Read json payload from gitlab webhook in Jenkins

Question

I followed this tutorial to setup a Jenkins job to run whenever a push is made to the gitlab repository. I tested the webhook and I can see that the job is triggered. However, I don't see anything in the payload.

Just wondering, if anyone has ever tried to read the payload received from gitlab webhook?

Answer 1

Jenkins Gitlab Plugin sends these POST parameters to Jenkins whenever any event occurs in the Gitlab repo.

You can add env in the Jenkins console to get what all Gitlab parameters are exported to the Jenkins environment. Then you can print or use the required variables.

eg

echo $gitlabSourceRepoURL
echo $gitlabAfter
echo $gitlabTargetBranch
echo $gitlabSourceRepoHttpUrl
echo $gitlabMergeRequestLastCommit
echo $gitlabSourceRepoSshUrl
echo $gitlabSourceRepoHomepage
echo $gitlabBranch
echo $gitlabSourceBranch
echo $gitlabUserEmail
echo $gitlabBefore
echo $gitlabSourceRepoName
echo $gitlabSourceNamespace
echo $gitlabUserName

Answer 2

The tutorial you have mentioned talks about GitHub webhooks. GitLab and GitHub are two separate products. So, the documentation or links for GitHub webhooks will not apply to GitLab webhooks.

GitLab invokes the webhook URL with a JSON payload in the request body that carries a lot of information about the GitLab event that led to the webhook invocation. For example, the GitLab webhook push event payload carries the following information in it:

{
  "object_kind": "push",
  "before": "95790bf891e76fee5e1747ab589903a6a1f80f22",
  "after": "da1560886d4f094c3e6c9ef40349f7d38b5d27d7",
  "ref": "refs/heads/master",
  "checkout_sha": "da1560886d4f094c3e6c9ef40349f7d38b5d27d7",
  "user_id": 4,
  "user_name": "John Smith",
  "user_username": "jsmith",
  "user_email": "john@example.com",
  "user_avatar": "https://s.gravatar.com/avatar/d4c74594d841139328695756648b6bd6?s=8://s.gravatar.com/avatar/d4c74594d841139328695756648b6bd6?s=80",
  "project_id": 15,
  "project":{
    "id": 15,
    "name":"Diaspora",
    "description":"",
    "web_url":"http://example.com/mike/diaspora",
    "avatar_url":null,
    "git_ssh_url":"git@example.com:mike/diaspora.git",
    "git_http_url":"http://example.com/mike/diaspora.git",
    "namespace":"Mike",
    "visibility_level":0,
    "path_with_namespace":"mike/diaspora",
    "default_branch":"master",
    "homepage":"http://example.com/mike/diaspora",
    "url":"git@example.com:mike/diaspora.git",
    "ssh_url":"git@example.com:mike/diaspora.git",
    "http_url":"http://example.com/mike/diaspora.git"
  },
  "repository":{
    "name": "Diaspora",
    "url": "git@example.com:mike/diaspora.git",
    "description": "",
    "homepage": "http://example.com/mike/diaspora",
    "git_http_url":"http://example.com/mike/diaspora.git",
    "git_ssh_url":"git@example.com:mike/diaspora.git",
    "visibility_level":0
  },
  "commits": [
    {
      "id": "b6568db1bc1dcd7f8b4d5a946b0b91f9dacd7327",
      "message": "Update Catalan translation to e38cb41.",
      "timestamp": "2011-12-12T14:27:31+02:00",
      "url": "http://example.com/mike/diaspora/commit/b6568db1bc1dcd7f8b4d5a946b0b91f9dacd7327",
      "author": {
        "name": "Jordi Mallach",
        "email": "jordi@softcatala.org"
      },
      "added": ["CHANGELOG"],
      "modified": ["app/controller/application.rb"],
      "removed": []
    },
    {
      "id": "da1560886d4f094c3e6c9ef40349f7d38b5d27d7",
      "message": "fixed readme",
      "timestamp": "2012-01-03T23:36:29+02:00",
      "url": "http://example.com/mike/diaspora/commit/da1560886d4f094c3e6c9ef40349f7d38b5d27d7",
      "author": {
        "name": "GitLab dev user",
        "email": "gitlabdev@dv6700.(none)"
      },
      "added": ["CHANGELOG"],
      "modified": ["app/controller/application.rb"],
      "removed": []
    }
  ],
  "total_commits_count": 4
}

The Jenkins GitLab plugin makes this webhook payload information available in the Jenkins Global Variable env . The available env variables are as follows:

gitlabBranch
gitlabSourceBranch
gitlabActionType
gitlabUserName
gitlabUserEmail
gitlabSourceRepoHomepage
gitlabSourceRepoName
gitlabSourceNamespace
gitlabSourceRepoURL
gitlabSourceRepoSshUrl
gitlabSourceRepoHttpUrl
gitlabMergeRequestTitle
gitlabMergeRequestDescription
gitlabMergeRequestId
gitlabMergeRequestIid
gitlabMergeRequestState
gitlabMergedByUser
gitlabMergeRequestAssignee
gitlabMergeRequestLastCommit
gitlabMergeRequestTargetProjectId
gitlabTargetBranch
gitlabTargetRepoName
gitlabTargetNamespace
gitlabTargetRepoSshUrl
gitlabTargetRepoHttpUrl
gitlabBefore
gitlabAfter
gitlabTriggerPhrase

Just as you would read Jenkins job parameters from Jenkins Global Variable params in your job pipeline script, you could read webhook payload fields from Jenkins Global Variable env :

echo "My Jenkins job parameter is ${params.MY_PARAM_NAME}"
echo "One of Jenkins job webhook payload field is ${env.gitlabTargetBranch}"

Hope, the above information helps solve your problem.

Answer 3

Yes, I did it. And it works for some scenarios.

If you use /gitlab/buildnow, you can have access to payload objects. All of them. But you have to name them under "this build is parametrized". Then you can access them by name, like ${AUTHOR_NAME}.

Doc: https://github.com/elvanja/jenkins-gitlab-hook-plugin#parameterized-projects

But please note that if you use /gitlab/notifycommit, it will not work, since there is a gap (the poll) between triggering jenkins, and actually starting the job. All payload data in this situation is empty.

But be carefull to use /gitlab/buildnow, because you cannot control if you want or not to build, like when Maven commit back some files, and build is not supposed to be triggered.

What I did was to write a little tool in Python to receive all gitlab notification, and this tool talks back to GitLab and Jenkins, to fire (or not) jobs, and collect back statuses.

My start point: How do I receive Github Webhooks in Python (last answer, not the choosen one).

I started developing it 2 days ago. It's done, but I am still validating it.