Homu

Homu is a bot that integrates with GitHub and your favorite continuous integration service, such as Buildbot or Travis CI.

Why is it needed?

Let's take Travis CI as an example. If you send a pull request to a repository, Travis CI instantly shows you the test result, which is great. However, after several other pull requests are merged into the master branch, your pull request can still break things after being merged into master. The traditional continuous integration solutions don't protect you from this.

In fact, that's why they provide the build status badges. If anything pushed to master is completely free from any breakage, those badges will not be necessary, as they will always be green. The badges themselves prove that there can still be some breakages, even when continuous integration services are used.

To solve this problem, the test procedure should be executed just before the merge, not just after the pull request is received. You can manually click the "restart build" button each time before you merge a pull request, but Homu can automate this process. It listens to the pull request comments, waiting for an approval comment from one of the configured reviewers. When the pull request is approved, Homu tests it using your favorite continuous integration service, and only when it passes all the tests, it is merged into master.

Note that Homu is not a replacement of Travis CI or Buildbot. It works on top of them. Homu itself doesn't have the ability to test pull requests.

Influences of bors

Homu is largely inspired by bors. The concept of "tests should be done just before the merge" came from bors. However, there are also some differences:

Stateful: Unlike bors, which intends to be stateless, Homu is stateful. It means that Homu does not need to retrieve all the information again and again from GitHub at every run. This is essential because of the GitHub's rate limiting. Once it downloads the initial state, the following changes are delivered with the Webhooks API.
Pushing over polling: Homu prefers pushing wherever possible. The pull requests from GitHub are retrieved using Webhooks, as stated above. The test results from Buildbot are pushed back to Homu with the HttpStatusPush feature. This approach improves the overall performance and the response time, because the bot is informed about the status changes immediately.

And also, Homu has more features, such as rollup, try, and the Travis CI support.

Usage

How to install

sudo apt-get install python3-venv

pyvenv .venv
. .venv/bin/activate

# Stable version

pip install homu

# Development version

git clone https://github.com/barosl/homu.git
pip install -e homu

How to configure

Copy cfg.sample.toml to cfg.toml, and edit it accordingly.
Create a GitHub account that will be used by Homu. You can also use an existing account. In the account settings, register a new application and generate a new access token (with the repo permission). The OAuth Callback URL should be http://HOST:PORT/callback, the homepage URL isn't needed and can be anything, for example http://HOST:PORT/.
Add a Webhook to your repository:

Payload URL: http://HOST:PORT/github
Content type: application/json
Secret: The same as repo.NAME.github.secret in cfg.toml
Events: Issue Comment, Pull Request, Push, Status

Add a Webhook to your continuous integration service:

Buildbot

Insert the following code to the master.cfg file:

from buildbot.status.status_push import HttpStatusPush

c['status'].append(HttpStatusPush(
    serverUrl='http://HOST:PORT/buildbot',
    extra_post_params={'secret': 'repo.NAME.buildbot.secret in cfg.toml'},
))

Travis CI

Add your Travis token as repo.NAME.travis.token in cfg.toml. Insert the following code to the .travis.yml file:
```
notifications:
    webhooks: http://HOST:PORT/travis

branches:
    only:
        - auto
```

How to run

. .venv/bin/activate

homu