Enable Webhooks for Pull Requests

[mwerner]

This PR will add functionality to the github webhook. It expands the types of webhook types Samson will respond to beyond Code Push. It uses the ChangeSet namespace to establish a common protocol to be a webhook handler. The GithubController then delegates the method calls to the webhook handler, and uses the returned info to decide how to respond.

1. Adding a "Any Pull Request" webhook will start watching webhooks for pull requests, and the issue comments present on those pull requests.
2. I have hardcoded the requirement of [samson] to be present in the body of either the Pull Request or Issue Comment.
3. If the base for the pull request is production Samson will ignore the [samson] requirement.

@zendesk/samson

[grosser]

can you elaborate on what this will be used for / what this enabled or fixes ?

[mwerner]

The intent is to be able to build and upload assets on Pull requests that are deemed by those involved as something worth testing. Currently they need to copy their sha to Samson. I am aiming to expedite that process by watching for an explicit [samson] reference.

[grosser]

how about /\[\s*samson\s*\]/i ?

[grosser]

so when I push multiple times, this will run multiple times ?

sounds like a useful feature ...

[mwerner]

This is separate from the code push webhook.

In a hypothetical example:
You can open a PR with [samson] in the body of the PR description and have your webhook run. Push a few commits and discuss various parts of the code without triggering any webhooks. Then write an issue comment with [samson] in it and fire your webhook with the latest sha on the PR.

[mwerner]

I noticed some behavior that was slightly different than I expected, but I think I'm in favor of. If you put [samson] in your PR description, every subsequent code push will cause a pull request sync webhook which will pass the [samson] in the PR body test, causing a deploy.

If you only include [samson] in a comment, it will trigger a webhook once for the latest sha on that pull request, but subsequent code pushes will not cause anything.

This could be useful for developers that want to cause all code pushes on a PR to be deployed using [samson] in the PR description or simply deploy once using a PR comment with [samson]

I'm open to either way, but as it stands I left the behavior as is described here.

[mwerner]

Was discussing the usage of [samson]. Should we use something that prevents us from accidentally hitting the webhook on a markdown comment mentioning samson?

[steved]

charon does (^|\s)\[charon review\]($|\s) as the regex match

[steved]

wfm 👍

[steved]

Where does this come from?

[mwerner]

Leftover from when the changeset_from_webhook was making a github api call. thanks.

[mwerner]

Decided to follow Charon's pattern using [samson review] I didn't want to use "deploy" or "publish" since those are project specific terms. I'm good with "review" and this will keep things consistent.