These tutorials target Micronaut Framework 3. Read, Guides for Micronaut Framework 4.

Table of Contents

Deploy to Google Cloud Run

Deploy a Micronaut application to Google Cloud Run - a fully managed serverless platform for containerized applications.

Authors: Sergio del Amo

Micronaut Version: 3.9.2

1. Getting Started

In this guide, we will create a Micronaut application written in Groovy.

You are going to deploy a Micronaut application to Google Cloud Run.

Develop and deploy highly scalable containerized applications on a fully managed serverless platform.

2. What you will need

To complete this guide, you will need the following:

3. Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

4. Writing the Application

Create an application using the Micronaut Command Line Interface or with Micronaut Launch.

mn create-app example.micronaut.micronautguide --build=gradle --lang=groovy
If you don’t specify the --build argument, Gradle is used as the build tool.
If you don’t specify the --lang argument, Java is used as the language.

The previous command creates a Micronaut application with the default package example.micronaut in a directory named micronautguide.

Setup IntelliJ IDEA to develop Micronaut Applications.

4.1. Controller

In order to create a microservice that responds with "Hello World" you first need a controller.

Create a Controller:

src/main/groovy/example/micronaut/HelloController.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import io.micronaut.http.annotation.Produces
import io.micronaut.http.MediaType

@CompileStatic
@Controller("/hello") (1)
class HelloController {
    @Get (2)
    @Produces(MediaType.TEXT_PLAIN) (3)
    String index() {
        "Hello World" (4)
    }
}
1 The class is defined as a controller with the @Controller annotation mapped to the path /hello.
2 The @Get annotation maps the index method to an HTTP GET request on /hello.
3 By default, a Micronaut response uses application/json as Content-Type. We are returning a String, not a JSON object, so we set it to text/plain.
4 A String "Hello World" is returned as the result

4.2. Test

Create a test to verify that when you make a GET request to /hello you get Hello World as a response:

src/test/groovy/example/micronaut/HelloControllerSpec.groovy
package example.micronaut

import io.micronaut.http.HttpRequest
import io.micronaut.http.client.HttpClient
import io.micronaut.http.client.annotation.Client
import io.micronaut.test.extensions.spock.annotation.MicronautTest
import spock.lang.Specification

import jakarta.inject.Inject

@MicronautTest (1)
class HelloControllerSpec extends Specification {

    @Inject
    @Client("/")  (2)
    HttpClient client

    void "test hello world response"() {
        when:
        HttpRequest request = HttpRequest.GET('/hello')  (3)
        String rsp = client.toBlocking().retrieve(request)

        then:
        rsp == "Hello World"
    }
}
1 Annotate the class with @MicronautTest so the Micronaut framework will initialize the application context and the embedded server. More info.
2 Inject the HttpClient bean and point it to the embedded server.
3 Creating HTTP Requests is easy thanks to the Micronaut framework fluid API.

5. Google Cloud Platform

Signup for the Google Cloud Platform

5.1. Cloud SDK

Install the Cloud SDK CLI for your operating system.

Cloud SDK includes the gcloud command-line tool. Run the init command in your terminal:

gcloud init

Log in to your Google Cloud Platform:

gcloud auth login

5.2. Google Cloud Platform Project

Create a new project with a unique name (replace xxxxxx with alphanumeric characters of your choice):

gcloud projects create micronaut-guides-xxxxxx
In GCP, project ids are globally unique, so the id you used above is the one you should use in the rest of this guide.

Change your project:

gcloud config set project micronaut-guides-xxxxxx

If you forget the project id, you can list all projects:

gcloud projects list

6. Docker Push

Push the Docker image of your application to Google Cloud Container Registry or to Google Cloud Artifact Registry.

Modify your Gradle build and configure the

...
..
.
dockerBuild {
    images = ["gcr.io/micronaut-guides-xxxxxx/micronautguide:latest"]
}
./gradlew dockerPush

The previous URL uses the pattern: gcr.io/micronaut-guides-xxxxxx/micronautguide:latest. Change it to use your Project ID.

You get an output such as:

....
..
.
Pushing image 'gcr.io/micronaut-guides-xxxxxx/micronautguide:latest'.

7. Google Cloud Run Deploy

You can deploy to Google Cloud Run via the CLI. Use the value you configured in your build as the image argument’s value.

gcloud run deploy \
    --image=gcr.io/micronaut-guides-xxxxxx/micronautguide:latest \
    --platform managed \
    --allow-unauthenticated

You will see an output such as:

Service name (micronautguide):
Please specify a region:

...

 [22] us-central1
 [23] us-east1
 [24] us-east4

...

 [29] cancel
Please enter your numeric choice:  23

To make this the default region, run `gcloud config set run/region us-east1`.

Deploying container to Cloud Run service [micronautguide] in project [micronaut-guides-xxxxxx] region [us-east1]
✓ Deploying... Done.
  ✓ Creating Revision...
  ✓ Routing traffic...
  ✓ Setting IAM Policy...
Done.
Service [micronautguide] revision [micronautguide-00002-fat] has been deployed and is serving 100 percent of traffic.
Service URL: https://micronautguide-63kwrzytgq-ue.a.run.app

8. Running the Application

curl -i https://micronautguide-li3tercjmq-ue.a.run.app/hello
HTTP/2 200
content-type: text/plain
x-cloud-trace-context: 139f91d74bfe5d24a2770fca9abef1d7
date: Sat, 02 Oct 2021 07:18:52 GMT
server: Google Frontend
content-length: 11
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000,h3-T051=":443"; ma=2592000,h3-Q050=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000,quic=":443"; ma=2592000; v="46,43"

Hello World

9. Next steps

You will probably want to deploy to Google Cloud Run from your CI server. Micronaut Launch contains feature github-workflow-google-cloud-run, which adds a GitHub Actions Workflow that deploys an application to Google Cloud Run from Google Container Registry.

Read more about:

10. Help with the Micronaut Framework

The Micronaut Foundation sponsored the creation of this Guide. A variety of consulting and support services are available.