Merge pull request #18587 from calavera/daemon_configuration_file

Allow to set daemon and server configurations in a file.
Upstream-commit: e44364eae90784b423eee8b2969bda9cd2429746
Component: engine

components/engine/api/server/router_swapper.go

@@ -0,0 +1,30 @@
+package server
+
+import (
+	"net/http"
+	"sync"
+
+	"github.com/gorilla/mux"
+)
+
+// routerSwapper is an http.Handler that allow you to swap
+// mux routers.
+type routerSwapper struct {
+	mu     sync.Mutex
+	router *mux.Router
+}
+
+// Swap changes the old router with the new one.
+func (rs *routerSwapper) Swap(newRouter *mux.Router) {
+	rs.mu.Lock()
+	rs.router = newRouter
+	rs.mu.Unlock()
+}
+
+// ServeHTTP makes the routerSwapper to implement the http.Handler interface.
+func (rs *routerSwapper) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	rs.mu.Lock()
+	router := rs.router
+	rs.mu.Unlock()
+	router.ServeHTTP(w, r)
+}

components/engine/api/server/server.go

@@ -4,7 +4,6 @@ import (
 	"crypto/tls"
 	"net"
 	"net/http"
-	"os"
 	"strings"
 
 	"github.com/Sirupsen/logrus"
@@ -42,10 +41,11 @@ type Config struct {
 
 // Server contains instance details for the server
 type Server struct {
-	cfg          *Config
-	servers      []*HTTPServer
-	routers      []router.Router
-	authZPlugins []authorization.Plugin
+	cfg           *Config
+	servers       []*HTTPServer
+	routers       []router.Router
+	authZPlugins  []authorization.Plugin
+	routerSwapper *routerSwapper
 }
 
 // Addr contains string representation of address and its protocol (tcp, unix...).
@@ -80,12 +80,14 @@ func (s *Server) Close() {
 	}
 }
 
-// ServeAPI loops through all initialized servers and spawns goroutine
-// with Server method for each. It sets CreateMux() as Handler also.
-func (s *Server) ServeAPI() error {
+// serveAPI loops through all initialized servers and spawns goroutine
+// with Server method for each. It sets createMux() as Handler also.
+func (s *Server) serveAPI() error {
+	s.initRouterSwapper()
+
 	var chErrors = make(chan error, len(s.servers))
 	for _, srv := range s.servers {
-		srv.srv.Handler = s.CreateMux()
+		srv.srv.Handler = s.routerSwapper
 		go func(srv *HTTPServer) {
 			var err error
 			logrus.Infof("API listen on %s", srv.l.Addr())
@@ -186,11 +188,11 @@ func (s *Server) addRouter(r router.Router) {
 	s.routers = append(s.routers, r)
 }
 
-// CreateMux initializes the main router the server uses.
+// createMux initializes the main router the server uses.
 // we keep enableCors just for legacy usage, need to be removed in the future
-func (s *Server) CreateMux() *mux.Router {
+func (s *Server) createMux() *mux.Router {
 	m := mux.NewRouter()
-	if os.Getenv("DEBUG") != "" {
+	if utils.IsDebugEnabled() {
 		profilerSetup(m, "/debug/")
 	}
 
@@ -207,3 +209,36 @@ func (s *Server) CreateMux() *mux.Router {
 
 	return m
 }
+
+// Wait blocks the server goroutine until it exits.
+// It sends an error message if there is any error during
+// the API execution.
+func (s *Server) Wait(waitChan chan error) {
+	if err := s.serveAPI(); err != nil {
+		logrus.Errorf("ServeAPI error: %v", err)
+		waitChan <- err
+		return
+	}
+	waitChan <- nil
+}
+
+func (s *Server) initRouterSwapper() {
+	s.routerSwapper = &routerSwapper{
+		router: s.createMux(),
+	}
+}
+
+// Reload reads configuration changes and modifies the
+// server according to those changes.
+// Currently, only the --debug configuration is taken into account.
+func (s *Server) Reload(config *daemon.Config) {
+	debugEnabled := utils.IsDebugEnabled()
+	switch {
+	case debugEnabled && !config.Debug: // disable debug
+		utils.DisableDebug()
+		s.routerSwapper.Swap(s.createMux())
+	case config.Debug && !debugEnabled: // enable debug
+		utils.EnableDebug()
+		s.routerSwapper.Swap(s.createMux())
+	}
+}