This is a Java application built on the Spring framework, used to demonstrate an "infrastructure-as-code" deployment to Google Cloud Platform.
The application connects to a Google Cloud Spanner instance to retrieve the latest message in a database, and displays the message on a web page. API endpoints to list messages and set new messages are also available.
Spring Boot application properties are retrieved from
A live deployment of the application requires you to have a Google Cloud Platform account with billing enabled. However, the application can be run in a "local" mode, where the application will connect to a Google Cloud Spanner emulator and no Google Cloud Platform credentials need to be configured.
The application is intended to be deployed using the Terraform configuration here.
- Java 17 (JRE)
Get the code:
git clone https://github.com/zsrv/gcp-hello-world.git
cd gcp-hello-worldThe steps listed here will run the emulator on your local machine using the gcloud CLI. Other ways to run the emulator are described in the Cloud Spanner documentation.
This quick start guide requires the gcloud CLI to be installed. If the gcloud CLI is not installed, see the documentation above for details.
Start the emulator:
gcloud emulators spanner startIn a separate terminal, create a separate gcloud configuration for this application's local deployment:
gcloud config configurations create gcp-hello-world-emulator
gcloud config set auth/disable_credentials true
gcloud config set project gcp-hello-world-local
gcloud config set api_endpoint_overrides/spanner http://localhost:9020/Create a Spanner instance, a database on the instance, and the required table on the database:
gcloud spanner instances create gcp-hello-world --config=emulator-config \
--nodes=1 --description="Local Instance" \
--configuration=gcp-hello-world-emulator
gcloud spanner databases create main --instance=gcp-hello-world \
--configuration=gcp-hello-world-emulator
gcloud spanner databases ddl update main --instance=gcp-hello-world --ddl="$(<schema.ddl)" \
--configuration=gcp-hello-world-emulatorThe Spanner emulator is now ready to be used by the application.
The Maven Wrapper is included in the project as a convenient way to use Maven without having to first install it.
Build the application, specifying the local profile (used when the tests are run). The Cloud Spanner emulator must be running during the package phase since a connection to Cloud Spanner will be attempted during the test phase. Alternatively, the tests can be skipped.
./mvnw clean package -Dspring.cloud.bootstrap.name=bootstrap-local
# Alternatively, skip the tests so packaging doesn't fail if the Cloud Spanner emulator is not running
./mvnw clean package -DskipTestsRun the application, making sure to adjust the name of the jar if the version number has changed. The application will listen on localhost:8080 by default:
java -jar target/gcp-hello-world-0.0.1-SNAPSHOT.jar --spring.cloud.bootstrap.name="bootstrap-local"The application will listen on http://localhost:8080 by default, when running in local mode.
The main web page will display the most recent message in the database, along with the message ID and the time the message was added to the database. If there are no messages, or an error occurred, an error page will display instead.
Messages can be added to the database using the API endpoints.
Returns all messages in the database.
curl -w '\n' -i -X GET http://localhost:8080/api/v1/messagesOne message exists:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages
HTTP/1.1 200
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:12:14 GMT
[{"messageId":"365995c7-c327-4fcb-af07-30bd542e9b5c","message":"Hello World","creationTimestamp":"2022-06-06T11:05:59.491305932"}]
More than one message exists:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages
HTTP/1.1 200
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:17:03 GMT
[{"messageId":"365995c7-c327-4fcb-af07-30bd542e9b5c","message":"Hello World","creationTimestamp":"2022-06-06T11:05:59.491305932"},{"messageId":"5913dbf2-dc1f-4cf8-858c-7bba324dfece","message":"Hello World Two","creationTimestamp":"2022-06-06T11:16:55.470348823"}]
No messages exist:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages
HTTP/1.1 200
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:04:30 GMT
[]
Returns the message with the given id.
curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/c51c38f0-9e5c-404f-abce-edd18280dbe5Message with given id exists:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/365995c7-c327-4fcb-af07-30bd542e9b5c
HTTP/1.1 200
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:09:36 GMT
{"messageId":"365995c7-c327-4fcb-af07-30bd542e9b5c","message":"Hello World","creationTimestamp":"2022-06-06T11:05:59.491305932"}
Message with given id does not exist:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/c51c38f0-9e5c-404f-abce-edd18280dbe5
HTTP/1.1 404
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:06:46 GMT
{"timestamp":"2022-06-06T11:06:46.242+00:00","status":404,"error":"Not Found","path":"/api/v1/messages/c51c38f0-9e5c-404f-abce-edd18280dbe5"}
Returns the message most recently added to the database.
curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/latestAt least one message exists:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/latest
HTTP/1.1 200
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:13:03 GMT
{"messageId":"365995c7-c327-4fcb-af07-30bd542e9b5c","message":"Hello World","creationTimestamp":"2022-06-06T11:05:59.491305932"}
No messages exist:
$ curl -w '\n' -i -X GET http://localhost:8080/api/v1/messages/latest
HTTP/1.1 404
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 06 Jun 2022 11:19:02 GMT
{"timestamp":"2022-06-06T11:19:02.698+00:00","status":404,"error":"Not Found","path":"/api/v1/messages/latest"}
Adds a new message to the database. Returns the message id of the new message on success.
curl -w '\n' -i -X POST -H "Content-Type: application/json" -d '{"message": "Hello World"}' http://localhost:8080/api/v1/messages$ curl -w '\n' -i -X POST -H "Content-Type: application/json" -d '{"message": "Hello World"}' http://localhost:8080/api/v1/messages
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 36
Date: Mon, 06 Jun 2022 11:05:59 GMT
365995c7-c327-4fcb-af07-30bd542e9b5c
Most recent message displayed on the home page:
Error message displayed when there are no messages:
