+++
date = "2020-03-17"
title = "Test Flutter on Drone CI"
tags = ["drone", "flutter", "ci"]
description = "This is a short post that shows how to use cirruslabs' flutter docker image to run your flutter tests on Drone CI."
+++

_This post is specific to [Drone CI][drone], but is probably easily adoptable to other CI systems, like Gitlab._

[Flutter][flutter] is UI library based on [Dart][dart] to create beautiful, natively compiled applications for mobile. Web and desktop targets are also in the works. 

Recently I've been playing around with Flutter and Dart. As a backend engineer I have to say I quite like it. Dart is a breeze to work with, the static typing helps a lot. Flutter itself offers a react-like way of structuring your app, but it runs natively on Android and iOS. At [Kabisa][kabisa] we're in the process of adopting Flutter as our go-to solution for cross platform mobile apps.

Anyway, one of the first things I do is hook a new project up with my CI, currently [Drone CI][drone]. I started looking for
an already published docker image that contains the latest flutter-stable installation. I soon found [cirruslabs/docker-images-flutter][cl-flutter],
but ran into an permission error. Turns out [I'm not the only one][cl-issues], but with a few simple steps you can test your flutter app with this image on Drone CI without issue.

`.drone.yml`:

```yaml
kind: pipeline
name: default

steps:
- name: test
  image: cirrusci/flutter:stable
  commands:
    - sudo chown -R cirrus:cirrus .
    - flutter doctor
    - flutter test
```

The magic is the `sudo chown -R cirrus:cirrus .`. The flutter docker images are based on Cirrus Labs' android SDK images, which runs
commands as the `cirrus` user. This will change permissions and the flutter commands can now run without issue. 

Any next steps in your pipeline will encounter files owned by `cirrus`. Since most drone plugins and images run as `root` anyway, this is not much of and issue. You could add another command to the snippet above to reset permissions back to `root`. 

Note that I'm using `cirrusci/flutter:stable`. They've also got images available for `beta` and `dev`, just use the appropriate tag.

[flutter]: https://flutter.dev/
[drone]: https://drone.io/
[dart]: https://dart.dev/
[cl-flutter]: https://github.com/cirruslabs/docker-images-flutter
[kabisa]: https://www.kabisa.nl