add support for systemd notify

cmd/root.go

@@ -7,10 +7,12 @@ import (
 	log2 "log"
 	"net/http"
 	"os"
+	"os/signal"
 	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/NYTimes/logrotate"
@@ -26,6 +28,7 @@ import (
 
 	"github.com/pterodactyl/wings/config"
 	"github.com/pterodactyl/wings/environment"
+	"github.com/pterodactyl/wings/internal/notify"
 	"github.com/pterodactyl/wings/loggers/cli"
 	"github.com/pterodactyl/wings/remote"
 	"github.com/pterodactyl/wings/router"
@@ -308,6 +311,7 @@ func rootCmdRun(cmd *cobra.Command, _ []string) {
 	}
 
 	// Check if the server should run with TLS but using autocert.
+	go func(s *http.Server, api config.ApiConfiguration, sys config.SystemConfiguration, autotls bool, tlshostname string) {
 		if autotls {
 			m := autocert.Manager{
 				Prompt:     autocert.AcceptTOS,
@@ -346,6 +350,19 @@ func rootCmdRun(cmd *cobra.Command, _ []string) {
 		if err := s.ListenAndServe(); err != nil {
 			log.WithField("error", err).Fatal("failed to configure HTTP server")
 		}
+	}(s, api, sys, autotls, tlshostname)
+
+	if err := notify.Readiness(); err != nil {
+		log.WithField("error", err).Error("failed to notify systemd of readiness state")
+	}
+
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
+	<-c
+
+	if err := notify.Stopping(); err != nil {
+		log.WithField("error", err).Error("failed to notify systemd of stopping state")
+	}
 }
 
 // Reads the configuration from the disk and then sets up the global singleton

internal/notify/notify.go

@@ -0,0 +1,19 @@
+// Package notify handles notifying the operating system of the program's state.
+//
+// For linux based operating systems, this is done through the systemd socket
+// set by "NOTIFY_SOCKET" environment variable.
+//
+// Currently, no other operating systems are supported.
+package notify
+
+func Readiness() error {
+	return readiness()
+}
+
+func Reloading() error {
+	return reloading()
+}
+
+func Stopping() error {
+	return stopping()
+}

internal/notify/notify_linux.go

@@ -0,0 +1,48 @@
+package notify
+
+import (
+	"io"
+	"net"
+	"os"
+	"strings"
+)
+
+func notify(path string, r io.Reader) error {
+	s := &net.UnixAddr{
+		Name: path,
+		Net:  "unixgram",
+	}
+	c, err := net.DialUnix(s.Net, nil, s)
+	if err != nil {
+		return err
+	}
+	defer c.Close()
+
+	if _, err := io.Copy(c, r); err != nil {
+		return err
+	}
+	return nil
+}
+
+func socketNotify(payload string) error {
+	v, ok := os.LookupEnv("NOTIFY_SOCKET")
+	if !ok || v == "" {
+		return nil
+	}
+	if err := notify(v, strings.NewReader(payload)); err != nil {
+		return err
+	}
+	return nil
+}
+
+func readiness() error {
+	return socketNotify("READY=1")
+}
+
+func reloading() error {
+	return socketNotify("RELOADING=1")
+}
+
+func stopping() error {
+	return socketNotify("STOPPING=1")
+}

internal/notify/notify_other.go

@@ -0,0 +1,15 @@
+// +build !linux
+
+package notify
+
+func readiness() error {
+	return nil
+}
+
+func reloading() error {
+	return nil
+}
+
+func stopping() error {
+	return nil
+}