DevOps #

Commands #

There are a bunch of flutter commands that are useful for creating pipelines. Here is a quick overview.

Testing #

See Testing Flutter apps for an overview of the different kinds of testing.

Running specific tests #

Just running flutter test will execute tests in the test folder. You can append a path to only run specific tests. Example:

flutter test test/widget_test.dart

Coverage #

You can get a code coverage report for the tests with:

flutter test --coverage

It will generate a coverage report in lcov format. You will find the output at coverage/lcov.info. It looks like this:

SF:lib/main.dart
DA:1,1
DA:2,1
LF:2
LH:2
end_of_record

Not very human friendly. You can turn it into HTML with:

genhtml ./coverage/lcov.info -o ./coverage/html

You will find the index at coverage/html/index.html and it looks like this:

The genhtml command is part of the aforementioned lcov package. So it needs to be available. How you do that, depends on the OS.

Windows

In git-bash:

Download https://github.com/jgonzalezdr/lcov/releases/download/v1.15.alpha1w/lcov-1.15.alpha1w.zip

Extract to C:\Users\<your username>\lcov

Then you can do:

~/lcov/genhtml ./coverage/lcov.info -o ./coverage/html

macOS

brew install lcov

Assuming you have Homebrew installed.

Debian/Ubuntu

apt install lcov

Integration test #

Integration test in the Flutter world, means that you run tests on a real (or emulated) device.

What you need to do, depends a bit on the platform.

Web #

Before executing tests you need ChromeDriver downloaded and running. See here.

Mobile #

I don’t have a good solution here.

You could try Firebase Test Lab. But, free quota is pretty low.

See pricing for Test Lab.

Build/Release #

Web #

Just run flutter build web then upload files in build/web to a static web host.

You can find instructions on deployment to Firebase hosting here.

You can get a token, that can be used to deploy from CI/CD with:

firebase login:ci

Configure the token as an environment variable named FIREBASE_TOKEN in your CI/CD pipeline. Then deploy from your pipeline with:

firebase deploy --token "$FIREBASE_TOKEN"

Links:

• Build and release a web app
• Continuous delivery with Flutter

iOS #

It’s complicated

Android #

Android uses a package format called APK. You can simply bundle your app to an APK then copy it to a Android device and install it.

flutter build apk

Then upload build/app/outputs/flutter-apk/app-release.apk to somewhere.

You can make the bundle size smaller by building individual APKs per hardware platform.

flutter build apk --split-per-abi

Here is the size difference for a basic app.

Note: most newer phones are running 64 bit ARM, so they will use the app-arm64-v8a-release.apk.

APKs needs to be digitally signed before they can be put on Play Store. I think that is out of scope.

Monitoring #

Monitoring is important to detect defects early, optimize performance and gain insight for improving user experience.

Google got two great services under the Firebase umbrella. Check out the links:

• Get started with Google Analytics
• Firebase Crashlytics

Drone CI #

Here is a minimal pipeline that test and build a Flutter project.

kind: pipeline
type: docker
name: default

steps:
  - name: test
    image: instrumentisto/flutter:3.19
    commands:
      - flutter doctor
      - flutter pub get
      - flutter test
  - name: build
    image: instrumentisto/flutter:3.19
    commands:
      - flutter pub get
      - flutter build apk

I couldn’t find an official Flutter image. However, instrumentisto/flutter seems like an okay option. It is based on Ubuntu 22.04, got Android SDK and latest version of Flutter build in. Not the most minimal image though.