This directory exists to support building Flutter on our build infrastructure.

The results of such builds are viewable at https://build.chromium.org/p/client.flutter/waterfall

The external master pages do not allow forcing new builds. Contact @eseidelGoogle or another member of Google's Flutter team if you need to do that.

Our infrastructure is broken into two parts. A buildbot master specified by our builders.pyl file, and a set of recipes which we run on that master. Both of these technologies are highly specific to Google's Chromium project. We're just borrowing some of their infrastructure.

• install depot_tools
• Python package installer: sudo apt-get install python-pip
• Python coverage package (only needed for training_simulation): sudo pip install coverage

The following will get way more than just recipe code, but it will get the recipe code:

mkdir chrome_infra
cd chrome_infra
fetch infra

More detailed instructions can be found here.

Most of the functionality for recipes comes from recipe_modules, which are unfortunately spread to many separate repositories. After checking out the code search for files named api.py or example.py under infra/build.

Flutter has one recipe per repository. Currently flutter/flutter and flutter/engine:

• build/scripts/slave/recipes/flutter/flutter.py
• build/scripts/slave/recipes/flutter/engine.py

Recipes are just Python. They are documented by the luci/recipes-py github project.

The typical cycle for editing a recipe is:

1. Make your edits (probably to files in //chrome_infra/build/scripts/slave/recipes/flutter).
2. Run build/scripts/slave/recipes.py simulation_test train flutter to update expected files (remove the flutter if you need to do a global update).
3. Run build/scripts/tools/run_recipe.py flutter/flutter (or flutter/engine) if something was strange during training and you need to run it locally.
4. Upload the patch (git commit, git cl upload) and send it to someone in the recipes/flutter/OWNERS file for review.

Flutter uses Chromium's fancy builders.pyl master generation system. Chromium hosts 100s (if not 1000s) of buildbot masters and thus has lots of infrastructure for turning them up and down. Eventually all of buildbot is planned to be replaced by other infrastructure, but for now flutter has its own client.flutter master.

You would need to edit client.flutter's master in order to add slaves (talk to @eseidelGoogle), add builder groups, or to change the html layout of https://build.chromium.org/p/client.flutter. Carefully follow the builders.pyl docs to do so.

We would like to host our own recipes instead of storing them in build. Support for cross-repository recipes is in-progress. If you view the git log of this directory, you'll see we initially tried, but it's not quite ready.