This package provides support for running server applications written in Dart on Google App Engine using Custom Runtimes with Flex Environment.
This page assumes the Dart SDK (see
dart.dev/get-dart) as well as the Google
Cloud SDK (see cloud.google.com/sdk) were
installed and their bin folders have been added to PATH
.
To ensure gcloud was authorized to access the cloud project and we have the
app
component installed, we assume the following has been run:
$ gcloud auth login
$ gcloud auth application-default login
$ gcloud config set project <project-name>
$ gcloud components update app
Instead of running gcloud auth application-default login
it is also possible
to authenticate by making the environment variable
GOOGLE_APPLICATION_CREDENTIALS
point to a file containing
exported service account credentials.
To setup a hello world application we need 4 different things:
name: hello_world
version: 0.1.0
environment:
sdk: '>=2.0.0 <3.0.0'
dependencies:
appengine: ^0.12.0
runtime: custom
env: flex
service: default
FROM google/dart-runtime
### NOTE: Uncomment the following lines for local testing:
#ADD key.json /project/key.json
#ENV GOOGLE_APPLICATION_CREDENTIALS /project/key.json
#ENV GOOGLE_CLOUD_PROJECT dartlang-pub
This requires exported service account credentials in key.json
.
import 'dart:io';
import 'package:appengine/appengine.dart';
requestHandler(HttpRequest request) {
request.response
..write('Hello, world!')
..close();
}
main() async {
await runAppEngine(requestHandler);
}
There are two ways to run the application locally - with or without docker.
The simplest way to run the application is on the command line like this:
$ gcloud auth application-default login
$ export GOOGLE_CLOUD_PROJECT=<project-name>
$ dart bin/server.dart
This will serve the application at localhost:8080!
To be closer to the production environment one can run the application inside a docker container. In order to do so, docker needs to be installed first (see the official instructions.
In order to run the application locally we uncomment the 3 lines in the
Dockerfile
and place the service account key in key.json
:
ADD key.json /project/key.json
ENV GOOGLE_APPLICATION_CREDENTIALS /project/key.json
ENV GOOGLE_CLOUD_PROJECT dartlang-pub
We can then run the application via:
$ docker build .
...
Sucessfully built <docker-imgage-hash>
$ docker run -it <docker-imgage-hash>
...
In order to find out at which IP the Docker container is available we inspect the running container via:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
<container-id> ...
app % docker inspect --format '{{ .NetworkSettings.IPAddress }}' <container-id>
172.17.0.2
Then the application will be available at 172.17.0.2:8080.
Before deploying the app, be sure to remove the environment variables in the
Dockerfile
which we used for local testing!
To deploy the application to the cloud we run the following command (optionally
passing the --no-promote
flag to avoid replacing the production version)
$ gcloud app deploy --no-promote app.yaml
...
Updating service [default]...done.
Deployed service [default] to [https://<version-id>-dot-<project-id>.appspot.com]
...
This will perform a remote docker build in the cloud and deploy a new version.
You can find the URL to the version that got deployed
in the output of gcloud app deploy
(as well as via the
Cloud Console under AppEngine > Versions
).