Server: Support custom TCP listener (#27066)

* Server: Support custom TCP listener

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/api/http_server.go

@@ -71,6 +71,7 @@ type HTTPServer struct {
 	PluginManager        *plugins.PluginManager           `inject:""`
 	SearchService        *search.SearchService            `inject:""`
 	Live                 *live.GrafanaLive
+	Listener             net.Listener
 }
 
 func (hs *HTTPServer) Init() error {
@@ -119,28 +120,9 @@ func (hs *HTTPServer) Run(ctx context.Context) error {
 		}
 	}
 
-	var listener net.Listener
-	switch setting.Protocol {
-	case setting.HTTP, setting.HTTPS, setting.HTTP2:
-		var err error
-		listener, err = net.Listen("tcp", hs.httpSrv.Addr)
-		if err != nil {
-			return errutil.Wrapf(err, "failed to open listener on address %s", hs.httpSrv.Addr)
-		}
-	case setting.SOCKET:
-		var err error
-		listener, err = net.ListenUnix("unix", &net.UnixAddr{Name: setting.SocketPath, Net: "unix"})
-		if err != nil {
-			return errutil.Wrapf(err, "failed to open listener for socket %s", setting.SocketPath)
-		}
-
-		// Make socket writable by group
-		if err := os.Chmod(setting.SocketPath, 0660); err != nil {
-			return errutil.Wrapf(err, "failed to change socket permissions")
-		}
-	default:
-		hs.log.Error("Invalid protocol", "protocol", setting.Protocol)
-		return fmt.Errorf("invalid protocol %q", setting.Protocol)
+	listener, err := hs.getListener()
+	if err != nil {
+		return err
 	}
 
 	hs.log.Info("HTTP Server Listen", "address", listener.Addr().String(), "protocol",
@@ -185,6 +167,36 @@ func (hs *HTTPServer) Run(ctx context.Context) error {
 	return nil
 }
 
+func (hs *HTTPServer) getListener() (net.Listener, error) {
+	if hs.Listener != nil {
+		return hs.Listener, nil
+	}
+
+	switch setting.Protocol {
+	case setting.HTTP, setting.HTTPS, setting.HTTP2:
+		listener, err := net.Listen("tcp", hs.httpSrv.Addr)
+		if err != nil {
+			return nil, errutil.Wrapf(err, "failed to open listener on address %s", hs.httpSrv.Addr)
+		}
+		return listener, nil
+	case setting.SOCKET:
+		listener, err := net.ListenUnix("unix", &net.UnixAddr{Name: setting.SocketPath, Net: "unix"})
+		if err != nil {
+			return nil, errutil.Wrapf(err, "failed to open listener for socket %s", setting.SocketPath)
+		}
+
+		// Make socket writable by group
+		if err := os.Chmod(setting.SocketPath, 0660); err != nil {
+			return nil, errutil.Wrapf(err, "failed to change socket permissions")
+		}
+
+		return listener, nil
+	default:
+		hs.log.Error("Invalid protocol", "protocol", setting.Protocol)
+		return nil, fmt.Errorf("invalid protocol %q", setting.Protocol)
+	}
+}
+
 func (hs *HTTPServer) configureHttps() error {
 	if setting.CertFile == "" {
 		return fmt.Errorf("cert_file cannot be empty when using HTTPS")

pkg/cmd/grafana-server/main.go

@@ -16,6 +16,7 @@ import (
 	"github.com/grafana/grafana/pkg/extensions"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/infra/metrics"
+	"github.com/grafana/grafana/pkg/server"
 	_ "github.com/grafana/grafana/pkg/services/alerting/conditions"
 	_ "github.com/grafana/grafana/pkg/services/alerting/notifiers"
 	"github.com/grafana/grafana/pkg/setting"
@@ -110,14 +111,21 @@ func main() {
 
 	metrics.SetBuildInformation(version, commit, buildBranch)
 
-	server := NewServer(*configFile, *homePath, *pidFile)
+	s, err := server.New(server.Config{
+		ConfigFile: *configFile, HomePath: *homePath, PidFile: *pidFile,
+		Version: version, Commit: commit, BuildBranch: buildBranch,
+	})
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
+		os.Exit(1)
+	}
 
-	go listenToSystemSignals(server)
+	go listenToSystemSignals(s)
 
-	err := server.Run()
+	err = s.Run()
 	code := 0
 	if err != nil {
-		code = server.ExitCode(err)
+		code = s.ExitCode(err)
 	}
 	trace.Stop()
 	log.Close()
@@ -135,7 +143,7 @@ func validPackaging(packaging string) string {
 	return "unknown"
 }
 
-func listenToSystemSignals(server *Server) {
+func listenToSystemSignals(s *server.Server) {
 	signalChan := make(chan os.Signal, 1)
 	sighupChan := make(chan os.Signal, 1)
 
@@ -147,7 +155,7 @@ func listenToSystemSignals(server *Server) {
 		case <-sighupChan:
 			log.Reload()
 		case sig := <-signalChan:
-			server.Shutdown(fmt.Sprintf("System signal: %s", sig))
+			s.Shutdown(fmt.Sprintf("System signal: %s", sig))
 		}
 	}
 }

pkg/server/server.go

@@ -1,4 +1,4 @@
-package main
+package server
 
 import (
 	"context"
@@ -10,6 +10,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/facebookgo/inject"
@@ -43,22 +44,43 @@ import (
 	"github.com/grafana/grafana/pkg/util/errutil"
 )
 
-// NewServer returns a new instance of Server.
-func NewServer(configFile, homePath, pidFile string) *Server {
+// Config contains parameters for the New function.
+type Config struct {
+	ConfigFile  string
+	HomePath    string
+	PidFile     string
+	Version     string
+	Commit      string
+	BuildBranch string
+	Listener    net.Listener
+}
+
+// New returns a new instance of Server.
+func New(cfg Config) (*Server, error) {
 	rootCtx, shutdownFn := context.WithCancel(context.Background())
 	childRoutines, childCtx := errgroup.WithContext(rootCtx)
 
-	return &Server{
+	s := &Server{
 		context:       childCtx,
 		shutdownFn:    shutdownFn,
 		childRoutines: childRoutines,
 		log:           log.New("server"),
 		cfg:           setting.NewCfg(),
 
-		configFile: configFile,
-		homePath:   homePath,
-		pidFile:    pidFile,
+		configFile:  cfg.ConfigFile,
+		homePath:    cfg.HomePath,
+		pidFile:     cfg.PidFile,
+		version:     cfg.Version,
+		commit:      cfg.Commit,
+		buildBranch: cfg.BuildBranch,
+	}
+	if cfg.Listener != nil {
+		if err := s.init(&cfg); err != nil {
+			return nil, err
+		}
 	}
+
+	return s, nil
 }
 
 // Server is responsible for managing the lifecycle of services.
@@ -70,18 +92,29 @@ type Server struct {
 	cfg                *setting.Cfg
 	shutdownReason     string
 	shutdownInProgress bool
+	isInitialized      bool
+	mtx                sync.Mutex
 
-	configFile string
-	homePath   string
-	pidFile    string
+	configFile  string
+	homePath    string
+	pidFile     string
+	version     string
+	commit      string
+	buildBranch string
 
-	RouteRegister routing.RouteRegister `inject:""`
-	HTTPServer    *api.HTTPServer       `inject:""`
+	HTTPServer *api.HTTPServer `inject:""`
 }
 
-// Run initializes and starts services. This will block until all services have
-// exited. To initiate shutdown, call the Shutdown method in another goroutine.
-func (s *Server) Run() (err error) {
+// init initializes the server and its services.
+func (s *Server) init(cfg *Config) error {
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
+
+	if s.isInitialized {
+		return nil
+	}
+	s.isInitialized = true
+
 	s.loadConfiguration()
 	s.writePIDFile()
 
@@ -89,9 +122,8 @@ func (s *Server) Run() (err error) {
 	social.NewOAuthService()
 
 	services := registry.GetServices()
-
-	if err = s.buildServiceGraph(services); err != nil {
-		return
+	if err := s.buildServiceGraph(services); err != nil {
+		return err
 	}
 
 	// Initialize services.
@@ -100,13 +132,33 @@ func (s *Server) Run() (err error) {
 			continue
 		}
 
-		s.log.Debug("Initializing " + service.Name)
-
+		if cfg != nil {
+			if httpS, ok := service.Instance.(*api.HTTPServer); ok {
+				// Configure the api.HTTPServer if necessary
+				// Hopefully we can find a better solution, maybe with a more advanced DI framework, f.ex. Dig?
+				if cfg.Listener != nil {
+					s.log.Debug("Using provided listener for HTTP server")
+					httpS.Listener = cfg.Listener
+				}
+			}
+		}
 		if err := service.Instance.Init(); err != nil {
 			return errutil.Wrapf(err, "Service init failed")
 		}
 	}
 
+	return nil
+}
+
+// Run initializes and starts services. This will block until all services have
+// exited. To initiate shutdown, call the Shutdown method in another goroutine.
+func (s *Server) Run() (err error) {
+	if err = s.init(nil); err != nil {
+		return
+	}
+
+	services := registry.GetServices()
+
 	// Start background services.
 	for _, svc := range services {
 		service, ok := svc.Instance.(registry.BackgroundService)
@@ -157,7 +209,7 @@ func (s *Server) Run() (err error) {
 
 	s.notifySystemd("READY=1")
 
-	return err
+	return nil
 }
 
 func (s *Server) Shutdown(reason string) {
@@ -257,9 +309,9 @@ func (s *Server) loadConfiguration() {
 	}
 
 	s.log.Info("Starting "+setting.ApplicationName,
-		"version", version,
-		"commit", commit,
-		"branch", buildBranch,
+		"version", s.version,
+		"commit", s.commit,
+		"branch", s.buildBranch,
 		"compiled", time.Unix(setting.BuildStamp, 0),
 	)