A client/server helper wrapper for endpoints in Go.

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

+// 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.
+}