Add directory ownership and enable ephemeral ports

BUILD.bazel

@@ -21,6 +21,7 @@ go_library(
         "//config:go_default_library",
         "//server:go_default_library",
         "@com_github_abbot_go_http_auth//:go_default_library",
+        "@com_github_nightlyone_lockfile//:go_default_library",
         "@com_github_urfave_cli//:go_default_library",
     ],
 )

WORKSPACE

@@ -39,8 +39,8 @@ gazelle_dependencies()
 
 go_repository(
     name = "com_github_abbot_go_http_auth",
-    commit = "0ddd408d5d60ea76e320503cc7dd091992dee608",
     importpath = "github.com/abbot/go-http-auth",
+    tag = "v0.4.0",
 )
 
 go_repository(
@@ -51,49 +51,49 @@ go_repository(
 
 go_repository(
     name = "com_github_djherbis_atime",
-    commit = "8e47e0e01d08df8b9f840d74299c8ab70a024a30",
     importpath = "github.com/djherbis/atime",
+    tag = "v1.0.0",
 )
 
 go_repository(
     name = "org_golang_x_crypto",
-    commit = "ab813273cd59e1333f7ae7bff5d027d4aadf528c",
+    commit = "ab813273cd59",
     importpath = "golang.org/x/crypto",
 )
 
 go_repository(
     name = "org_golang_x_net",
-    commit = "1e491301e022f8f977054da4c2d852decd59571f",
+    commit = "1e491301e022",
     importpath = "golang.org/x/net",
 )
 
 go_repository(
     name = "com_github_golang_protobuf",
-    commit = "b4deda0973fb4c70b50d226b1af49f3da59f5265",
     importpath = "github.com/golang/protobuf",
+    tag = "v1.1.0",
 )
 
 go_repository(
     name = "com_google_cloud_go",
-    commit = "0fd7230b2a7505833d5f69b75cbd6c9582401479",
     importpath = "cloud.google.com/go",
+    tag = "v0.23.0",
 )
 
 go_repository(
     name = "in_gopkg_yaml_v2",
-    commit = "5420a8b6744d3b0345ab293f6fcba19c978f1183",
     importpath = "gopkg.in/yaml.v2",
+    tag = "v2.2.1",
 )
 
 go_repository(
     name = "org_golang_google_appengine",
-    commit = "150dc57a1b433e64154302bdc40b6bb8aefa313a",
     importpath = "google.golang.org/appengine",
+    tag = "v1.0.0",
 )
 
 go_repository(
     name = "org_golang_x_oauth2",
-    commit = "ec22f46f877b4505e0117eeaab541714644fdd28",
+    commit = "ec22f46f877b",
     importpath = "golang.org/x/oauth2",
 )
 
@@ -105,6 +105,18 @@ go_repository(
 
 go_repository(
     name = "com_github_google_go_cmp",
-    commit = "3af367b6b30c263d47e8895973edcca9a49cf029",
     importpath = "github.com/google/go-cmp",
+    tag = "v0.2.0",
+)
+
+go_repository(
+    name = "com_github_nightlyone_lockfile",
+    commit = "0ad87eef1443",
+    importpath = "github.com/nightlyone/lockfile",
+)
+
+go_repository(
+    name = "in_gopkg_check_v1",
+    commit = "20d25e280405",
+    importpath = "gopkg.in/check.v1",
 )

config/config.go

@@ -96,7 +96,7 @@ func validateConfig(c *Config) error {
 		return errors.New("The 'max_size' flag/key must be set to a value > 0")
 	}
 
-	if c.Port == 0 {
+	if c.Port < 0 {
 		return errors.New("A valid 'port' flag/key must be specified")
 	}
 

go.mod

@@ -1,15 +1,16 @@
 module github.com/buchgr/bazel-remote
 
 require (
-	cloud.google.com/go v0.23.0
+	cloud.google.com/go v0.23.0 // indirect
 	github.com/abbot/go-http-auth v0.4.0
 	github.com/djherbis/atime v1.0.0
-	github.com/golang/protobuf v1.1.0
+	github.com/golang/protobuf v1.1.0 // indirect
 	github.com/google/go-cmp v0.2.0
+	github.com/nightlyone/lockfile v0.0.0-20180618180623-0ad87eef1443
 	github.com/urfave/cli v1.20.0
-	golang.org/x/crypto v0.0.0-20180527072434-ab813273cd59
-	golang.org/x/net v0.0.0-20180530234432-1e491301e022
+	golang.org/x/crypto v0.0.0-20180527072434-ab813273cd59 // indirect
+	golang.org/x/net v0.0.0-20180530234432-1e491301e022 // indirect
 	golang.org/x/oauth2 v0.0.0-20180529203656-ec22f46f877b
-	google.golang.org/appengine v1.0.0
+	google.golang.org/appengine v1.0.0 // indirect
 	gopkg.in/yaml.v2 v2.2.1
 )

go.sum

@@ -4,8 +4,12 @@ github.com/abbot/go-http-auth v0.4.0 h1:QjmvZ5gSC7jm3Zg54DqWE/T5m1t2AfDu6QlXJT0E
 github.com/abbot/go-http-auth v0.4.0/go.mod h1:Cz6ARTIzApMJDzh5bRMSUou6UMSp0IEXg9km/ci7TJM=
 github.com/djherbis/atime v1.0.0 h1:ySLvBAM0EvOGaX7TI4dAM5lWj+RdJUCKtGSEHN8SGBg=
 github.com/djherbis/atime v1.0.0/go.mod h1:5W+KBIuTwVGcqjIfaTwt+KSYX1o6uep8dtevevQP/f8=
+github.com/golang/protobuf v1.1.0 h1:0iH4Ffd/meGoXqF2lSAhZHt8X+cPgkfn/cb6Cce5Vpc=
 github.com/golang/protobuf v1.1.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/nightlyone/lockfile v0.0.0-20180618180623-0ad87eef1443 h1:+2OJrU8cmOstEoh0uQvYemRGVH1O6xtO2oANUWHFnP0=
+github.com/nightlyone/lockfile v0.0.0-20180618180623-0ad87eef1443/go.mod h1:JbxfV1Iifij2yhRjXai0oFrbpxszXHRx1E5RuM26o4Y=
 github.com/urfave/cli v1.20.0 h1:fDqGv3UG/4jbVl/QkFwEdddtEDjh/5Ov6X+0B/3bPaw=
 github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
 golang.org/x/crypto v0.0.0-20180527072434-ab813273cd59 h1:hk3yo72LXLapY9EXVttc3Z1rLOxT9IuAPPX3GpY2+jo=
@@ -14,6 +18,7 @@ golang.org/x/net v0.0.0-20180530234432-1e491301e022 h1:MVYFTUmVD3/+ERcvRRI+P/C2+
 golang.org/x/net v0.0.0-20180530234432-1e491301e022/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/oauth2 v0.0.0-20180529203656-ec22f46f877b h1:nCwwlzLoBQhkY/S3CJ2CGAU4pYfR8+5/TPGEHT+p5Nk=
 golang.org/x/oauth2 v0.0.0-20180529203656-ec22f46f877b/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
+google.golang.org/appengine v1.0.0 h1:dN4LljjBKVChsv0XCSI+zbyzdqrkEwX5LQFUMRSGqOc=
 google.golang.org/appengine v1.0.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=

main.go

@@ -3,12 +3,18 @@ package main
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
 	"log"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
+	"os/signal"
+	"path/filepath"
 	"strconv"
+	"strings"
 	"sync"
+	"syscall"
 	"time"
 
 	auth "github.com/abbot/go-http-auth"
@@ -20,9 +26,46 @@ import (
 
 	"github.com/buchgr/bazel-remote/config"
 	"github.com/buchgr/bazel-remote/server"
+	"github.com/nightlyone/lockfile"
 	"github.com/urfave/cli"
 )
 
+const bazelRemotePidFile = "bazel-remote.pid"
+
+var signalHandlers []func(os.Signal)
+var signalHandlersMutex sync.Mutex
+
+//http server.go doesn't export tcpKeepAliveListener so we have to do the same here
+type tcpKeepAliveListener struct {
+	*net.TCPListener
+}
+
+func (ln tcpKeepAliveListener) Accept() (net.Conn, error) {
+	tc, err := ln.AcceptTCP()
+	if err != nil {
+		return nil, err
+	}
+	tc.SetKeepAlive(true)
+	tc.SetKeepAlivePeriod(3 * time.Minute)
+	return tc, nil
+}
+
+func init() {
+	// set up a signal handler to clean up if we are interrupted
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		select {
+		case sig := <-c:
+			signalHandlersMutex.Lock()
+			defer signalHandlersMutex.Unlock()
+			for _, fn := range signalHandlers {
+				fn(sig)
+			}
+		}
+	}()
+}
+
 func main() {
 	app := cli.NewApp()
 	app.Description = "A remote build cache for Bazel."
@@ -118,6 +161,30 @@ func main() {
 		accessLogger := log.New(os.Stdout, "", log.Ldate|log.Ltime|log.LUTC)
 		errorLogger := log.New(os.Stderr, "", log.Ldate|log.Ltime|log.LUTC)
 
+		if err := os.MkdirAll(c.Dir, 0755); err != nil {
+			return err
+		}
+		lockAbsPath, err := filepath.Abs(filepath.Join(c.Dir, bazelRemotePidFile))
+		if err != nil {
+			return err
+		}
+		pidFileLock, err := lockfile.New(lockAbsPath)
+		if err != nil {
+			return err
+		}
+		err = pidFileLock.TryLock()
+		if err != nil {
+			if err == lockfile.ErrBusy {
+				pid, _ := ioutil.ReadFile(lockAbsPath)
+				return fmt.Errorf(
+					"Already locked by pid %v",
+					strings.Trim(string(pid), "\n"),
+				)
+			}
+			return fmt.Errorf("Could not lock %v: %v", c.Dir, err)
+		}
+		defer pidFileLock.Unlock()
+
 		diskCache := disk.New(c.Dir, int64(c.MaxSize)*1024*1024*1024)
 
 		var proxyCache cache.Cache
@@ -142,33 +209,76 @@ func main() {
 
 		mux := http.NewServeMux()
 		httpServer := &http.Server{
-			Addr:    c.Host + ":" + strconv.Itoa(c.Port),
 			Handler: mux,
 		}
+
+		// graceful shutdown on signal
+		func() {
+			signalHandlersMutex.Lock()
+			defer signalHandlersMutex.Unlock()
+			signalHandlers = append(signalHandlers, func(sig os.Signal) {
+				errorLogger.Printf("Shutting down server due to signal: %v", sig)
+				if err := httpServer.Shutdown(context.Background()); err != nil {
+					errorLogger.Printf("Failed to shutdown http server: %v", err)
+				}
+			})
+		}()
+
 		h := server.NewHTTPCache(proxyCache, accessLogger, errorLogger)
 		mux.HandleFunc("/status", h.StatusPageHandler)
 
 		cacheHandler := h.CacheHandler
 		if c.HtpasswdFile != "" {
 			cacheHandler = wrapAuthHandler(cacheHandler, c.HtpasswdFile, c.Host)
 		}
+
 		if c.IdleTimeout > 0 {
 			cacheHandler = wrapIdleHandler(cacheHandler, c.IdleTimeout, accessLogger, httpServer)
 		}
+
 		mux.HandleFunc("/", cacheHandler)
+		ln, err := net.Listen("tcp", c.Host+":"+strconv.Itoa(c.Port))
+		if err != nil {
+			return err
+		}
+		defer ln.Close()
+
+		// create a unix domain socket and respond with the port when asked
+		bazelRemoteSocketPath := filepath.Join(c.Dir, fmt.Sprintf("bazel-remote.%d.sock", os.Getpid()))
+		sock, err := net.Listen("unix", bazelRemoteSocketPath)
+		if err != nil {
+			return err
+		}
+		defer os.Remove(bazelRemoteSocketPath)
+		go handlePortRequest(sock, ln.Addr(), errorLogger)
 
 		if len(c.TLSCertFile) > 0 && len(c.TLSKeyFile) > 0 {
-			return httpServer.ListenAndServeTLS(c.TLSCertFile, c.TLSKeyFile)
+			return httpServer.ServeTLS(tcpKeepAliveListener{ln.(*net.TCPListener)}, c.TLSCertFile, c.TLSKeyFile)
 		}
-		return httpServer.ListenAndServe()
+		return httpServer.Serve(tcpKeepAliveListener{ln.(*net.TCPListener)})
 	}
-
 	serverErr := app.Run(os.Args)
 	if serverErr != nil {
 		log.Fatal("bazel-remote terminated: ", serverErr)
 	}
 }
 
+func handlePortRequest(sock net.Listener, addr net.Addr, errorLogger *log.Logger) {
+	for {
+		fd, err := sock.Accept()
+		if err != nil {
+			errorLogger.Printf("sock: %v", err)
+			continue
+		}
+		if _, err := fd.Write([]byte(addr.String() + "\n")); err != nil {
+			errorLogger.Printf("sock write: %v", err)
+		}
+		if err := fd.Close(); err != nil {
+			errorLogger.Printf("sock close: %v", err)
+		}
+	}
+}
+
 func wrapIdleHandler(handler http.HandlerFunc, idleTimeout time.Duration, accessLogger cache.Logger, httpServer *http.Server) http.HandlerFunc {
 	lastRequest := time.Now()
 	ticker := time.NewTicker(time.Second)