func()

in v2/aetest/instance.go [203:325]
113 lines of code
33 McCabe index (conditional complexity)

func (i *instance) startChild() (err error) {
	if PrepareDevAppserver != nil {
		if err := PrepareDevAppserver(); err != nil {
			return err
		}
	}
	executable := os.Getenv("APPENGINE_DEV_APPSERVER_BINARY")
	var appserverArgs []string
	if len(executable) == 0 {
		executable, err = findPython()
		if err != nil {
			return fmt.Errorf("Could not find python interpreter: %v", err)
		}
		devAppserver, err := findDevAppserver()
		if err != nil {
			return fmt.Errorf("Could not find dev_appserver.py: %v", err)
		}
		appserverArgs = append(appserverArgs, devAppserver)
	}

	i.appDir, err = ioutil.TempDir("", "appengine-aetest")
	if err != nil {
		return err
	}
	defer func() {
		if err != nil {
			os.RemoveAll(i.appDir)
		}
	}()
	err = os.Mkdir(filepath.Join(i.appDir, "app"), 0755)
	if err != nil {
		return err
	}
	err = ioutil.WriteFile(filepath.Join(i.appDir, "app", "app.yaml"), []byte(i.appYAML()), 0644)
	if err != nil {
		return err
	}
	err = ioutil.WriteFile(filepath.Join(i.appDir, "app", "stubapp.go"), []byte(appSource), 0644)
	if err != nil {
		return err
	}

	appserverArgs = append(appserverArgs,
		"--port=0",
		"--api_port=0",
		"--admin_port=0",
		"--automatic_restart=false",
		"--skip_sdk_update_check=true",
		"--clear_datastore=true",
		"--clear_search_indexes=true",
		"--datastore_path", filepath.Join(i.appDir, "datastore"),
	)
	if i.opts != nil && i.opts.StronglyConsistentDatastore {
		appserverArgs = append(appserverArgs, "--datastore_consistency_policy=consistent")
	}
	if i.opts != nil && i.opts.SupportDatastoreEmulator != nil {
		appserverArgs = append(appserverArgs, fmt.Sprintf("--support_datastore_emulator=%t", *i.opts.SupportDatastoreEmulator))
	}
	appserverArgs = append(appserverArgs, filepath.Join(i.appDir, "app"))

	i.child = exec.Command(executable, appserverArgs...)

	i.child.Stdout = os.Stdout
	var stderr io.Reader
	stderr, err = i.child.StderrPipe()
	if err != nil {
		return err
	}

	if err = i.child.Start(); err != nil {
		return err
	}

	// Read stderr until we have read the URLs of the API server and admin interface.
	errc := make(chan error, 1)
	go func() {
		s := bufio.NewScanner(stderr)
		for s.Scan() {
			// Pass stderr along as we go so the user can see it.
			if !(i.opts != nil && i.opts.SuppressDevAppServerLog) {
				fmt.Fprintln(os.Stderr, s.Text())
			}
			if match := apiServerAddrRE.FindStringSubmatch(s.Text()); match != nil {
				u, err := url.Parse(match[1])
				if err != nil {
					errc <- fmt.Errorf("failed to parse API URL %q: %v", match[1], err)
					return
				}
				i.apiURL = u
			}
			if match := adminServerAddrRE.FindStringSubmatch(s.Text()); match != nil {
				i.adminURL = match[1]
			}
			if i.adminURL != "" && i.apiURL != nil {
				// Pass along stderr to the user after we're done with it.
				if !(i.opts != nil && i.opts.SuppressDevAppServerLog) {
					go io.Copy(os.Stderr, stderr)
				}
				break
			}
		}
		errc <- s.Err()
	}()

	select {
	case <-time.After(i.startupTimeout):
		if p := i.child.Process; p != nil {
			p.Kill()
		}
		return errors.New("timeout starting child process")
	case err := <-errc:
		if err != nil {
			return fmt.Errorf("error reading child process stderr: %v", err)
		}
	}
	if i.adminURL == "" {
		return errors.New("unable to find admin server URL")
	}
	if i.apiURL == nil {
		return errors.New("unable to find API server URL")
	}
	return nil
}