add --stub-watch option

Readme.md

@@ -77,6 +77,8 @@ mount your stub file in `/mystubs` folder then mount it to docker like
  `docker run -p 4770:4770 -p 4771:4771 -v /mypath:/proto -v /mystubs:/stub tkpd/gripmock --stub=/stub /proto/hello.proto`
 
 Please note that Gripmock still serves http stubbing to modify stored stubs on the fly.
+
+You may pass `--stub-watch` option to watch changes in the stub directory. When you edit a file in the directory, it will clean the stubs and load all files in the directory again to make your changes available.
 
 ## <a name="input_matching"></a>Input Matching
 Stub will respond with the expected response only if the request matches any rule. Stub service will serve `/find` endpoint with format:

go.mod

@@ -3,6 +3,7 @@ module github.com/tokopedia/gripmock
 go 1.15
 
 require (
+	github.com/fsnotify/fsnotify v1.4.9
 	github.com/go-chi/chi v4.1.2+incompatible
 	github.com/gobuffalo/here v0.6.2 // indirect
 	github.com/golang/protobuf v1.4.3

gripmock.go

@@ -20,6 +20,7 @@ func main() {
 	adminport := flag.String("admin-port", "4771", "Port of stub admin server")
 	adminBindAddr := flag.String("admin-listen", "", "Adress the admin server will bind to. Default to localhost, set to 0.0.0.0 to use from another machine")
 	stubPath := flag.String("stub", "", "Path where the stub files are (Optional)")
+	stubWatch := flag.Bool("stub-watch", false, "watch the stub directory for change")
 	imports := flag.String("imports", "/protobuf", "comma separated imports path. default path /protobuf is where gripmock Dockerfile install WKT protos")
 	// for backwards compatibility
 	if os.Args[1] == "gripmock" {
@@ -45,9 +46,10 @@ func main() {
 
 	// run admin stub server
 	stub.RunStubServer(stub.Options{
-		StubPath: *stubPath,
-		Port:     *adminport,
-		BindAddr: *adminBindAddr,
+		StubPath:  *stubPath,
+		StubWatch: *stubWatch,
+		Port:      *adminport,
+		BindAddr:  *adminBindAddr,
 	})
 
 	// parse proto files

stub/storage.go

@@ -9,6 +9,7 @@ import (
 	"regexp"
 	"sync"
 
+	"github.com/fsnotify/fsnotify"
 	"github.com/lithammer/fuzzysearch/fuzzy"
 )
 
@@ -285,3 +286,39 @@ func readStubFromFile(path string) {
 		storeStub(stub)
 	}
 }
+
+func watchStubDir(path string) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		log.Printf("Error when watching the stub directory. %v.", err)
+		return
+	}
+	defer watcher.Close()
+
+	done := make(chan bool)
+	go func() {
+		for {
+			select {
+			case event, ok := <-watcher.Events:
+				if !ok {
+					return
+				}
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					clearStorage()
+					readStubFromFile(path)
+				}
+			case err, ok := <-watcher.Errors:
+				if !ok {
+					return
+				}
+				log.Printf("Error when watching the stub directory. %v.", err)
+			}
+		}
+	}()
+
+	err = watcher.Add(path)
+	if err != nil {
+		log.Printf("Error when watching the stub directory %s. %v.", path, err)
+	}
+	<-done
+}

stub/stub.go

@@ -7,14 +7,15 @@ import (
 	"log"
 	"net/http"
 	"strings"
-	
+
 	"github.com/go-chi/chi"
 )
 
 type Options struct {
-	Port     string
-	BindAddr string
-	StubPath string
+	Port      string
+	BindAddr  string
+	StubPath  string
+	StubWatch bool
 }
 
 const DEFAULT_PORT = "4771"
@@ -32,6 +33,13 @@ func RunStubServer(opt Options) {
 
 	if opt.StubPath != "" {
 		readStubFromFile(opt.StubPath)
+
+		if opt.StubWatch {
+			fmt.Println("Watching for changes in " + opt.StubPath)
+			go func() {
+				watchStubDir(opt.StubPath)
+			}()
+		}
 	}
 
 	fmt.Println("Serving stub admin on http://" + addr)