

 @i = $ec2->describe_instances(-instance_id=>\@ids,-filter=>\%filters)
 @i = $ec2->run_instances(-image_id=>$id,%other_args)
 @s = $ec2->start_instances(-instance_id=>\@instance_ids)
 @s = $ec2->stop_instances(-instance_id=>\@instance_ids,-force=>1)
 @s = $ec2->reboot_instances(-instance_id=>\@instance_ids)
 $b = $ec2->confirm_product_instance($instance_id,$product_code)
 $m = $ec2->instance_metadata
 @d = $ec2->describe_instance_attribute($instance_id,$attribute)
 $b = $ec2->modify_instance_attribute($instance_id,-$attribute_name=>$value)
 $b = $ec2->reset_instance_attribute($instance_id,$attribute)
 @s = $ec2->describe_instance_status(-instance_id=>\@ids,-filter=>\%filters,%other_args);

=head1 VOLUMES

Load the 'ebs' module to bring in methods specific for elastic block
storage volumes and snapshots. This module is part of the ':standard'
API group. The methods are described in detail in
L<VM::EC2::REST::ebs>. Briefly:

 @v = $ec2->describe_volumes(-volume_id=>\@ids,-filter=>\%filters)
 $v = $ec2->create_volume(%args)
 $b = $ec2->delete_volume($volume_id)
 $a = $ec2->attach_volume($volume_id,$instance_id,$device)
 $a = $ec2->detach_volume($volume_id)
 $ec2->wait_for_attachments(@attachment)
 @v = $ec2->describe_volume_status(-volume_id=>\@ids,-filter=>\%filters)
 $ec2->wait_for_volumes(@volumes)
 @d = $ec2->describe_volume_attribute($volume_id,$attribute)
 $b = $ec2->enable_volume_io(-volume_id=>$volume_id)
 @s = $ec2->describe_snapshots(-snapshot_id=>\@ids,%other_args)
 @d = $ec2->describe_snapshot_attribute($snapshot_id,$attribute)
 $b = $ec2->modify_snapshot_attribute($snapshot_id,-$argument=>$value)
 $b = $ec2->reset_snapshot_attribute($snapshot_id,$attribute)
 $s = $ec2->create_snapshot(-volume_id=>$vol,-description=>$desc)
 $b = $ec2->delete_snapshot($snapshot_id) 
 $s = $ec2->copy_snapshot(-source_region=>$region,-source_snapshot_id=>$id,-description=>$desc)
 $ec2->wait_for_snapshots(@snapshots)

=head1 AMAZON MACHINE IMAGES

Load the 'ami' module to bring in methods for creating and
manipulating Amazon Machine Images. This module is part of the
':standard" group. Full details are in L<VM::EC2::REST::ami>. Briefly:

 @i = $ec2->describe_images(@image_ids)
 $i = $ec2->create_image(-instance_id=>$id,-name=>$name,%other_args)
 $i = $ec2->register_image(-name=>$name,%other_args)
 $r = $ec2->deregister_image($image_id)
 @d = $ec2->describe_image_attribute($image_id,$attribute)
 $b = $ec2->modify_image_attribute($image_id,-$attribute_name=>$value)
 $b = $ec2->reset_image_attribute($image_id,$attribute_name)

=head1 KEYS

Load the 'keys' module to bring in methods for creating and
manipulating SSH keypairs. This module is loaded with the ':standard'
group and documented in L<VM::EC2::REST::keys>.

 @k = $ec2->describe_key_pairs(@names);
 $k = $ec2->create_key_pair($name)
 $k = $ec2->import_key_pair($name,$public_key) 
 $b = $ec2->delete_key_pair($name)

=head1 TAGS

The methods in this module (loaded with ':standard') allow you to
create, delete and fetch resource tags. You may find that you rarely
need to use these methods directly because every object produced by
VM::EC2 supports a simple tag interface:
 
  $object = $ec2->describe_volumes(-volume_id=>'vol-12345'); # e.g.
  $tags = $object->tags();
  $name = $tags->{Name};
  $object->add_tags(Role => 'Web Server', Status=>'development);
  $object->delete_tags(Name=>undef);

See L<VM::EC2::Generic> for a full description of the uniform object
tagging interface, and L<VM::EC2::REST::tag> for methods that allow
you to manipulate the tags on multiple objects simultaneously. The
methods defined by this module are:

 @t = $ec2->describe_tags(-filter=>\%filters);
 $b = $ec2->create_tags(-resource_id=>\@ids,-tag=>{key1=>value1...})
 $b = $ec2->delete_tags(-resource_id=>$id1,-tag=>{key1=>value1...})
 
=head1 VIRTUAL PRIVATE CLOUDS

EC2 virtual private clouds (VPCs) provide facilities for creating
tiered applications combining public and private subnetworks, and for
extending your home/corporate network into the cloud. VPC-related
methods are defined in the customer_gateway, dhcp,
elastic_network_interface, private_ip, internet_gateway, network_acl,
route_table, vpc, vpn, and vpn_gateway modules, and are loaded by
importing ':vpc'. See L<VM::EC2::REST::vpc> for an introduction.

The L<VM::EC2::VPC> and L<VM::EC2::VPC::Subnet> modules define
convenience methods that simplify working with VPC objects. This
allows for steps that typically follow each other, such as creating a
route table and associating it with a subnet, happen
automatically. For example, this series of calls creates a VPC with a
single subnet, creates an Internet gateway attached to the VPC,
associates a new route table with the subnet and then creates a
default route from the subnet to the Internet gateway:

 $vpc       = $ec2->create_vpc('10.0.0.0/16')     or die $ec2->error_str;
 $subnet1   = $vpc->create_subnet('10.0.0.0/24')  or die $vpc->error_str;
 $gateway   = $vpc->create_internet_gateway       or die $vpc->error_str;
 $routeTbl  = $subnet->create_route_table         or die $vpc->error_str;
 $routeTbl->create_route('0.0.0.0/0' => $gateway) or die $vpc->error_str;

=head1 ELASTIC LOAD BALANCERS (ELB) AND AUTOSCALING

The methods in the 'elastic_load_balancer' and 'autoscaling' modules
allow you to retrieve information about Elastic Load Balancers, create
new ELBs, and change the properties of the ELBs, as well as define
autoscaling groups and their launch configurations. These modules are
both imported by the ':scaling' import group. See
L<VM::EC2::REST::elastic_load_balancer> and
L<VM::EC2::REST::autoscaling> for descriptions of the facilities
enabled by this module.

=head1 AWS SECURITY POLICY

The VM::EC2::Security::Policy module provides a simple Identity and
Access Management (IAM) policy statement generator geared for use with
AWS security tokens (see next section). Its facilities are defined in
L<VM::EC2::Security::Token>.

=head1 AWS SECURITY TOKENS

AWS security tokens provide a way to grant temporary access to
resources in your EC2 space without giving them permanent
accounts. They also provide the foundation for mobile services and
multifactor authentication devices (MFA). These methods are defined in
'security_token', which is part of the ':standard' group. See
L<VM::EC2::REST::security_token> for details. Here is a quick example:

Here is an example:

 # on your side of the connection
 $ec2 = VM::EC2->new(...);  # as usual
 my $policy = VM::EC2::Security::Policy->new;
 $policy->allow('DescribeImages','RunInstances');
 my $token = $ec2->get_federation_token(-name     => 'TemporaryUser',
                                        -duration => 60*60*3, # 3 hrs, as seconds
                                        -policy   => $policy);
 my $serialized = $token->credentials->serialize;
 send_data_to_user_somehow($serialized);

 # on the temporary user's side of the connection
 my $serialized = get_data_somehow();
 my $token = VM::EC2::Security::Credentials->new_from_serialized($serialized);
 my $ec2   = VM::EC2->new(-security_token => $token);
 print $ec2->describe_images(-owner=>'self');

=head1 SPOT AND RESERVED INSTANCES

The 'spot_instance' and 'reserved_instance' modules allow you to
create and manipulate spot and reserved instances. They are both part
of the ':misc' import group. See L<VM::EC2::REST::spot_instance> and
L<VM::EC2::REST::reserved_instance>. For example:

 @offerings = $ec2->describe_reserved_instances_offerings(
          {'availability-zone'   => 'us-east-1a',
           'instance-type'       => 'c1.medium',
           'product-description' =>'Linux/UNIX',
           'duration'            => 31536000,  # this is 1 year
           });
 $offerings[0]->purchase(5) and print "Five reserved instances purchased\n";



=head1 WAITING FOR STATE CHANGES

VM::EC2 provides a series of methods that allow your script to wait in
an efficient manner for desired state changes in instances, volumes
and other objects. They are described in detail the individual modules
to which they apply, but in each case the method will block until each
member of a list of objects transitions to a terminal state
(e.g. "completed" in the case of a snapshot). Briefly:

 $ec2->wait_for_instances(@instances)
 $ec2->wait_for_snapshots(@snapshots) 
 $ec2->wait_for_volumes(@volumes) 
 $ec2->wait_for_attachments(@attachment)

There is also a generic version of this defined in the VM::EC2 core:

=head2 $ec2->wait_for_terminal_state(\@objects,['list','of','states'] [,$timeout])

Generic version of the last four methods. Wait for all members of the
provided list of Amazon objects instances to reach some terminal state
listed in the second argument, and then return a hash reference that
maps each object ID to its final state.

If a timeout is provided, in seconds, then the method will abort after
waiting the indicated time and return undef.

=cut

sub wait_for_terminal_state {
    my $self = shift;
    my ($objects,$terminal_states,$timeout) = @_;
    my %terminal_state = map {$_=>1} @$terminal_states;
    my %status = ();
    my @pending = grep {defined $_} @$objects; # in case we're passed an undef

    my %timers;
    my $done = $self->condvar();
    $done->begin(sub {
	my $cv = shift;
	if ($cv->error) {
	    $self->error($cv->error);
	    $cv->send();
	} else {
	    $cv->send(\%status);
	}
		 }
	);
    
    for my $obj (@pending) {
	$done->begin;
	my $timer = AnyEvent->timer(interval => 3,
				    cb       => sub {
					$obj->current_status_async->cb( 
					    sub {
						my $state = shift->recv;
						if (!$state || $terminal_state{$state}) {
						    $status{$obj} = $state;
						    $done->end;
						    undef $timers{$obj};
						}})});
	$timers{$obj} = $timer;
    }

    # timeout
    my $timeout_event;
    $timeout_event = AnyEvent->timer(after=> $timeout,
				     cb   => sub {
					 undef %timers; # cancel all timers
					 undef $timeout_event;
					 $done->error('timeout waiting for terminal state');
					 $done->end foreach @pending;
				     }) if $timeout;
    $done->end;

    return $ASYNC ? $done : $done->recv;
}

=head2 $timeout = $ec2->wait_for_timeout([$new_timeout]);

Get or change the timeout for wait_for_instances(), wait_for_attachments(),
and wait_for_volumes(). The timeout is given in seconds, and defaults to
600 (10 minutes). You can set this to 0 to wait forever.

=cut

sub wait_for_timeout {
    my $self = shift;
    $self->{wait_for_timeout} = WAIT_FOR_TIMEOUT
	unless defined $self->{wait_for_timeout};
    my $d = $self->{wait_for_timeout};
    $self->{wait_for_timeout} = shift if @_;
    return $d;
}

# ------------------------------------------------------------------------------------------

=head1 INTERNAL METHODS

These methods are used internally and are listed here without
documentation (yet).

=head2 $underscore_name = $ec2->canonicalize($mixedCaseName)

=cut

sub canonicalize {
    my $self = shift;
    my $name = shift;

    $name =~ s/^-//;
    $name    =~ s/DB/Db/g;
    $name    =~ s/AZ/Az/g;

    while ($name =~ /[A-Z][^A-Z]/) {
        $name    =~ s/(?<!^)([A-Z]*[\d]*)\.?([A-Z])/\L$1_$2/g or last;
    }
    return '-'.lc $name;
}

sub uncanonicalize {
    my $self = shift;
    my $name = shift;
    $name    =~ s/_([a-z])/\U$1/g;
    return $name;
}

=head2 $instance_id = $ec2->instance_parm(@args)

=cut

sub instance_parm {
    my $self = shift;
    my %args;
    if ($_[0] =~ /^-/) {
	%args = @_; 
    } elsif (@_ > 1) {
	%args = (-instance_id => [@_]);
    } else {
	%args = (-instance_id => shift);
    }
    my $id = $args{-instance_id};
    return ref $id && ref $id eq 'ARRAY' ? @$id : $id;
}

=head2 @arguments = $ec2->value_parm(ParameterName => \%args)

=cut

sub value_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    my $name = $self->canonicalize($argname);
    return unless exists $args->{$name} || exists $args->{"-$argname"};
    my $val = $args->{$name} || $args->{"-$argname"};
    return ("$argname.Value"=>$val);
}

=head2 @arguments = $ec2->single_parm(ParameterName => \%args)

=cut

sub single_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    my $name = $self->canonicalize($argname);
    my $val  = $args->{$name} || $args->{"-$argname"};
    defined $val or return;
    my $v = ref $val  && ref $val eq 'ARRAY' ? $val->[0] : $val;
    return ($argname=>$v);
}

=head2 @parameters = $ec2->prefix_parm($prefix, ParameterName => \%args)

=cut

sub prefix_parm {
    my $self = shift;
    my ($prefix,$argname,$args) = @_;
    my $name = $self->canonicalize($argname);
    my $val  = $args->{$name} || $args->{"-$argname"};
    defined $val or return;
    my $v = ref $val  && ref $val eq 'ARRAY' ? $val->[0] : $val;
    return ("$prefix.$argname"=>$v);
}

=head2 @arguments = $ec2->member_hash_parms(ParameterName => \%args)

Create a parameter list from a hashref or arrayref of hashes

Created specifically for the RDS ModifyDBParameterGroup parameter
'Parameters', but may be useful for other calls in the future.

ie:

The argument would be in the form:

   [
           {
                   ParameterName=>'max_user_connections',
                   ParameterValue=>24,
                   ApplyMethod=>'pending-reboot'
           },
           {
                   ParameterName=>'max_allowed_packet',
                   ParameterValue=>1024,
                   ApplyMethod=>'immediate'
           },
   ];

The resulting output would be if the argname is '-parameters':

Parameters.member.1.ParameterName => max_user_connections
Parameters.member.1.ParameterValue => 24
Parameters.member.1.ApplyMethod => pending-reboot
Parameters.member.2.ParameterName => max_allowed_packet
Parameters.member.2.ParameterValue => 1024
Parameters.member.2.ApplyMethod => immediate

=cut

sub member_hash_parms {
    my $self = shift;
    my ($argname,$args) = @_;
    my $name = $self->canonicalize($argname);

    my @params;
    if (my $arg = $args->{$name}||$args->{"-$argname"}) {
        $arg = [ $arg ] if ref $arg eq 'HASH';
        return unless ref $arg eq 'ARRAY';
        my $c = 1;
        foreach my $a (@$arg) {
            next unless ref $a eq 'HASH';
            foreach my $key (keys %$a) {
                push @params, ("$argname.member.$c.$key" => $a->{$key});
            }
            $c++;
        }
    }
    return @params;
}

=head2 @arguments = $ec2->list_parm(ParameterName => \%args)

=cut

sub list_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    return $self->_list_parm($argname,$args);
}

=head2 @parameters = $ec2->member_list_parm(ParameterName => \%args)

=cut

sub member_list_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    return $self->_list_parm($argname,$args,'member');
}

sub _list_parm {
    my $self = shift;
    my ($argname,$args,$append) = @_;
    my $name = $self->canonicalize($argname);

    my @params;
    if (my $a = $args->{$name}||$args->{"-$argname"}) {
        $argname .= ".$append" if $append;
	my $c = 1;
	for (ref $a && ref $a eq 'ARRAY' ? @$a : $a) {
	    push @params,("$argname.".$c++ => $_);
	}
    }

    return @params;
}

=head2 @arguments = $ec2->filter_parm(\%args)

=cut

sub filter_parm {
    my $self = shift;
    my $args = shift;
    return $self->key_value_parameters('Filter','Name','Value',$args);
}

=head2 @arguments = $ec2->key_value_parameters($param_name,$keyname,$valuename,\%args,$skip_undef_values)

=cut

sub key_value_parameters {
    my $self = shift;
    # e.g. 'Filter', 'Name','Value',{-filter=>{a=>b}}
    return $self->_key_value_parameters(@_);
}

=head2 @arguments = $ec2->member_key_value_parameters($param_name,$keyname,$valuename,\%args,$skip_undef_values)

=cut

sub member_key_value_parameters {
    my $self = shift;
    my ($parameter_name,$keyname,$valuename,$args,$skip_undef_values) = @_;  
    return $self->_key_value_parameters($parameter_name,$keyname,$valuename,$args,$skip_undef_values,'member');
}

sub _key_value_parameters {
    my $self = shift;
    # e.g. 'Filter', 'Name','Value',{-filter=>{a=>b}}
    my ($parameter_name,$keyname,$valuename,$args,$skip_undef_values,$append) = @_;  
    my $arg_name     = $self->canonicalize($parameter_name);
    
    my @params;
    if (my $a = $args->{$arg_name}||$args->{"-$parameter_name"}) {
        $parameter_name .= ".$append" if $append;
	my $c = 1;
	if (ref $a && ref $a eq 'HASH') {
	    while (my ($name,$value) = each %$a) {
		push @params,("$parameter_name.$c.$keyname"   => $name);
		if (ref $value && ref $value eq 'ARRAY') {
		    for (my $m=1;$m<=@$value;$m++) {
			push @params,("$parameter_name.$c.$valuename.$m" => $value->[$m-1])
		    }
		} else {
		    push @params,("$parameter_name.$c.$valuename" => $value)
			unless !defined $value && $skip_undef_values;
		}
		$c++;
	    }
	} else {
	    for (ref $a ? @$a : $a) {
		my ($name,$value) = /([^=]+)\s*=\s*(.+)/;
		push @params,("$parameter_name.$c.$keyname"   => $name);
		push @params,("$parameter_name.$c.$valuename" => $value)
		    unless !defined $value && $skip_undef_values;
		$c++;
	    }
	}
    }

    return @params;
}

=head2 @arguments = $ec2->launch_perm_parm($prefix,$suffix,$value)

=cut

sub launch_perm_parm {
    my $self = shift;
    my ($prefix,$suffix,$value) = @_;
    return unless defined $value;
    $self->_perm_parm('LaunchPermission',$prefix,$suffix,$value);
}

sub create_volume_perm_parm {
    my $self = shift;
    my ($prefix,$suffix,$value) = @_;
    return unless defined $value;
    $self->_perm_parm('CreateVolumePermission',$prefix,$suffix,$value);
}

sub _perm_parm {
    my $self = shift;
    my ($base,$prefix,$suffix,$value) = @_;
    return unless defined $value;
    my @list = ref $value && ref $value eq 'ARRAY' ? @$value : $value;
    my $c = 1;
    my @param;
    for my $v (@list) {
	push @param,("$base.$prefix.$c.$suffix" => $v);
	$c++;
    }
    return @param;
}

=head2 @arguments = $ec2->iam_parm($args)

=cut

sub iam_parm {
    my $self = shift;
    my $args = shift;
    my @p;
    push @p,('IamInstanceProfile.Arn'  => $args->{-iam_arn})             if $args->{-iam_arn};
    push @p,('IamInstanceProfile.Name' => $args->{-iam_name})            if $args->{-iam_name};
    return @p;
}

=head2 @arguments = $ec2->block_device_parm($block_device_mapping_string)

=cut

sub block_device_parm {
    my $self    = shift;
    my $devlist = shift or return;

    my @dev     = ref $devlist && ref $devlist eq 'ARRAY' ? @$devlist : $devlist;

    my @p;
    my $c = 1;
    for my $d (@dev) {
	$d =~ /^([^=]+)=([^=]+)$/ or croak "block device mapping must be in format /dev/sdXX=device-name";

	my ($devicename,$blockdevice) = ($1,$2);
	push @p,("BlockDeviceMapping.$c.DeviceName"=>$devicename);

	if ($blockdevice =~ /^vol-/) {  # this is a volume, and not a snapshot
	    my ($volume,$delete_on_term) = split ':',$blockdevice;
	    push @p,("BlockDeviceMapping.$c.Ebs.VolumeId" => $volume);
	    push @p,("BlockDeviceMapping.$c.Ebs.DeleteOnTermination"=>$delete_on_term) 
		if defined $delete_on_term  && $delete_on_term=~/^(true|false|1|0)$/
	}
	elsif ($blockdevice eq 'none') {
	    push @p,("BlockDeviceMapping.$c.NoDevice" => '');
	} elsif ($blockdevice =~ /^ephemeral\d$/) {
	    push @p,("BlockDeviceMapping.$c.VirtualName"=>$blockdevice);
	} else {
	    my ($snapshot,$size,$delete_on_term,$vtype,$iops) = split ':',$blockdevice;

	    # Workaround for apparent bug in 2012-12-01 API; instances will crash without volume size
	    # even if a snapshot ID is provided
	    if ($snapshot) {
		$size ||= eval{$self->describe_snapshots($snapshot)->volumeSize};
		push @p,("BlockDeviceMapping.$c.Ebs.SnapshotId" =>$snapshot);
	    }

	    push @p,("BlockDeviceMapping.$c.Ebs.VolumeSize" =>$size)                    if $size;
	    push @p,("BlockDeviceMapping.$c.Ebs.DeleteOnTermination"=>$delete_on_term) 
		if defined $delete_on_term  && $delete_on_term=~/^(true|false|1|0)$/;
	    push @p,("BlockDeviceMapping.$c.Ebs.VolumeType"=>$vtype)                    if $vtype;
	    push @p,("BlockDeviceMapping.$c.Ebs.Iops"=>$iops)                           if $iops;
	}
	$c++;
    }
    return @p;
}

# ['eth0=eni-123456','eth1=192.168.2.1,192.168.3.1,192.168.4.1:subnet-12345:sg-12345:true:My Weird Network']
# form 1: ethX=network device id
# form 2: ethX=primary_address,secondary_address1,secondary_address2...:subnetId:securityGroupId:deleteOnTermination:description:AssociatePublicIpAddress
# form 3: ethX=primary_address,secondary_address_count:subnetId:securityGroupId:deleteOnTermination:description:AssociatePublicIpAddress
sub network_interface_parm {
    my $self = shift;
    my $args    = shift;
    my $devlist = $args->{-network_interfaces} or return;
    my @dev     = ref $devlist && ref $devlist eq 'ARRAY' ? @$devlist : $devlist;

    my @p;
    my $c = 0;
    for my $d (@dev) {
	$d =~ /^eth(\d+)\s*=\s*([^=]+)$/ or croak "network device mapping must be in format ethX=option-string";

	my ($device_index,$device_options) = ($1,$2);
	push @p,("NetworkInterface.$c.DeviceIndex" => $device_index);
	my @options = split ':',$device_options;
	if (@options == 1) {
	    push @p,("NetworkInterface.$c.NetworkInterfaceId" => $options[0]);
	} 
	else {
	    my ($ip_addresses,$subnet_id,$security_group_id,$delete_on_termination,$description,$assoc_public_ip_addr) = @options;
            # if assoc_public_ip_addr is true, the following conditions must be met:
            #  * can only associate a public address with a single network interface with a device index of 0
            #  * cannot associate a public ip with a second network interface
            #  * cannot assoicate a public ip when launching more than one network interface
            # NOTE: This option defaults to true in a default VPC
            if ($assoc_public_ip_addr) {
                $assoc_public_ip_addr = (($assoc_public_ip_addr eq 'true') && 
                                         ($device_index == 0) && 
                                         (@dev == 1)) ? 'true' : 'false';
            }
	    my @addresses = split /\s*,\s*/,$ip_addresses;
	    for (my $a = 0; $a < @addresses; $a++) {
		if ($addresses[$a] =~ /^\d+\.\d+\.\d+\.\d+$/ ) {
		    push @p,("NetworkInterface.$c.PrivateIpAddresses.$a.PrivateIpAddress" => $addresses[$a]);
		    push @p,("NetworkInterface.$c.PrivateIpAddresses.$a.Primary"          => $a == 0 ? 'true' : 'false');
		}
		elsif ($addresses[$a] =~ /^\d+$/ && $a > 0) {
		    push @p,("NetworkInterface.$c.SecondaryPrivateIpAddressCount"        => $addresses[$a]);
		}
	    }
	    my @sgs = split ',',$security_group_id;
	    for (my $i=0;$i<@sgs;$i++) {
		push @p,("NetworkInterface.$c.SecurityGroupId.$i" => $sgs[$i]);
	    }

	    push @p,("NetworkInterface.$c.SubnetId"              => $subnet_id)             if length $subnet_id;
	    push @p,("NetworkInterface.$c.DeleteOnTermination"   => $delete_on_termination) if length $delete_on_termination;
	    push @p,("NetworkInterface.$c.Description"           => $description)           if length $description;
	    push @p,("NetworkInterface.$c.AssociatePublicIpAddress" => $assoc_public_ip_addr) if $assoc_public_ip_addr;
	}
	$c++;
    }
    return @p;
}

sub boolean_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    my $name = $self->canonicalize($argname);
    return unless exists $args->{$name} || exists $args->{$argname};
    my $val = $args->{$name} || $args->{$argname};
    return ($argname => $val ? 'true' : 'false');
}

sub boolean_value_parm {
    my $self = shift;
    my ($argname,$args) = @_;
    my $name = $self->canonicalize($argname);
    return unless exists $args->{$name} || exists $args->{$argname};
    my $val = $args->{$name} || $args->{$argname};
    return ("$argname.Value" => $val ? 'true' : 'false');
}

=head2 $version = $ec2->version()

Returns the API version to be sent to the endpoint. Calls
guess_version_from_endpoint() to determine this.

=cut

sub version  { 
    my $self = shift;
    return $self->{version} ||=  $self->guess_version_from_endpoint();
}

=head2 $version = $ec2->guess_version_from_endpoint()

This method attempts to guess what version string to use when
communicating with various endpoints. When talking to endpoints that
contain the string "Eucalyptus" uses the old EC2 API
"2009-04-04". When talking to other endpoints, uses the latest EC2
version string.

=cut

sub guess_version_from_endpoint {
    my $self = shift;
    my $endpoint = $self->endpoint;
    return '2009-04-04' if $endpoint =~ /Eucalyptus/;  # eucalyptus version according to http://www.eucalyptus.com/participate/code
    return '2014-05-01';                               # most recent AWS version that we support
}

=head2 $ts = $ec2->timestamp

=cut

sub timestamp {
    return strftime("%Y-%m-%dT%H:%M:%SZ",gmtime);
}


=head2 @obj = $ec2->call($action,@param);

Make a call to Amazon using $action and the passed arguments, and
return a list of objects.

if $VM::EC2::ASYNC is set to true, then will return a
AnyEvent::CondVar object instead of a list of objects. You may
retrieve the objects by calling recv() or setting a callback:

    $VM::EC2::ASYNC = 1;
    my $cv  = $ec2->call('DescribeInstances');
    my @obj = $cv->recv;

or 

    $VM::EC2::ASYNC = 1;
    my $cv  = $ec2->call('DescribeInstances');
    $cv->cb(sub { my @objs = shift->recv;
                  do_something(@objs);
                });

=cut

sub call {
    my $self = shift;
    return $ASYNC ? $self->_call_async(@_) : $self->_call_sync(@_);
}
sub _call_sync {
    my $self = shift;
    my $cv   = $self->_call_async(@_);
    my @obj  = $cv->recv;
    $self->error($cv->error) if $cv->error;
    if (!wantarray) { # scalar context
	return $obj[0] if @obj == 1;
	return         if @obj == 0;
	return @obj;
    } else {
	return @obj;
    }
}

sub _call_async {
    my $self  = shift;
    my ($action,@param) = @_;

    # called if AWS::Signature4 NOT present; use built-in method
    unless (AWS::Signature4->can('new')) {
	my ($action,@param) = @_;
	my $post  = $self->_signature(Action=>$action,@param);
	my $u     = URI->new($self->endpoint);
	$u->query_form(@$post);
	return $self->async_post($action,POST($self->endpoint,Content=>$u->query));
    }


    # called if AWS::Signature4 IS present; use external module
    my $request = POST($self->endpoint,
		       'content-type'=>'application/x-www-form-urlencoded',
		       Content => [
			   Action  => $action,
			   Version => $self->version,
			   @param
		       ]);
    my $access_key = $self->access_key;
    my $secret_key = $self->secret;
    my $host       = URI->new($self->endpoint)->host;
    $request->header('x-amz-security-token'=>$self->security_token) if $self->security_token;
    $request->header('user-agent' => 'VM::EC2-perl');
    $request->header('action'     => $action);  # maybe not necessary, but docs say it is!
    $request->header('host'       => $host);
    
    AWS::Signature4->new(-access_key=>$access_key,
			 -secret_key=>$secret_key)->sign($request);
    $self->async_post($action,$request);
}

sub async_post {
    my $self = shift;
    $self->async_request('POST',@_);
}

sub async_get {
    my $self = shift;
    $self->async_request('GET',@_);
}

sub async_put {
    my $self = shift;
    $self->async_request('PUT',@_);
}

sub async_delete {
    my $self = shift;
    $self->async_request('DELETE',@_);
}

sub async_request {
    my $self = shift;
    my ($method,$action,$request) = @_;

    my @headers;
    $request->headers->scan(sub {push @headers,@_});

    my $cv    = $self->condvar;
    my $callback = sub {
	my $timer = shift;
	http_request(
	    $method => $request->uri,
	    body    => $request->content,
	    headers => {
		TE      => undef,
		Referer => undef,
		@headers,
	    },
	    sub {
		my ($body,$hdr) = @_;
		if ($hdr->{Status} !~ /^2/) { # an error
		    if ($body =~ /RequestLimitExceeded/) {
			warn "RequestLimitExceeded. Retry in ",$timer->next_interval()," seconds\n";
			$timer->retry();
			return;
		    } else {
			$self->async_send_error($action,$hdr,$body,$cv);
			$timer->success();
			return;
		    }
		} else { # success
		    $self->error(undef);
		    my @obj = VM::EC2::Dispatch->content2objects($action,$body,$self);
		    $cv->send(@obj);
		    $timer->success();
		}
	    })
    };
    RetryTimer->new(on_retry       => $callback,
		    interval       => 1,
		    max_retries    => 12,
		    on_max_retries => sub { $cv->error(VM::EC2::Error->new({Code=>500,Message=>'RequestLimitExceeded'},$self)) });

    return $cv;
}

sub async_send_error {
    my $self = shift;
    my ($action,$hdr,$body,$cv) = @_;
    my $error;

    if ($body =~ /<Response>/) {
	$error = VM::EC2::Dispatch->create_error_object($body,$self,$action);
    } elsif ($body =~ /<ErrorResponse xmlns="http:\/\//) {
        $error = VM::EC2::Dispatch->create_alt_error_object($body,$self,$action);
    } else {
	my $code = $hdr->{Status};
        my $msg  = $code =~ /^59[0-9]/ ? $hdr->{Reason} : $body;
	$error = VM::EC2::Error->new({Code=>$code,Message=>"$msg, at API call '$action')"},$self);
    }

    $cv->error($error);

    # this is probably not want we want to do, because it will cause error messages to
    # appear in random places nested into some deep callback.
    carp  "$error"     if $self->print_error;

    if ($self->raise_error) {
	$cv->croak($error);
    } else {
	$cv->send;
    }
}

sub signin_call {
    my $self = shift;
    my ($action,%args) = @_;
    my $endpoint = 'https://signin.aws.amazon.com/federation';

    $args{'Action'} = $action;

    my @param;
    for my $p (sort keys %args) {
	    push @param , join '=' , map { uri_escape($_,"^A-Za-z0-9\-_.~") } ($p,$args{$p});
    }
 
    my $request = GET "$endpoint?" . join '&', @param;

    my $response = $self->ua->request($request);

    return JSON::decode_json($response->content);
}

=head2 $url = $ec2->login_url(-credentials => $credentials, -issuer => $issuer_url, -destination => $console_url);

Returns an HTTP::Request object that points to the URL to login a user with STS credentials

  -credentials => $fed_token->credentials - Credentials from an $ec2->get_federation_token call
  -token => $token                        - a SigninToken from $ec2->get_signin_token call
  -issuer => $issuer_url
  -destination => $console_url            - URL of the AWS console. Defaults to https://console.aws.amazon.com/console/home
  -auto_scaling_group_names     List of auto scaling groups to describe
  -names                        Alias of -auto_scaling_group_names

-credentials or -token are required for this method to work

Usage can be:

  my $fed_token = $ec2->get_federation_token(...);
  my $token = $ec2->get_signin_token(-credentials => $fed_token->credentials);
  my $url = $ec2->login_url(-token => $token->{SigninToken}, -issuer => $issuer_url, -destination => $console_url);

Or:

  my $fed_token = $ec2->get_federation_token(...);
  my $url = $ec2->login_url(-credentials => $fed_token->credentials, -issuer => $issuer_url, -destination => $console_url);

=cut

sub login_url {
    my $self = shift;
    my %args = @_;
    my $endpoint = 'https://signin.aws.amazon.com/federation';

    my %parms; 
    $parms{Action}      = 'login';
    $parms{Destination} = $args{-destination} if ($args{-destination});
    $parms{Issuer}      = $args{-issuer}      if ($args{-issuer});
    $parms{SigninToken} = $args{-token}       if ($args{-token});

    if (defined $args{-credentials} and not defined $parms{SigninToken}) {
        $parms{SigninToken} = $self->get_signin_token(-credentials => $args{-credentials})->{SigninToken};
    }


    my @param;
    for my $p (sort keys %parms) {
	    push @param , join '=' , map { uri_escape($_,"^A-Za-z0-9\-_.~") } ($p,$parms{$p});
    }

    GET "$endpoint?" . join '&', @param;
}

=head2 $request = $ec2->_sign(@args)

Create and sign an HTTP::Request.

=cut

# adapted from Jeff Kim's Net::Amazon::EC2 module
sub _sign {
    my $self = shift;
    my $signature = $self->_signature(@_);
    return POST $self->endpoint,$signature;
}

sub _signature {
    my $self    = shift;
    my @args    = @_;

    my $action = 'POST';
    my $uri    = URI->new($self->endpoint);
    my $host   = $uri->host_port;
    $host      =~ s/:(80|443)$//;  # default ports will break
    my $path   = $uri->path||'/';

    my %sign_hash                = @args;
    $sign_hash{AWSAccessKeyId}   = $self->id;
    $sign_hash{Timestamp}        = $self->timestamp;
    $sign_hash{Version}          = $self->version;
    $sign_hash{SignatureVersion} = 2;
    $sign_hash{SignatureMethod}  = 'HmacSHA256';
    $sign_hash{SecurityToken}    = $self->security_token if $self->security_token;

    my @param;
    my @parameter_keys = sort keys %sign_hash;
    for my $p (@parameter_keys) {
	push @param,join '=',map {uri_escape($_,"^A-Za-z0-9\-_.~")} ($p,$sign_hash{$p});
    }
    my $to_sign = join("\n",
		       $action,$host,$path,join('&',@param));
    my $signature = encode_base64(hmac_sha256($to_sign,$self->secret),'');
    $sign_hash{Signature} = $signature;
    return [%sign_hash];
}

=head2 @param = $ec2->args(ParamName=>@_)

Set up calls that take either method(-resource_id=>'foo') or method('foo').

=cut

sub args {
    my $self = shift;
    my $default_param_name = shift;
    return unless @_;
    return @_ if $_[0] =~ /^-/;
    return (-filter=>shift) if @_==1 && ref $_[0] && ref $_[0] eq 'HASH';
    return ($default_param_name => \@_);
}

sub condvar {
    bless AnyEvent->condvar,'VM::EC2::CondVar';
}

# utility - retry a call with exponential backoff until it succeeds
package RetryTimer;
use AnyEvent;
use Carp 'croak';

# try a subroutine multiple times with exponential backoff
# until it succeeds. Subroutine must call timer's success() method
# if it succeds, retry() otherwise.

# Arguments
# on_retry=>CODEREF,
# on_max_retries=>CODEREF,
# interval => $seconds,    # defaults to 1
# multiplier=>$fraction,   # defaults to 1.5
# max_retries=>$integer,   # defaults to 10
sub new {
    my $class    = shift;
    my @args     = @_;

    my $self;
    $self = bless {
	timer => AE::timer(0,0, sub {
	    delete $self->{timer};
	    $self->{on_retry}->($self) if $self->{on_retry};
	}),
	tries            => 0,
	current_interval => 0,
	@args,
    },ref $class || $class;

    croak "need a on_retry argument" unless $self->{on_retry};
    $self->{interval}     ||= 1;
    $self->{multiplier}   ||= 1.5;
    $self->{max_retries}  = 10 unless defined $self->{max_retries};
    return $self;
}

sub retry {
    my $self = shift;
    return if $self->{timer};
    $self->{current_interval} = $self->next_interval;
    $self->{tries}++; 

    if ($self->{max_retries} && $self->{max_retries} <= $self->{tries}) {
	delete $self->{timer};
	delete $self->{current_interval};
	$self->{on_max_retries}->($self) if $self->{on_max_retries};
	return;
    }
    $self->{timer} = AE::timer ($self->{current_interval},0,
				sub {
				    delete $self->{timer};
				    $self->{on_retry}->($self)
					if $self && $self->{on_retry};
				});
}

sub next_interval {
    my $self = shift;
    if ($self->{current_interval}) {
	return $self->{current_interval} * $self->{multiplier};
    } else {
	return $self->{interval};
    }
}

sub current_interval { shift->{current_interval} };

sub success {
    my $self = shift;
    delete $self->{current_interval};
    delete $self->{timer};
}

package VM::EC2::CondVar;
use base 'AnyEvent::CondVar';

sub error {
    my $self = shift;
    my $d    = $self->{error};
    $self->{error} = shift if @_;
    return $d;
}

sub recv {
    my $self = shift;
    my @obj  = $self->SUPER::recv;
    if (!wantarray) { # scalar context
	return $obj[0] if @obj == 1;
	return         if @obj == 0;
	return @obj;
    } else {
	return @obj;
    }
}

=head1 OTHER INFORMATION

This section contains technical information that may be of interest to developers.

=head2 Signing and authentication protocol

This module uses Amazon AWS signing protocol version 2, as described at
http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?using-query-api.html.
It uses the HmacSHA256 signature method, which is the most secure
method currently available. For additional security, use "https" for
the communications endpoint:

  $ec2 = VM::EC2->new(-endpoint=>'https://ec2.amazonaws.com');

=head2 Subclassing VM::EC2 objects

To subclass VM::EC2 objects (or implement your own from scratch) you
will need to override the object dispatch mechanism. Fortunately this
is very easy. After "use VM::EC2" call
VM::EC2::Dispatch->register() one or more times:

 VM::EC2::Dispatch->register($call_name => $dispatch).

The first argument, $call_name, is name of the Amazon API call, such as "DescribeImages".

The second argument, $dispatch, instructs VM::EC2::Dispatch how to
create objects from the parsed XML. There are three possible syntaxes:

 1) A CODE references, such as an anonymous subroutine.

    In this case the code reference will be invoked to handle the 
    parsed XML returned from the request. The code will receive 
    two arguments consisting of the parsed
    content of the response, and the VM::EC2 object used to generate the
    request.

 2) A VM::EC2::Dispatch method name, optionally followed by its arguments
    delimited by commas. Example:

           "fetch_items,securityGroupInfo,VM::EC2::SecurityGroup"

    This tells Dispatch to invoke its fetch_items() method with
    the following arguments:

     $dispatch->fetch_items($parsed_xml,$ec2,'securityGroupInfo','VM::EC2::SecurityGroup')

    The fetch_items() method is used for responses in which a
    list of objects is embedded within a series of <item> tags.
    See L<VM::EC2::Dispatch> for more information.

    Other commonly-used methods are "fetch_one", and "boolean".

 3) A class name, such as 'MyVolume'

    In this case, class MyVolume is loaded and then its new() method
    is called with the four arguments ($parsed_xml,$ec2,$xmlns,$requestid),
    where $parsed_xml is the parsed XML response, $ec2 is the VM::EC2
    object that generated the request, $xmlns is the XML namespace
    of the XML response, and $requestid is the AWS-generated ID for the
    request. Only the first two arguments are really useful.

    I suggest you inherit from VM::EC2::Generic and use the inherited new()
    method to store the parsed XML object and other arguments.

Dispatch tries each of (1), (2) and (3), in order. This means that
class names cannot collide with method names.

The parsed content is the result of passing the raw XML through a
XML::Simple object created with:

 XML::Simple->new(ForceArray    => ['item'],
                  KeyAttr       => ['key'],
                  SuppressEmpty => undef);

In general, this will give you a hash of hashes. Any tag named 'item'
will be forced to point to an array reference, and any tag named "key"
will be flattened as described in the XML::Simple documentation.

A simple way to examine the raw parsed XML is to invoke any
VM::EC2::Generic's as_string() method:

 my ($i) = $ec2->describe_instances;
 print $i->as_string;

This will give you a Data::Dumper representation of the XML after it
has been parsed.

The suggested way to override the dispatch table is from within a
subclass of VM::EC2:
 
 package 'VM::EC2New';
 use base 'VM::EC2';
  sub new {
      my $self=shift;
      VM::EC2::Dispatch->register('call_name_1'=>\&subroutine1).
      VM::EC2::Dispatch->register('call_name_2'=>\&subroutine2).
      $self->SUPER::new(@_);
 }

See L<VM::EC2::Dispatch> for a working example of subclassing VM::EC2
and one of its object classes.

=head1 DEVELOPING

The git source for this library can be found at https://github.com/lstein/LibVM-EC2-Perl,
To contribute to development, please obtain a github account and then either:
 
 1) Fork a copy of the repository, make your changes against this repository, 
    and send a pull request to me to incorporate your changes.

 2) Contact me by email and ask for push privileges on the repository.

See http://help.github.com/ for help getting started.

=head1 SEE ALSO

L<Net::Amazon::EC2>
L<VM::EC2::Dispatch>
L<VM::EC2::Generic>
L<VM::EC2::BlockDevice>
L<VM::EC2::BlockDevice::Attachment>
L<VM::EC2::BlockDevice::EBS>
L<VM::EC2::BlockDevice::Mapping>
L<VM::EC2::BlockDevice::Mapping::EBS>
L<VM::EC2::Error>
L<VM::EC2::Generic>
L<VM::EC2::Group>
L<VM::EC2::Image>
L<VM::EC2::Instance>
L<VM::EC2::Instance::ConsoleOutput>
L<VM::EC2::Instance::Metadata>
L<VM::EC2::Instance::MonitoringState>
L<VM::EC2::Instance::PasswordData>
L<VM::EC2::Instance::Set>
L<VM::EC2::Instance::State>
L<VM::EC2::Instance::State::Change>
L<VM::EC2::Instance::State::Reason>
L<VM::EC2::KeyPair>
L<VM::EC2::Region>
L<VM::EC2::ReservationSet>
L<VM::EC2::ReservedInstance>
L<VM::EC2::ReservedInstance::Offering>
L<VM::EC2::SecurityGroup>
L<VM::EC2::Snapshot>
L<VM::EC2::Staging::Manager>
L<VM::EC2::Tag>
L<VM::EC2::Volume>

=head1 AUTHOR

Lincoln Stein E<lt>lincoln.stein@gmail.comE<gt>.

Copyright (c) 2011 Ontario Institute for Cancer Research

This package and its accompanying libraries is free software; you can
redistribute it and/or modify it under the terms of the GPL (either
version 1, or at your option, any later version) or the Artistic
License 2.0.  Refer to LICENSE for the full license text. In addition,
please see DISCLAIMER.txt for disclaimers of warranty.

=cut


1;