Flutter Bitbucket Pipeline cache

It was pretty tricky to speed up the pipeline since there are not so many resources on how to cache your flutter app on Bitbucket Pipeline.

Read how to setup bitbucket pipelines for flutter if you just want to get started.

How Dart/Flutter saves dependencies#

Whenever you run flutter pub get, the system downloads all dependencies to the folder .pub-cache in your home directory. The Folder contains all cached dependencies and will look similar to:

.pub-cache/hosted/pub.dartlang.org/linkfive_purchases-2.0.2/

Caching those dependencies makes sense since a plugin with a specific version will never change. It's basically not possible to upload the same version with a different code to pub.dev.

Dependency version changes#

Whenever you change your dependencies, the new versions will appear in the same Folder.

.pub-cache/hosted/pub.dartlang.org/linkfive_purchases-2.0.1/ .pub-cache/hosted/pub.dartlang.org/linkfive_purchases-2.0.2/

Alright. Let's cache the dependencies with bitbucket pipelines

bitbucket-pipelines.yml config definitions#

We want all dependencies to be cached in the .pub-cache folder on bitbucket.

For this we define certain definitions that can be referenced in future steps.

definitions:
  steps:
    - step: &Flutter-pub-get
        name: Flutter Pub Get
        script:
          - flutter pub get
        artifacts:
          - .dart_tool/**
          - .flutter-plugins
          - .flutter-plugins-dependencies
          - build/**
        caches:
          - dartpubcache
    - step: &Lint-and-test
        name: Flutter lint and test
        caches:
          - dartpubcache
        script:
          - flutter analyze
          - flutter test ./test
  caches:
    dartpubcache: $HOME/.pub-cache

We define the steps Flutter-pub-get and Lint-and-test plus the cache directory $HOME/.pub-cache

Now we just need to use the steps in any pipeline runner.

pipelines:
  pull-requests:
    '**':
      - step: *Flutter-pub-get
      - step: *Lint-and-test
      - step:
          name: Build Flutter Android appbundle 
          deployment: production
          caches:
            - dartpubcache
          script:
            - flutter build appbundle

and Bitbucket also notes that the cache was downloaded

Cache "dartpubcache": Downloading
Cache "dartpubcache": Downloaded 40.6 MiB in 2 seconds
Cache "dartpubcache": Extracting
Cache "dartpubcache": Extracted in 1 seconds

Cache duration#

The bitbucket cache will refreshed after a week. You can also delete the cache manually inside the bitbucket pipeline section. Click on the top right Cache button.

Flutter dependency update#

It also does not cause any problems if you change your dependencies before the cache has expired. The only thing that happens is that the command flutter pub get takes a little longer because additional dependencies are downloaded.

Best, Alex