A client/server helper wrapper for endpoints in Go.

go/src/infra/gae/epclient/epclient.go

Index: go/src/infra/gae/epclient/epclient.go
diff --git a/go/src/infra/gae/epclient/epclient.go b/go/src/infra/gae/epclient/epclient.go
new file mode 100644
index 0000000000000000000000000000000000000000..3475a77561571350495733d88d8080f0fb53aa37
--- /dev/null
+++ b/go/src/infra/gae/epclient/epclient.go
@@ -0,0 +1,113 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// The following comment allows `go generate` to correctly generate clients
+// for all endpoints services located in the "infra/gae/epservice" package.
+//go:generate goapp run epclient.go
+
+// EPClient will auto-generate endpoints clients from Google Cloud Endpoint
+// service definitions. The tool assumes that:
+//   * all go endpoint service definitions occur in a package which has
+//     a public method `RegisterEndpointsService(*endpoints.Server) error`, and
+//     that calling this method will register the endpoints service with the
+//     provided server or return an error.
+//   * goapp exists in PATH (and understands all the import paths in the
+//     defined services)
+//   * google-api-go-generator exists in PATH.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+)
+
+var (
+	servicePackagesBase = flag.String("pkgs", "infra",
+		"base Go package to walk to find service definitions.")
+	outDir = flag.String("outdir", ".",
+		"The directory to generate the client libraries in.")
+)
+
+const discoveryURL = "http://localhost:8080/_ah/api/discovery/v1/apis"
+
+func boom(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func parseFlags() {
+	var err error
+	flag.Parse()
+	if *outDir == "" {
+		if *outDir, err = os.Getwd(); err != nil {
+			panic(err)
+		}
+	}
+	if *outDir, err = filepath.Abs(*outDir); err != nil {
+		panic(err)
+	}
+}
+
+func startServer() func() {
+	boom(exec.Command("goapp", "install", "infra/gae/epservice").Run())
+	server := exec.Command("epservice", "-base", *servicePackagesBase)
+	server.Stdout = os.Stdout
+	server.Stderr = os.Stderr
+	if err := server.Start(); err != nil {
+		panic(err)
+	}
+
+	deadline := time.Now().Add(time.Second * 5)
+	for {
+		if time.Now().After(deadline) {
+			panic("waited too long for server to start!")
+		}
+		rsp, err := http.Get(discoveryURL)
+		if err == nil && rsp.StatusCode == 200 {
+			break
+		}
+		time.Sleep(time.Millisecond * 200)
+	}
+	fmt.Println("Discovery service up")
+
+	return func() {
+		server.Process.Signal(os.Interrupt)
+		server.Wait()
+	}
+}
+
+func generate() {
+	gencmd := exec.Command("google-api-go-generator", "-discoveryurl", discoveryURL, "-gendir", *outDir, "-cache=false")
+	gencmd.Stdout = os.Stdout
+	gencmd.Stderr = os.Stderr
+	if err := gencmd.Run(); err != nil {
+		panic(err)
+	}
+}
+
+func mustHave(executable string) {
+	_, err := exec.LookPath(executable)
+	if err != nil {
+		panic(executable + " must be on your path")
+	}
+}
+
+func main() {
+	mustHave("goapp")
+	mustHave("google-api-go-generator")
+
+	parseFlags()
+
+	stop := startServer()
+	defer stop()
+	generate()
+
+	// inject DoWithRetries methods.
+}