/usr/share/gocode/src/github.com/hashicorp/serf/command/agent/command.go is in golang-github-hashicorp-serf-dev 0.6.4~ds1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"flag"
"fmt"
"github.com/armon/go-metrics"
"github.com/hashicorp/go-syslog"
"github.com/hashicorp/logutils"
"github.com/hashicorp/memberlist"
"github.com/hashicorp/serf/serf"
"github.com/mitchellh/cli"
"io"
"log"
"net"
"os"
"os/signal"
"runtime"
"strings"
"syscall"
"time"
)
const (
// gracefulTimeout controls how long we wait before forcefully terminating
gracefulTimeout = 3 * time.Second
// minRetryInterval applies a lower bound to the join retry interval
minRetryInterval = time.Second
)
// Command is a Command implementation that runs a Serf agent.
// The command will not end unless a shutdown message is sent on the
// ShutdownCh. If two messages are sent on the ShutdownCh it will forcibly
// exit.
type Command struct {
Ui cli.Ui
ShutdownCh <-chan struct{}
args []string
scriptHandler *ScriptEventHandler
logFilter *logutils.LevelFilter
logger *log.Logger
}
// readConfig is responsible for setup of our configuration using
// the command line and any file configs
func (c *Command) readConfig() *Config {
var cmdConfig Config
var configFiles []string
var tags []string
var retryInterval string
cmdFlags := flag.NewFlagSet("agent", flag.ContinueOnError)
cmdFlags.Usage = func() { c.Ui.Output(c.Help()) }
cmdFlags.StringVar(&cmdConfig.BindAddr, "bind", "", "address to bind listeners to")
cmdFlags.StringVar(&cmdConfig.AdvertiseAddr, "advertise", "", "address to advertise to cluster")
cmdFlags.Var((*AppendSliceValue)(&configFiles), "config-file",
"json file to read config from")
cmdFlags.Var((*AppendSliceValue)(&configFiles), "config-dir",
"directory of json files to read")
cmdFlags.StringVar(&cmdConfig.EncryptKey, "encrypt", "", "encryption key")
cmdFlags.StringVar(&cmdConfig.KeyringFile, "keyring-file", "", "path to the keyring file")
cmdFlags.Var((*AppendSliceValue)(&cmdConfig.EventHandlers), "event-handler",
"command to execute when events occur")
cmdFlags.Var((*AppendSliceValue)(&cmdConfig.StartJoin), "join",
"address of agent to join on startup")
cmdFlags.BoolVar(&cmdConfig.ReplayOnJoin, "replay", false,
"replay events for startup join")
cmdFlags.StringVar(&cmdConfig.LogLevel, "log-level", "", "log level")
cmdFlags.StringVar(&cmdConfig.NodeName, "node", "", "node name")
cmdFlags.IntVar(&cmdConfig.Protocol, "protocol", -1, "protocol version")
cmdFlags.StringVar(&cmdConfig.Role, "role", "", "role name")
cmdFlags.StringVar(&cmdConfig.RPCAddr, "rpc-addr", "",
"address to bind RPC listener to")
cmdFlags.StringVar(&cmdConfig.Profile, "profile", "", "timing profile to use (lan, wan, local)")
cmdFlags.StringVar(&cmdConfig.SnapshotPath, "snapshot", "", "path to the snapshot file")
cmdFlags.Var((*AppendSliceValue)(&tags), "tag",
"tag pair, specified as key=value")
cmdFlags.StringVar(&cmdConfig.Discover, "discover", "", "mDNS discovery name")
cmdFlags.StringVar(&cmdConfig.Interface, "iface", "", "interface to bind to")
cmdFlags.StringVar(&cmdConfig.TagsFile, "tags-file", "", "tag persistence file")
cmdFlags.BoolVar(&cmdConfig.EnableSyslog, "syslog", false,
"enable logging to syslog facility")
cmdFlags.Var((*AppendSliceValue)(&cmdConfig.RetryJoin), "retry-join",
"address of agent to join on startup with retry")
cmdFlags.IntVar(&cmdConfig.RetryMaxAttempts, "retry-max", 0, "maximum retry join attempts")
cmdFlags.StringVar(&retryInterval, "retry-interval", "", "retry join interval")
cmdFlags.BoolVar(&cmdConfig.RejoinAfterLeave, "rejoin", false,
"enable re-joining after a previous leave")
if err := cmdFlags.Parse(c.args); err != nil {
return nil
}
// Parse any command line tag values
tagValues, err := UnmarshalTags(tags)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error: %s", err))
return nil
}
cmdConfig.Tags = tagValues
// Decode the interval if given
if retryInterval != "" {
dur, err := time.ParseDuration(retryInterval)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error: %s", err))
return nil
}
cmdConfig.RetryInterval = dur
}
config := DefaultConfig()
if len(configFiles) > 0 {
fileConfig, err := ReadConfigPaths(configFiles)
if err != nil {
c.Ui.Error(err.Error())
return nil
}
config = MergeConfig(config, fileConfig)
}
config = MergeConfig(config, &cmdConfig)
if config.NodeName == "" {
hostname, err := os.Hostname()
if err != nil {
c.Ui.Error(fmt.Sprintf("Error determining hostname: %s", err))
return nil
}
config.NodeName = hostname
}
eventScripts := config.EventScripts()
for _, script := range eventScripts {
if !script.Valid() {
c.Ui.Error(fmt.Sprintf("Invalid event script: %s", script.String()))
return nil
}
}
// Check for a valid interface
if _, err := config.NetworkInterface(); err != nil {
c.Ui.Error(fmt.Sprintf("Invalid network interface: %s", err))
return nil
}
// Backward compatibility hack for 'Role'
if config.Role != "" {
c.Ui.Output("Deprecation warning: 'Role' has been replaced with 'Tags'")
config.Tags["role"] = config.Role
}
// Check for sane retry interval
if config.RetryInterval < minRetryInterval {
c.Ui.Output(fmt.Sprintf("Warning: 'RetryInterval' is too low. Setting to %v", config.RetryInterval))
config.RetryInterval = minRetryInterval
}
// Check snapshot file is provided if we have RejoinAfterLeave
if config.RejoinAfterLeave && config.SnapshotPath == "" {
c.Ui.Output("Warning: 'RejoinAfterLeave' enabled without snapshot file")
}
return config
}
// setupAgent is used to create the agent we use
func (c *Command) setupAgent(config *Config, logOutput io.Writer) *Agent {
bindIP, bindPort, err := config.AddrParts(config.BindAddr)
if err != nil {
c.Ui.Error(fmt.Sprintf("Invalid bind address: %s", err))
return nil
}
// Check if we have an interface
if iface, _ := config.NetworkInterface(); iface != nil {
addrs, err := iface.Addrs()
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to get interface addresses: %s", err))
return nil
}
if len(addrs) == 0 {
c.Ui.Error(fmt.Sprintf("Interface '%s' has no addresses", config.Interface))
return nil
}
// If there is no bind IP, pick an address
if bindIP == "0.0.0.0" {
found := false
for _, a := range addrs {
var addrIP net.IP
if runtime.GOOS == "windows" {
// Waiting for https://github.com/golang/go/issues/5395 to use IPNet only
addr, ok := a.(*net.IPAddr)
if !ok {
continue
}
addrIP = addr.IP
} else {
addr, ok := a.(*net.IPNet)
if !ok {
continue
}
addrIP = addr.IP
}
// Skip self-assigned IPs
if addrIP.IsLinkLocalUnicast() {
continue
}
// Found an IP
found = true
bindIP = addrIP.String()
c.Ui.Output(fmt.Sprintf("Using interface '%s' address '%s'",
config.Interface, bindIP))
// Update the configuration
bindAddr := &net.TCPAddr{
IP: net.ParseIP(bindIP),
Port: bindPort,
}
config.BindAddr = bindAddr.String()
break
}
if !found {
c.Ui.Error(fmt.Sprintf("Failed to find usable address for interface '%s'", config.Interface))
return nil
}
} else {
// If there is a bind IP, ensure it is available
found := false
for _, a := range addrs {
addr, ok := a.(*net.IPNet)
if !ok {
continue
}
if addr.IP.String() == bindIP {
found = true
break
}
}
if !found {
c.Ui.Error(fmt.Sprintf("Interface '%s' has no '%s' address",
config.Interface, bindIP))
return nil
}
}
}
var advertiseIP string
var advertisePort int
if config.AdvertiseAddr != "" {
advertiseIP, advertisePort, err = config.AddrParts(config.AdvertiseAddr)
if err != nil {
c.Ui.Error(fmt.Sprintf("Invalid advertise address: %s", err))
return nil
}
}
encryptKey, err := config.EncryptBytes()
if err != nil {
c.Ui.Error(fmt.Sprintf("Invalid encryption key: %s", err))
return nil
}
serfConfig := serf.DefaultConfig()
switch config.Profile {
case "lan":
serfConfig.MemberlistConfig = memberlist.DefaultLANConfig()
case "wan":
serfConfig.MemberlistConfig = memberlist.DefaultWANConfig()
case "local":
serfConfig.MemberlistConfig = memberlist.DefaultLocalConfig()
default:
c.Ui.Error(fmt.Sprintf("Unknown profile: %s", config.Profile))
return nil
}
serfConfig.MemberlistConfig.BindAddr = bindIP
serfConfig.MemberlistConfig.BindPort = bindPort
serfConfig.MemberlistConfig.AdvertiseAddr = advertiseIP
serfConfig.MemberlistConfig.AdvertisePort = advertisePort
serfConfig.MemberlistConfig.SecretKey = encryptKey
serfConfig.NodeName = config.NodeName
serfConfig.Tags = config.Tags
serfConfig.SnapshotPath = config.SnapshotPath
serfConfig.ProtocolVersion = uint8(config.Protocol)
serfConfig.CoalescePeriod = 3 * time.Second
serfConfig.QuiescentPeriod = time.Second
serfConfig.UserCoalescePeriod = 3 * time.Second
serfConfig.UserQuiescentPeriod = time.Second
if config.ReconnectInterval != 0 {
serfConfig.ReconnectInterval = config.ReconnectInterval
}
if config.ReconnectTimeout != 0 {
serfConfig.ReconnectTimeout = config.ReconnectTimeout
}
if config.TombstoneTimeout != 0 {
serfConfig.TombstoneTimeout = config.TombstoneTimeout
}
serfConfig.EnableNameConflictResolution = !config.DisableNameResolution
if config.KeyringFile != "" {
serfConfig.KeyringFile = config.KeyringFile
}
serfConfig.RejoinAfterLeave = config.RejoinAfterLeave
// Start Serf
c.Ui.Output("Starting Serf agent...")
agent, err := Create(config, serfConfig, logOutput)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to start the Serf agent: %v", err))
return nil
}
return agent
}
// setupLoggers is used to setup the logGate, logWriter, and our logOutput
func (c *Command) setupLoggers(config *Config) (*GatedWriter, *logWriter, io.Writer) {
// Setup logging. First create the gated log writer, which will
// store logs until we're ready to show them. Then create the level
// filter, filtering logs of the specified level.
logGate := &GatedWriter{
Writer: &cli.UiWriter{Ui: c.Ui},
}
c.logFilter = LevelFilter()
c.logFilter.MinLevel = logutils.LogLevel(strings.ToUpper(config.LogLevel))
c.logFilter.Writer = logGate
if !ValidateLevelFilter(c.logFilter.MinLevel, c.logFilter) {
c.Ui.Error(fmt.Sprintf(
"Invalid log level: %s. Valid log levels are: %v",
c.logFilter.MinLevel, c.logFilter.Levels))
return nil, nil, nil
}
// Check if syslog is enabled
var syslog io.Writer
if config.EnableSyslog {
l, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, config.SyslogFacility, "serf")
if err != nil {
c.Ui.Error(fmt.Sprintf("Syslog setup failed: %v", err))
return nil, nil, nil
}
syslog = &SyslogWrapper{l}
}
// Create a log writer, and wrap a logOutput around it
logWriter := NewLogWriter(512)
var logOutput io.Writer
if syslog != nil {
logOutput = io.MultiWriter(c.logFilter, logWriter, syslog)
} else {
logOutput = io.MultiWriter(c.logFilter, logWriter)
}
// Create a logger
c.logger = log.New(logOutput, "", log.LstdFlags)
return logGate, logWriter, logOutput
}
// startAgent is used to start the agent and IPC
func (c *Command) startAgent(config *Config, agent *Agent,
logWriter *logWriter, logOutput io.Writer) *AgentIPC {
// Add the script event handlers
c.scriptHandler = &ScriptEventHandler{
SelfFunc: func() serf.Member { return agent.Serf().LocalMember() },
Scripts: config.EventScripts(),
Logger: log.New(logOutput, "", log.LstdFlags),
}
agent.RegisterEventHandler(c.scriptHandler)
// Start the agent after the handler is registered
if err := agent.Start(); err != nil {
c.Ui.Error(fmt.Sprintf("Failed to start the Serf agent: %v", err))
return nil
}
// Parse the bind address information
bindIP, bindPort, err := config.AddrParts(config.BindAddr)
bindAddr := &net.TCPAddr{IP: net.ParseIP(bindIP), Port: bindPort}
// Start the discovery layer
if config.Discover != "" {
// Use the advertise addr and port
local := agent.Serf().Memberlist().LocalNode()
// Get the bind interface if any
iface, _ := config.NetworkInterface()
_, err := NewAgentMDNS(agent, logOutput, config.ReplayOnJoin,
config.NodeName, config.Discover, iface, local.Addr, int(local.Port))
if err != nil {
c.Ui.Error(fmt.Sprintf("Error starting mDNS listener: %s", err))
return nil
}
}
// Setup the RPC listener
rpcListener, err := net.Listen("tcp", config.RPCAddr)
if err != nil {
c.Ui.Error(fmt.Sprintf("Error starting RPC listener: %s", err))
return nil
}
// Start the IPC layer
c.Ui.Output("Starting Serf agent RPC...")
ipc := NewAgentIPC(agent, config.RPCAuthKey, rpcListener, logOutput, logWriter)
c.Ui.Output("Serf agent running!")
c.Ui.Info(fmt.Sprintf(" Node name: '%s'", config.NodeName))
c.Ui.Info(fmt.Sprintf(" Bind addr: '%s'", bindAddr.String()))
if config.AdvertiseAddr != "" {
advertiseIP, advertisePort, _ := config.AddrParts(config.AdvertiseAddr)
advertiseAddr := (&net.TCPAddr{IP: net.ParseIP(advertiseIP), Port: advertisePort}).String()
c.Ui.Info(fmt.Sprintf("Advertise addr: '%s'", advertiseAddr))
}
c.Ui.Info(fmt.Sprintf(" RPC addr: '%s'", config.RPCAddr))
c.Ui.Info(fmt.Sprintf(" Encrypted: %#v", agent.serf.EncryptionEnabled()))
c.Ui.Info(fmt.Sprintf(" Snapshot: %v", config.SnapshotPath != ""))
c.Ui.Info(fmt.Sprintf(" Profile: %s", config.Profile))
if config.Discover != "" {
c.Ui.Info(fmt.Sprintf(" mDNS cluster: %s", config.Discover))
}
return ipc
}
// startupJoin is invoked to handle any joins specified to take place at start time
func (c *Command) startupJoin(config *Config, agent *Agent) error {
if len(config.StartJoin) == 0 {
return nil
}
c.Ui.Output(fmt.Sprintf("Joining cluster...(replay: %v)", config.ReplayOnJoin))
n, err := agent.Join(config.StartJoin, config.ReplayOnJoin)
if err != nil {
return err
}
c.Ui.Info(fmt.Sprintf("Join completed. Synced with %d initial agents", n))
return nil
}
// retryJoin is invoked to handle joins with retries. This runs until at least a
// single successful join or RetryMaxAttempts is reached
func (c *Command) retryJoin(config *Config, agent *Agent, errCh chan struct{}) {
// Quit fast if there is no nodes to join
if len(config.RetryJoin) == 0 {
return
}
// Track the number of join attempts
attempt := 0
for {
// Try to perform the join
c.logger.Printf("[INFO] agent: Joining cluster...(replay: %v)", config.ReplayOnJoin)
n, err := agent.Join(config.RetryJoin, config.ReplayOnJoin)
if err == nil {
c.logger.Printf("[INFO] agent: Join completed. Synced with %d initial agents", n)
return
}
// Check if the maximum attempts has been exceeded
attempt++
if config.RetryMaxAttempts > 0 && attempt > config.RetryMaxAttempts {
c.logger.Printf("[ERR] agent: maximum retry join attempts made, exiting")
close(errCh)
return
}
// Log the failure and sleep
c.logger.Printf("[WARN] agent: Join failed: %v, retrying in %v", err, config.RetryInterval)
time.Sleep(config.RetryInterval)
}
}
func (c *Command) Run(args []string) int {
c.Ui = &cli.PrefixedUi{
OutputPrefix: "==> ",
InfoPrefix: " ",
ErrorPrefix: "==> ",
Ui: c.Ui,
}
// Parse our configs
c.args = args
config := c.readConfig()
if config == nil {
return 1
}
// Setup the log outputs
logGate, logWriter, logOutput := c.setupLoggers(config)
if logWriter == nil {
return 1
}
/*
Setup telemetry
Aggregate on 10 second intervals for 1 minute. Expose the
metrics over stderr when there is a SIGUSR1 received.
*/
inm := metrics.NewInmemSink(10*time.Second, time.Minute)
metrics.DefaultInmemSignal(inm)
metricsConf := metrics.DefaultConfig("serf-agent")
if config.StatsiteAddr != "" {
sink, err := metrics.NewStatsiteSink(config.StatsiteAddr)
if err != nil {
c.Ui.Error(fmt.Sprintf("Failed to start statsite sink. Got: %s", err))
return 1
}
fanout := metrics.FanoutSink{inm, sink}
metrics.NewGlobal(metricsConf, fanout)
} else {
metricsConf.EnableHostname = false
metrics.NewGlobal(metricsConf, inm)
}
// Setup serf
agent := c.setupAgent(config, logOutput)
if agent == nil {
return 1
}
defer agent.Shutdown()
// Start the agent
ipc := c.startAgent(config, agent, logWriter, logOutput)
if ipc == nil {
return 1
}
defer ipc.Shutdown()
// Join startup nodes if specified
if err := c.startupJoin(config, agent); err != nil {
c.Ui.Error(err.Error())
return 1
}
// Enable log streaming
c.Ui.Info("")
c.Ui.Output("Log data will now stream in as it occurs:\n")
logGate.Flush()
// Start the retry joins
retryJoinCh := make(chan struct{})
go c.retryJoin(config, agent, retryJoinCh)
// Wait for exit
return c.handleSignals(config, agent, retryJoinCh)
}
// handleSignals blocks until we get an exit-causing signal
func (c *Command) handleSignals(config *Config, agent *Agent, retryJoin chan struct{}) int {
signalCh := make(chan os.Signal, 4)
signal.Notify(signalCh, os.Interrupt, syscall.SIGTERM, syscall.SIGHUP)
// Wait for a signal
WAIT:
var sig os.Signal
select {
case s := <-signalCh:
sig = s
case <-c.ShutdownCh:
sig = os.Interrupt
case <-retryJoin:
// Retry join failed!
return 1
case <-agent.ShutdownCh():
// Agent is already shutdown!
return 0
}
c.Ui.Output(fmt.Sprintf("Caught signal: %v", sig))
// Check if this is a SIGHUP
if sig == syscall.SIGHUP {
config = c.handleReload(config, agent)
goto WAIT
}
// Check if we should do a graceful leave
graceful := false
if sig == os.Interrupt && !config.SkipLeaveOnInt {
graceful = true
} else if sig == syscall.SIGTERM && config.LeaveOnTerm {
graceful = true
}
// Bail fast if not doing a graceful leave
if !graceful {
return 1
}
// Attempt a graceful leave
gracefulCh := make(chan struct{})
c.Ui.Output("Gracefully shutting down agent...")
go func() {
if err := agent.Leave(); err != nil {
c.Ui.Error(fmt.Sprintf("Error: %s", err))
return
}
close(gracefulCh)
}()
// Wait for leave or another signal
select {
case <-signalCh:
return 1
case <-time.After(gracefulTimeout):
return 1
case <-gracefulCh:
return 0
}
}
// handleReload is invoked when we should reload our configs, e.g. SIGHUP
func (c *Command) handleReload(config *Config, agent *Agent) *Config {
c.Ui.Output("Reloading configuration...")
newConf := c.readConfig()
if newConf == nil {
c.Ui.Error(fmt.Sprintf("Failed to reload configs"))
return config
}
// Change the log level
minLevel := logutils.LogLevel(strings.ToUpper(newConf.LogLevel))
if ValidateLevelFilter(minLevel, c.logFilter) {
c.logFilter.SetMinLevel(minLevel)
} else {
c.Ui.Error(fmt.Sprintf(
"Invalid log level: %s. Valid log levels are: %v",
minLevel, c.logFilter.Levels))
// Keep the current log level
newConf.LogLevel = config.LogLevel
}
// Change the event handlers
c.scriptHandler.UpdateScripts(newConf.EventScripts())
// Update the tags in serf
if err := agent.SetTags(newConf.Tags); err != nil {
c.Ui.Error(fmt.Sprintf("Failed to update tags: %v", err))
return newConf
}
return newConf
}
func (c *Command) Synopsis() string {
return "Runs a Serf agent"
}
func (c *Command) Help() string {
helpText := `
Usage: serf agent [options]
Starts the Serf agent and runs until an interrupt is received. The
agent represents a single node in a cluster.
Options:
-bind=0.0.0.0 Address to bind network listeners to
-iface Network interface to bind to. Can be used instead of
-bind if the interface is known but not the address.
If both are provided, then Serf verifies that the
interface has the bind address that is provided. This
flag also sets the multicast device used for -discover.
-advertise=0.0.0.0 Address to advertise to the other cluster members
-config-file=foo Path to a JSON file to read configuration from.
This can be specified multiple times.
-config-dir=foo Path to a directory to read configuration files
from. This will read every file ending in ".json"
as configuration in this directory in alphabetical
order.
-discover=cluster Discover is set to enable mDNS discovery of peer. On
networks that support multicast, this can be used to have
peers join each other without an explicit join.
-encrypt=foo Key for encrypting network traffic within Serf.
Must be a base64-encoded 16-byte key.
-keyring-file The keyring file is used to store encryption keys used
by Serf. As encryption keys are changed, the content of
this file is updated so that the same keys may be used
during later agent starts.
-event-handler=foo Script to execute when events occur. This can
be specified multiple times. See the event scripts
section below for more info.
-join=addr An initial agent to join with. This flag can be
specified multiple times.
-log-level=info Log level of the agent.
-node=hostname Name of this node. Must be unique in the cluster
-profile=[lan|wan|local] Profile is used to control the timing profiles used in Serf.
The default if not provided is lan.
-protocol=n Serf protocol version to use. This defaults to
the latest version, but can be set back for upgrades.
-rejoin Ignores a previous leave and attempts to rejoin the cluster.
Only works if provided along with a snapshot file.
-retry-join=addr An agent to join with. This flag be specified multiple times.
Does not exit on failure like -join, used to retry until success.
-retry-interval=30s Sets the interval on which a node will attempt to retry joining
nodes provided by -retry-join. Defaults to 30s.
-retry-max=0 Limits the number of retry events. Defaults to 0 for unlimited.
-role=foo The role of this node, if any. This can be used
by event scripts to differentiate different types
of nodes that may be part of the same cluster.
'-role' is deprecated in favor of '-tag role=foo'.
-rpc-addr=127.0.0.1:7373 Address to bind the RPC listener.
-snapshot=path/to/file The snapshot file is used to store alive nodes and
event information so that Serf can rejoin a cluster
and avoid event replay on restart.
-tag key=value Tag can be specified multiple times to attach multiple
key/value tag pairs to the given node.
-tags-file=/path/to/file The tags file is used to persist tag data. As an agent's
tags are changed, the tags file will be updated. Tags
can be reloaded during later agent starts. This option
is incompatible with the '-tag' option and requires there
be no tags in the agent configuration file, if given.
-syslog When provided, logs will also be sent to syslog.
Event handlers:
For more information on what event handlers are, please read the
Serf documentation. This section will document how to configure them
on the command-line. There are three methods of specifying an event
handler:
- The value can be a plain script, such as "event.sh". In this case,
Serf will send all events to this script, and you'll be responsible
for differentiating between them based on the SERF_EVENT.
- The value can be in the format of "TYPE=SCRIPT", such as
"member-join=join.sh". With this format, Serf will only send events
of that type to that script.
- The value can be in the format of "user:EVENT=SCRIPT", such as
"user:deploy=deploy.sh". This means that Serf will only invoke this
script in the case of user events named "deploy".
`
return strings.TrimSpace(helpText)
}
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