Deploy a Java app to Google Cloud App Engine auto by create git tag using GitHub Action

First, we need to create a Java base web application. We create a new application by using Quarkus.

How to install quarkus command

quarkus create app medium-demo-app

-----------

applying codestarts...
📚  java
🔨  maven
📦  quarkus
📝  config-properties
🔧  dockerfiles
🔧  maven-wrapper
🚀  resteasy-reactive-codestart

-----------
[SUCCESS] ✅  quarkus project has been successfully generated in:
--> /medium-demo-app
-----------

Next, open the medium-demo-app project, add a new class named “TopResource” and add the following code.

package org.acme;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/")
public class TopResource {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Hello, this is a demo website for medium story.";
    }
}

And then, add the following code to application.properties file.

quarkus.package.type=uber-jar

Now, compile and access the page.

quarkus dev

After compile finished, open a browser and access http://localhost:8080 , then we should see the page just look like bellow.

Top Page of the demo app

Next, create a new GCP project, and create app engine application.

Create App Engine Application

Select a Region

Next, enable the App Engine Admin API and IAM API.

API Dashboard

Enable IAM API

Next, create a service account to deploy application. Go to the Service Accounts Page, and create a new service account.

Create a New Service Account

Then add roles to the account.

Add Roles

The following role are needed.

• App Engine Admin
• Service Account User
• Storage Admin
• Cloud Build Editor

After create the service account, click the account’s email, select key tab to create a new key. Select the key type to JSON. Then it will download a JSON file.

Download a JSON File

Next, go to GitHub to create a new repository. And add the Quarkus app we created before to the repository and push to the remote.

After that, we need to create a new folder under project root named “.github/workflows”, then create new file named “google-deploy-app-engine-source.yml”.

In the yml file, we want to deploy after a tag is created, so we add the code below first. This means after we push a new tag to the remote which tag name like “v1.0.0” or any other tag name start with a “v”, it will run the jobs.

name: Deploy to App Engine from Source

on:
  push:
    tags:
      - 'v*'

Next, we will define the jobs. First, we need to authorized the deploy account’s information. Create a new repository secret value named “GCP_SA_KEY”, and put the contents of the JSON file we download before into the secret, then add the code bellow to the yaml file.

jobs:
  job_id:
    permissions:
      contents: 'read'
      id-token: 'write'

    runs-on: ubuntu-latest
    steps:
      - uses: 'actions/checkout@v3'

      - id: 'auth'
        name: 'Authenticate to Google Cloud'
        uses: 'google-github-actions/auth@v1'
        with:
          credentials_json: '${{ secrets.GCP_SA_KEY }}'

Because we will use gcloud command to deploy, so we need to setup gcloud command next.

      - name: 'Set up Cloud SDK'
        uses: 'google-github-actions/setup-gcloud@v1'

Then build the Java application.

      - name: Set up JDK 17
        uses: actions/setup-java@v3
        with:
          java-version: '17'
          distribution: 'temurin'
          cache: maven

      - name: Build App
        run: mvn clean package

And at last, deploy the app to the App Engine.

      - name: Deploy to App Engine
        id: deploy
        run: gcloud app deploy ${{ github.workspace }}/target/medium-demo-app-1.0.0-SNAPSHOT-runner.jar

The whole yaml file is below.

name: Deploy to App Engine from Source

on:
  push:
    tags:
      - 'v*'

jobs:
  job_id:
    permissions:
      contents: 'read'
      id-token: 'write'

    runs-on: ubuntu-latest
    steps:
      - uses: 'actions/checkout@v3'

      - id: 'auth'
        name: 'Authenticate to Google Cloud'
        uses: 'google-github-actions/auth@v1'
        with:
          credentials_json: '${{ secrets.GCP_SA_KEY }}'

      - name: 'Set up Cloud SDK'
        uses: 'google-github-actions/setup-gcloud@v1'

      - name: Set up JDK 17
        uses: actions/setup-java@v3
        with:
          java-version: '17'
          distribution: 'temurin'
          cache: maven

      - name: Build App
        run: mvn clean package

      - name: Deploy to App Engine
        id: deploy
        run: gcloud app deploy ${{ github.workspace }}/target/medium-demo-app-1.0.0-SNAPSHOT-runner.jar

At last, create a new release tag on github to see the weather the GitHub action is working correct or not.

Deployed WebSite