Add support for sd_notify

Signed-off-by: Dan Walsh <dwalsh@redhat.com>

cmd/server/daemon_linux.go

@@ -0,0 +1,20 @@
+// +build linux
+
+package main
+
+import (
+	"github.com/Sirupsen/logrus"
+	systemdDaemon "github.com/coreos/go-systemd/daemon"
+)
+
+func sdNotify() {
+	if err := systemdDaemon.SdNotify("READY=1"); err != nil {
+		logrus.Warnf("Failed to sd_notify systemd: %v", err)
+	}
+}
+
+// notifySystem sends a message to the host when the server is ready to be used
+func notifySystem() {
+	// Tell the init daemon we are accepting requests
+	go sdNotify()
+}

cmd/server/main.go

@@ -188,6 +188,10 @@ func main() {
 
 		runtime.RegisterRuntimeServiceServer(s, service)
 		runtime.RegisterImageServiceServer(s, service)
+
+		// after the daemon is done setting up we can notify systemd api
+		notifySystem()
+
 		if err := s.Serve(lis); err != nil {
 			logrus.Fatal(err)
 		}

hack/vendor.sh

@@ -46,6 +46,7 @@ case $# in
 	;;
 esac
 
+clone git github.com/coreos/go-systemd/daemon
 clone git github.com/BurntSushi/toml v0.2.0
 clone git github.com/Sirupsen/logrus v0.10.0
 clone git github.com/containers/image f6f11ab5cf8b1e70ef4aa3f8b6fdb4b671d16abd

vendor/src/github.com/coreos/go-systemd/daemon/sdnotify.go

@@ -0,0 +1,31 @@
+// Code forked from Docker project
+package daemon
+
+import (
+	"errors"
+	"net"
+	"os"
+)
+
+var SdNotifyNoSocket = errors.New("No socket")
+
+// SdNotify sends a message to the init daemon. It is common to ignore the error.
+func SdNotify(state string) error {
+	socketAddr := &net.UnixAddr{
+		Name: os.Getenv("NOTIFY_SOCKET"),
+		Net:  "unixgram",
+	}
+
+	if socketAddr.Name == "" {
+		return SdNotifyNoSocket
+	}
+
+	conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	_, err = conn.Write([]byte(state))
+	return err
+}