The Flutter autosubmit bot is a tool that helps developers submit changes to the Flutter codebase. It automates the process of validating pull requests, test validation, and merging changes. This frees up developers to focus on writing code, and makes it easier to contribute to the Flutter project.
When a developer opens a pull request against any of the currently supported repositories, the cocoon backend will schedule tests and checks against that pull request. Rather than have the developer wait around to make sure all these tests and validations have completed, they can add a label and the Autosubmit bot will then queue that pull request for merge upon successfully passing all checks and validations. It will look something like this:
autosubmit label to notify the Autosubmit bot that you would like it to merge the pull request upon successful validation.The following are the rules for code reviews:
flutter-hackers org then they will need at least 1 other review from a member of the flutter-hackers org, preferable a code owner from that repository.flutter-hackers org then they will need at least 2 other reviews from members of the flutter-hackers org.autosubmit label will be removed until the reviewer who requested changes has approved the pull request.When a pull request is opened the Cocoon backend service will create a number of test runs that will be used to validate the code change that was submitted. Once the autosubmit label is added, the Autosubmit bot will check the statuses of those tests and will not merge the pull request until all of them have succeeded. If the any of the tests have failed the autosubmit label will be removed and the bot will no longer process that pull request. However the developer can re-trigger the test and add the label again to retry.
The Autosubmit bot will make several other checks to determine viability of the pull request up until the moment the pull request is queued for merge. They are:
Autosubmit can also undo a change automatically simply by adding a label and a comment to a pull request. By adding the label ‘revert’ to a closed pull request the autosubmit bot will know to create a new request to revert this change and provide the specified reason in the body of the resulting revert request.
If an empty reason is supplied then the ‘revert’ label will be removed and a comment supplied that you must supply a reason.
The Autosubmit bot is a service hosted within GCP that listens to GitHub's webhook events utilizing PubSub to store the messages it is interested in for further processing. A cron job calls the service every two minutes to look for new events from GitHub to see if any new pull requests need to be processed.
If an event contains a new pull request we look at it for the ‘autosubmit’ label. If the pull request is valid, i.e. it came from GitHub then we send it in a message to our PubSub topic.
A cron job will then call the Autosubmit service which will pull messages from the topic for processing and validation. If the pull request has passed the validations outlined above then the it will be merged and the PubSub message acknowledged. Autosubmit will no longer process that pull request.
{TODO add a diagram of the components}
The Autosubmit bot gets its configuration from a configuration file in the Orgs .github repository, specifically at .github/autosubmit/autosubmit.yml. These configurations govern the validations that the Autosubmit will perform and can be updated on the fly. These configs can also be overridden in other repositories so that the configuration can be tuned according to the repositories code owners liking.
| Config Name | Optional | Type | Default Value | Explanation |
|---|---|---|---|---|
default_branch | Yes | String | ‘main’ | the default branch of the repository where pull requests are merged into. This can be provided in the configuration but if it is not, the bot will collect this from a call to the Github API. |
allow_config_override | Yes | boolean | false | flag to allow specific repositories to override the values defined at the Org level for Autosubmit. See below. |
auto_approval_accounts | Yes | Array of String | [ ] | the accounts that can submit pull requests automatically with automatic review approval. The values here should be reserved for trusted entities such as dependabot or org created accounts. |
approving_reviews | Yes | integer | 2 | Integer, the number of reviews required before Auto-submit will merge a pull request upon approval. |
approval_group | No | String | the group a pull request author must get approval from in order to merge their pull request into the repository. See the rules on Approvals above. | |
run_ci_checks | Yes | boolean | true | a flag to determine whether or not to run target checks from ci.yaml or not. Not all repositories may want to do this initially. It is strongly recommended that this be set to True always. |
support_no_review_revert | Yes | boolean | true | flag to toggle condition of reviews required on revert requests. Flutter does not require an initial review but other repos may not want this. |
required_checkruns_on_revert | Yes | Array of String | [ ] | a list of check runs that Auto-submit will require to complete before merging a revert pull request regardless of what support_no_review_revert is set to. |
Here is an example of a full Autosubmit bot configuration file:
default_branch: main allow_config_override: false auto_approval_accounts: - skia-flutter-autoroll - engine-flutter-autoroll - dependabot[bot] - dependabot - DartDevtoolWorkflowBot approving_reviews: 2 approval_group: flutter-hackers run_ci: true support_no_review_revert: true required_checkruns_on_revert: - ci.yaml validation
An example of the minimum configuration file
approval_group: flutter-hackers
All repositories within an Org need not follow the same rules. Some may want more Approvals for a review, some may not want to allow Reverts without a review. Autosubmit allows this by allowing an override configuration file to be defined in the repositories .github directory. This is different than the Org .github repository.
In order to override the configuration at the Org level, the allow_config_override flag must be set to true. This tells Autosubmit that it will need to look in the local repositories .github directory for an autosubmit.yml file. Specifically that file will need to be places here: <repo>/.github/autosubmit/autosubmit.yml.
The following rules will apply to override values:
An example of Config Override:
The Org level config is defined as follows:
allow_config_override: true auto_approval_accounts: - skia-flutter-autoroll - engine-flutter-autoroll approving_reviews: 2 approval_group: flutter-hackers run_ci: true support_no_review_revert: true required_checkruns_on_revert: - ci.yaml validation
At the repository level the team would like to add a few more accounts to the auto_approval_accounts for automation purposes and required 1 more review but also would like revert requests to require reviews. So the repository level config would define the new values as follows:
auto_approval_accounts: - dependabot[bot] - dependabot - DartDevtoolWorkflowBot approving_reviews: 3 support_no_review_revert: false
The final merged configuration for the repository would then become:
auto_approval_accounts: - skia-flutter-autoroll - engine-flutter-autoroll - dependabot[bot] - dependabot - DartDevtoolWorkflowBot approving_reviews: 3 approval_group: flutter-hackers run_ci: true support_no_review_revert: false required_checkruns_on_revert: - ci.yaml validation
The code for the Autosubmit bot is part of the flutter infra tools and can be found here: https://github.com/flutter/cocoon
Currently the bot is not available from the Github marketplace so it is only available to support internal Google Repositories. In order to install the App you will need to:
After the app is installed you will need to place a configuration file into your ORGs .github repository. If you do not have one then you will need to create onc in your ORG level .github repository.
Once the repository is created then you will need to add the Autosubmit configuration file at .github/autosubmit/autosubmit.yml. This is the primary location that Autosubmit will check first for the configuration. Repositories in your ORG can override the ORG level configs by placing a configuration file at repo/.github/autosubmit/autosubmit.yml. See the section on configuration above on the fields you may want to include in your configuration.
Make sure that the App has read write access to the ORG level .github repository.
In order for the Autosubmit bot to merge pull requests it will need write access on the repository and it will need to be added to the branch protection section on who can push to the repository.
An ‘autosubmit’ label will also need to be created for the supported repository. You can visit this page to view instructions on creating the label.
Once the Autosubmit app has been installed in the repository, the configuration has been added and the target repository has been configured for write access you are ready to utilize the Autosubmit bot. In order to use the Autosubmit on pull requests in the target repository, follow these steps: