systemd: add notify support

That way, we can reliably know when the daemon is ready.

Author: Stebalien

cmd/ipfs/daemon.go

@@ -411,10 +411,12 @@ func daemonFunc(req *cmds.Request, re cmds.ResponseEmitter, env cmds.Environment
 
 	// The daemon is *finally* ready.
 	fmt.Printf("Daemon is ready\n")
+	notifyReady()
 
 	// Give the user some immediate feedback when they hit C-c
 	go func() {
 		<-req.Context.Done()
+		notifyStopping()
 		fmt.Println("Received interrupt signal, shutting down...")
 		fmt.Println("(Hit ctrl-c again to force-shutdown the daemon.)")
 	}()

cmd/ipfs/daemon_linux.go

@@ -0,0 +1,15 @@
+// +build linux
+
+package main
+
+import (
+	daemon "github.com/coreos/go-systemd/daemon"
+)
+
+func notifyReady() {
+	_, _ = daemon.SdNotify(false, daemon.SdNotifyReady)
+}
+
+func notifyStopping() {
+	_, _ = daemon.SdNotify(false, daemon.SdNotifyStopping)
+}

cmd/ipfs/daemon_other.go

@@ -0,0 +1,7 @@
+// +build !linux
+
+package main
+
+func notifyReady() {}
+
+func notifyStopping() {}

misc/systemd/ipfs.service

@@ -2,6 +2,7 @@
 Description=IPFS Daemon
 
 [Service]
+Type=notify
 ExecStart=/usr/bin/ipfs daemon --init --migrate
 KillSignal=SIGINT