Dart / Flutter - full stack demo for Cloud Run

This is a demo of a full stack application built with Dart and Flutter.

The frontend is a desktop Flutter app that sends a name that you enter to the backend and then displays the response (a greeting in various languages) in a snackbar (an ephemeral popup widget for displaying messages at the bottom of the page).

The backend is a Dart function app that was generated using the Functions Framework for Dart. It serves an HTTP endpoint that accepts a JSON-encoded request body and returns a JSON-encoded response body. For the demo, the function is hosted on localhost and on Cloud Run, a fully managed serverless platform on Google Cloud.

Build and deploy the backend

Change directory to backend.

cd backend

Local machine

You can run the function on your local machine by entering:

dart run build_runner build --delete-conflicting-outputs
dart run bin/server.dart --port=8080 --target=function

If you have make installed on your system, you can just enter:

make run

Output:

Listening on :8080

For more details see backend/README.

Cloud Run

If you have created a Google Cloud project and updated your local gcloud configuration with the project ID, you can deploy the backend in a single step.

For example, assuming your project ID is dart-demo and you want to deploy the function as a service called greeting, enter:

gcloud beta run deploy greeting --allow-unauthenticated --source=.

Output:

Building using Dockerfile and deploying container to Cloud Run service [greeting] in project [dart-demo] region [us-central1]
✓ Building and deploying new service... Done.
  ✓ Uploading sources...
  ✓ Building Container... Logs are available at [https://console.cloud.google.com/cloud-build/builds/df7f07d1-d88b-4443-a2b1-bdfd3cdab15b?project=700116488077].
  ✓ Creating Revision... Revision deployment finished. Waiting for health check to begin.
  ✓ Routing traffic...
  ✓ Setting IAM Policy...
Done.
Service [greeting] revision [greeting-00001-yen] has been deployed and is 
serving 
100 percent of traffic.
Service URL: https://greeting-gpua4upw6q-uc.a.run.app

The function app endpoint is the Service URL printed on the last line.

See Quickstart: Cloud Run for details on setting up and using a Google Cloud project.

Verify the backend works

If you have curl installed on your system, you can enter the following:

URL=http://localhost:8080  # or your Cloud Run service URL
curl -X POST -H "content-type: application/json" -d '{ "name": "World" }' -w "\n" $URL

Output (example):

{"salutation":"Hello","name":"World"}

Build and run the frontend

Change directory to frontend.

cd frontend

The following assumes running on the macos desktop.

Backend running on local machine

flutter run -d macos

flutter run -d macos -t lib/main_dev.dart

Backend running on Cloud Run

export GREETING_URL={Cloud Run service URL}
flutter run -d macos -t lib/main_prod.dart

grant/io21-dart-flutter-fullstack-demo