command/agent/agent.go
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package agent
import (
"fmt"
"log"
"net"
"os"
"os/signal"
"strconv"
"strings"
"syscall"
"time"
"git.j3s.sh/cascade/agent"
)
// gracefulTimeout controls how long we wait before forcefully terminating
// note that this value interacts with serf's LeavePropagateDelay config
const gracefulTimeout = 10 * time.Second
func Run(args []string) {
// do flags
config := configureAgent()
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 configureAgent() *agent.Config {
config := agent.DefaultConfig()
// CASCADE_BIND=192.168.0.15:12345
if os.Getenv("CASCADE_BIND") != "" {
err := parseFlagAddress(os.Getenv("CASCADE_BIND"), config.BindAddr)
if err != nil {
fmt.Printf("Error parsing CASCADE_BIND: %s\n", err)
os.Exit(1)
}
}
// 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
}
// parseFlagAddress takes a colon-delimited host:port pair as a string, parses
// out the ip (and optionally, the port), and modifies the passed TCPAddr with
// the resulting values.
func parseFlagAddress(hostPort string, tcpAddr *net.TCPAddr) error {
addr, portStr, err := net.SplitHostPort(hostPort)
if err != nil {
if !strings.Contains(err.Error(), "missing port in address") {
return fmt.Errorf("Error parsing address: %v", err)
}
// If we get a missing port error, we try to coerce the whole hostPort
// into an address. This allows the user to supply just a host address
// instead of always requiring a host:ip pair.
addr = hostPort
}
if addr == "" {
return fmt.Errorf("Error parsing blank address")
}
ip := net.ParseIP(addr)
if ip == nil {
return fmt.Errorf("Error parsing address %q: not a valid IP address", ip)
}
if portStr != "" {
port, err := strconv.Atoi(portStr)
if err != nil {
return fmt.Errorf("Error parsing port: %s", err)
}
tcpAddr.Port = port
}
tcpAddr.IP = ip
return nil
}