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 }