Jenkins pipeline read commit status from webhook - github

Question

I'm trying to find a way to have a Jenkins job be triggered by a PR comment matching a particular pattern, have the job check to see if the PR's latest commit status is PASSED, which would be set by a separate CI job that runs the moment the PR opens, and merge the code. The PR's comment would symbolize that the code has been properly peer reviewed, the commit status represents that all front and back end unit tests have already passed.
The only part of this that I'm really unsure about is retrieving the commit status from the webhook payload. Any advice?

Answer 1

TLDR
Call the statuses API to list all statuses created against that SHA or use the combined status API.
Finding the latest commit
If you don't have the SHA of the latest commit, then there are a few ways to get this from the API endpoints.
This will assume there is an application that listens for webhook events, specifically the IssuesCommentEvent, to parse the comment's body for the 'particular pattern'.
Get the URL to the Pull Request
A webhook event will contain the Pull Request url in the JSON body, e.g.:
{
"action": "created",
"issue": {
...
"pull_request": {
"url": "https://api.github.com/repos/sample/mysample/pulls/13",
...
}
}
}
}
Get the SHA or statuses endpoint
Use the pull request API endpoing url returned in the previous step. The JSON body will contain a statuses_url value, which will return each status created against that SHA or, or get the SHA and call any of the previously mentioned statuses endpoints.
{
"statuses_url": "https://api.github.com/repos/sample/mysamples/statuses/1985617647f17fe4fc85efeeaffef24581a12488",
...
"head":{
"sha": "1985617647f17fe4fc85efeeaffef24581a12488",
}
}