Create endpoint for Github Webhooks

[tallysmartins]

Create the endpoint to listen to activities of registered repos and trigger Job runs according to new commits in branches and pull requests.

• 1. Investigate how github send hook payloads and what events we want to listen

• 2. Investigate how to guarantee security and certify hook requests came from the right source

• 3. Initial implementation for a single event

• 4. Implementation for all the other events

• 5. Implement auth verification (secret and hash stuff)

[tallysmartins]

@PragTob @michalmuskala I created this issue to point some considerations regarding this task

Subtask 1: I found in the webhook events docs that two events seems to be the ones that we need the push and pull_requests We can start with any of them. Github requests come with a X-GitHub-Event that says the type of the event, aka push, pull_request, comment and the action associated, opened, edited, closed, etc.

Subtask 2: Its possible to set up a secret key that is used to hash the request body with HMAC-sha1 that is sent in the header as X-Hub-Signature.

Subtask 3: I created a new controller and started implementation of pull_request using the payload from the docs and without much verification. But I would like to discuss some points before continue on this:

• 1 If a Job exists for a given branch and commit, do not trigger another one, right?
• 2 If a Job is triggered from a PR I see two options: The first is to find the PR reference in the base repository and trigger a Job associated with it. The second is just create a new repository object related to the source repo and trigger a job associated with it. The first one makes more sense for me but any of them can be the solution.