main.go
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package main
import (
"fmt"
"log"
"os"
"os/signal"
"strings"
"syscall"
"time"
"git.j3s.sh/cascade/agent"
"git.j3s.sh/cascade/ipaddr"
"git.j3s.sh/cascade/list"
)
const usage = `cascade agent start a cascade agent
cascade list|ls list nodes or services
cascade members show serf cluster members
cascade rtt estimate latency between nodes
`
// gracefulTimeout controls how long we wait before forcefully terminating
// note that this value interacts with serf's LeavePropagateDelay config
const gracefulTimeout = 10 * time.Second
// TODO: rename agent to something cooler
func main() {
if len(os.Args) == 1 {
fmt.Fprintf(os.Stderr, "%s", usage)
os.Exit(1)
}
run(os.Args[1], os.Args[2:])
}
func run(command string, args []string) {
switch command {
case "agent":
handleAgent()
case "list", "ls":
list.Run(args)
default:
fmt.Fprintf(os.Stderr, "'%s' is not a valid command\n\n%s", command, usage)
os.Exit(1)
}
}
func handleAgent() {
config := getAgentConfig()
fmt.Printf("%+v", config)
agent := agent.New(config)
if err := agent.Start(); err != nil {
fmt.Println(err)
os.Exit(1)
}
defer agent.Shutdown()
// join any specified startup nodes
if err := startupJoin(agent); err != nil {
fmt.Println(err)
os.Exit(1)
}
if err := handleSignals(agent); err != nil {
fmt.Println(err)
os.Exit(1)
}
}
// handleSignals blocks until we get an exit-causing signal
func handleSignals(agent *agent.Agent) error {
signalCh := make(chan os.Signal, 4)
signal.Notify(signalCh, os.Interrupt, syscall.SIGTERM)
// Wait for a signal
var sig os.Signal
select {
case s := <-signalCh:
sig = s
case <-agent.ShutdownCh():
// Agent is already shutdown!
return nil
}
fmt.Fprintf(os.Stderr, "caught signal %s", sig)
// Check if we should do a graceful leave
graceful := false
if sig == os.Interrupt || sig == syscall.SIGTERM {
graceful = true
}
// Bail fast if not doing a graceful leave
if !graceful {
fmt.Fprintf(os.Stderr, "leave cluster with zero grace")
return nil
}
// Attempt a graceful leave
gracefulCh := make(chan struct{})
fmt.Printf("shutting down gracefully")
go func() {
if err := agent.Leave(); err != nil {
fmt.Println("Error: ", err)
return
}
close(gracefulCh)
}()
// Wait for leave or another signal
select {
case <-signalCh:
return fmt.Errorf("idfk")
case <-time.After(gracefulTimeout):
return fmt.Errorf("leave timed out")
case <-gracefulCh:
return nil
}
}
func startupJoin(a *agent.Agent) error {
if len(a.Config.StartJoin) == 0 {
return nil
}
n, err := a.Join(a.Config.StartJoin)
if err != nil {
return err
}
if n > 0 {
log.Printf("issue join request nodes=%d\n", n)
}
return nil
}
func getAgentConfig() *agent.Config {
config := agent.DefaultConfig()
// CASCADE_BIND=192.168.0.15:12345
if os.Getenv("CASCADE_BIND") != "" {
addr := ipaddr.ParseIPPort(os.Getenv("CASCADE_BIND"))
config.BindAddr.IP = addr.IP
if addr.Port != 0 {
config.BindAddr.Port = addr.Port
}
}
// CASCADE_JOIN=127.0.0.1,127.0.0.5
if os.Getenv("CASCADE_JOIN") != "" {
config.StartJoin = strings.Split(os.Getenv("CASCADE_JOIN"), ",")
}
// CASCADE_NAME=nostromo.j3s.sh
if os.Getenv("CASCADE_NAME") != "" {
config.NodeName = os.Getenv("CASCADE_NAME")
}
return config
}