Web hooks - merge request and update commits


I’m currently interested if there is a web hook that would send out data if I push a new commit under a branch for which the merge request is opened.

I have a Sinatra app that handles the JSON data, parses it and then contacts Jenkins to start a build process for the project.

So far, what I’ve tested, if I only use “Merge Request Events” I get them only when the Merge request is opened or merged, if I push a commit in a opened Merge Request there is no data sent to the Sinatra app.

Furthermore, if the “Push events” is enabled, then I can’t really distinguish if the Merge Request for that branch was opened or not, it would just contact the Sinatra app, which would start a build process.

I’m migrating from Bitbucket where they had the actions defined as “pullrequest_created”, “pullrequest_updated”, “pullrequest_merged” - I’m wondering if there is the same thing possible with Gitlab ?

Thank you!