Quickstart for Go in the App Engine Flexible Environment

This quickstart shows you how to create a small App Engine application that displays a short message.

Before you begin

Before running this sample, take the following steps:

  1. Use the Cloud Platform Console to create a new Cloud Platform project, create an App Engine application, and enable billing:
    Go to App Engine

    When prompted, select the region where you want your App Engine application located and then enable billing.

  2. Install the following prerequisites locally:
    1. Download and install git.
    2. Download, install, and initialize the Google Cloud SDK:
      Download the SDK
    3. Install the aedeploy tool:
      go get google.golang.org/appengine/cmd/aedeploy
  3. Alternatively: You can use Google Cloud Shell, which comes with these prerequisites already installed.

This quickstart assumes that you are familiar with the Go programming language and that you have installed Go.

Download the Hello World app

We've created a simple Hello World app for Go so you can quickly get a feel for deploying an app to Google Cloud Platform. Follow these steps from a command line to download Hello World to your local machine.

Download the sample app and navigate into the app directory:

  1. Get the Hello World sample app and its dependencies:

    go get -u -d github.com/GoogleCloudPlatform/golang-samples/appengine_flexible/helloworld
    

  2. Change to the directory that contains the sample code:

    cd $GOPATH/src/github.com/GoogleCloudPlatform/golang-samples/appengine_flexible/helloworld
    

Run Hello World on your local machine

To run the Hello World app on your local computer:

  1. Start a local web server:

    go run *.go
    
  2. In your web browser, enter the following address:

    http://localhost:8080
    
You can see the Hello World message from the sample app displayed in the page.

In your terminal window, press Ctrl+C to exit the web server.

Deploy and run Hello World on App Engine

To deploy your app to the App Engine flexible environment:

  1. Deploy the Hello World app by running the following command from the helloworld directory:
    aedeploy gcloud app deploy
  2. Visit the following address to see your deployed app:
    https://[YOUR_PROJECT_ID].appspot.com

This time, the page that displays the Hello World message is delivered by a web server running on an App Engine instance.

Congratulations! You've deployed your first Go app to App Engine flexible environment!

Clean up

To avoid incurring charges to your Google Cloud Platform account for the resources used in this quickstart:

  1. Go to the Cloud Platform Console.
  2. Select the project you want to shut down, then click Delete project: this schedules the project for deletion.

What's next

Learn the whole platform

Now that you know what it's like to develop and deploy App Engine apps, you can stretch out and see the rest of Google Cloud Platform. You already have the Google Cloud SDK installed and that gives you the tools to interact with products like Google Cloud SQL, Google Cloud Storage, Google Cloud Datastore, and more. For a guided walkthrough that teaches you how to create an application that uses the entire platform, not just App Engine, check out our quickstart on creating the Bookshelf app.

Learn about the App Engine flexible environment

Here are some topics to help continue your learning about App Engine.

Hello World code review

Hello World is the simplest possible App Engine app, as it contains only one service, has only one version, and all of the code is located within the app's root directory. This section describes each of the app files in detail.

helloworld.go

The helloworld.go file registers a handler that listens for requests to /, and responds with the 'Hello world!' message.

package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/", handle)
	http.HandleFunc("/_ah/health", healthCheckHandler)
	log.Print("Listening on port 8080")
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func handle(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}
	fmt.Fprint(w, "Hello world!")
}

func healthCheckHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, "ok")
}

app.yaml

The app.yaml file describes an application's deployment configuration:

runtime: go
env: flex
Here, app.yaml specifies the runtime used by the app, and sets env: flex, specifying that the app uses the flexible environment.

  • For more information on how the Go runtime works, see The Go Runtime.

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App Engine flexible environment for Go