A client/server helper wrapper for endpoints in Go.

go/src/infra/gae/epservice/epservice.go

Index: go/src/infra/gae/epservice/epservice.go
diff --git a/go/src/infra/gae/epservice/epservice.go b/go/src/infra/gae/epservice/epservice.go
new file mode 100644
index 0000000000000000000000000000000000000000..582fc44dd9103adc1dad33201b16425aacd0879a
--- /dev/null
+++ b/go/src/infra/gae/epservice/epservice.go
@@ -0,0 +1,250 @@
+// 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.
+
+// EPService will run a local appengine service with all of the endpoint
+// services under this directory. The tool assumes that:
+//   * goapp exists in PATH (and understands all the import paths in the
+//     defined services)
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"sync"
+	"text/template"
+	"time"
+
+	"infra/libs/jsutil"
+)
+
+var (
+	clearDatastore      = flag.Bool("clear_datastore", false, "if set, clear the datastore.")
+	leak                = flag.Bool("leak", false, "if set, leak the temporary directory.")
+	verbose             = flag.Bool("verbose", false, "if set, print skipped packages.")
+	servicePackagesBase = flag.String("base", "infra",
+		"base Go package to walk to find service definitions.")
+)
+
+var serviceScript = `{{define "go"}}
+// DO NOT EDIT
+// Auto-generated by infra/gae/epservice
+// {{.Timestamp}}
+
+package main
+
+import (
+	"fmt"
+
+{{range $idx, $pkg := .Pkgs}}
+	pkg{{$idx}} "{{$pkg.Imp}}"{{end}}
+
+	"github.com/GoogleCloudPlatform/go-endpoints/endpoints"
+)
+
+func init() {
+	var err error
+	server := endpoints.NewServer("")
+
+	{{range $idx, $pkg := .Pkgs }}
+	err = pkg{{$idx}}.RegisterEndpointsService(server)
+	if err != nil {
+		panic(fmt.Errorf("Error while registering service {{$pkg}}: %s", err))
+	}
+	{{end}}
+
+	server.HandleHTTP(nil)
+}
+{{end}}
+`
+
+const appYaml = `{{define "yaml"}}
+# DO NOT EDIT
+# Auto-generated by infra/gae/epservice
+# {{.Timestamp}}
+
+application: epclient-tmp-app
+version: nope
+runtime: go
+api_version: go1
+
+handlers:
+- url: /.*
+  script: _go_app
+{{end}}
+`
+
+var templ = template.New("service")
+
+func init() {
+	template.Must(templ.Parse(serviceScript))
+	template.Must(templ.Parse(appYaml))
+}
+
+type templInput struct {
+	Pkgs      []Pkg
+	Timestamp time.Time
+}
+
+// Pkg holds the import and real filesystem paths of an endpoint service
+// package. It's exported merely for reflection purposes, since it's used
+// by text/template.
+type Pkg struct {
+	Imp string
+	Pth string
+}
+
+func boom(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+// NOTE: if you format your RegisterEndpointsService implementation like a bozo,
+// then this won't match. Don't do that.
+var reRegisterEndpointsService = regexp.MustCompile(
+	`\nfunc RegisterEndpointsService\(\w* \*\w*\.Server\) error {\n`)
+
+func getPkgs() []Pkg {
+	cmd := exec.Command("goapp", "list", "-json", filepath.Join(*servicePackagesBase+"..."))
+	d, err := cmd.Output()
+	boom(err)
+
+	d = []byte("[" + strings.Replace(string(d), "}\n{", "},{", -1) + "]")
+
+	js := interface{}(nil)
+	boom(json.Unmarshal(d, &js))
+
+	ret := []Pkg{}
+
+	type pkgOk struct {
+		p  Pkg
+		ok bool
+	}
+	pkgs := make(chan pkgOk)
+	wg := sync.WaitGroup{}
+
+	for _, m := range js.([]interface{}) {
+		pkg := Pkg{
+			jsutil.Get(m, "ImportPath").(string),
+			jsutil.Get(m, "Dir").(string),
+		}
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			paths, err := ioutil.ReadDir(pkg.Pth)
+			boom(err)
+
+			for _, f := range paths {
+				if !f.IsDir() && strings.HasSuffix(f.Name(), ".go") {
+					data, err := ioutil.ReadFile(filepath.Join(pkg.Pth, f.Name()))
+					boom(err)
+					if reRegisterEndpointsService.Match(data) {
+						pkgs <- pkgOk{pkg, true}
+						return
+					}
+				}
+			}
+			pkgs <- pkgOk{pkg, false}
+		}()
+	}
+	go func() {
+		wg.Wait()
+		close(pkgs)
+	}()
+
+	for p := range pkgs {
+		if !p.ok {
+			if *verbose {
+				fmt.Println("skipping package", p.p.Imp, "(it doesn't impliment RegisterEndpointsService?)")
+			}
+		} else {
+			fmt.Println("including package", p.p.Imp)
+			ret = append(ret, p.p)
+		}
+	}
+
+	return ret
+}
+
+func writeFiles(dir string, pkgs []Pkg) {
+	input := &templInput{pkgs, time.Now()}
+	for _, ext := range []string{"go", "yaml"} {
+		buf := &bytes.Buffer{}
+		boom(templ.ExecuteTemplate(buf, ext, input))
+		boom(ioutil.WriteFile(filepath.Join(dir, "app."+ext), buf.Bytes(), 0666))
+	}
+}
+
+func startServer(dir string) (func(), func()) {
+	args := []string{"serve"}
+	if *clearDatastore {
+		args = append(args, "-clear_datastore")
+	}
+	args = append(args, dir)
+	server := exec.Command("goapp", args...)
+	server.Stdout = os.Stdout
+	server.Stderr = os.Stderr
+	boom(server.Start())
+
+	wait := func() { server.Wait() }
+	stop := func() {
+		server.Process.Signal(os.Interrupt)
+		wait()
+	}
+	return stop, wait
+}
+
+func main() {
+	_, err := exec.LookPath("goapp")
+	if err != nil {
+		panic("goapp must be on your path")
+	}
+
+	flag.Parse()
+	pkgs := getPkgs()
+
+	dir, err := ioutil.TempDir("", "epservice_gen")
+	boom(err)
+	prefix := "LEAKING"
+	if !*leak {
+		prefix = "generating"
+		defer os.RemoveAll(dir)
+	}
+	fmt.Println(prefix, "files in:", dir)
+
+	writeFiles(dir, pkgs)
+
+	stop, wait := startServer(dir)
+	defer wait()
+
+	intC := make(chan os.Signal, 1)

[dnj, 2015/06/09 02:56:58]

Way less cute of a channel name :(

+	signal.Notify(intC, os.Interrupt, os.Kill)
+	sigC := make(chan struct{})
+	go func() {
+		defer close(sigC)
+		<-intC
+		stop()
+	}()
+
+	waitC := make(chan struct{})
+	go func() {
+		defer close(waitC)
+		wait()
+	}()
+
+	select {
+	case <-sigC:
+	case <-waitC:
+	}
+	time.Sleep(time.Second)

[dnj, 2015/06/09 02:56:58]

Why is this necessary?

[iannucci, 2015/06/09 07:41:11]

added it while I was debugging something else. The `defer` above should have
been wait() and not stop() (now it's fixed). Otherwise we were partially killing
off dev_appserver, then deleting the tempdir underneath the rest of it.

That said... all of this code was racy and wrong. The exec.Command wasn't
creating the child with its own process group id, which means that dev_appserver
(and everything below it) was getting signaled twice every time. Racy and bad.

New version is much better.

+}