How to add comments to Gitlab 'Merge Request' from CI script

Posted by Daniel Vela on November 13, 2018

This doc was made to explain how to send the output of an script (like swiftlint or other lints or quality utils) from the CI process of Gitlab to the Merge Request comment list.

At 13 Nov 2018 Gitlab don’t have a enviroment variable to know the iid of the merge request. Look this StackOverflow question to see more info.

But this iid can be obtained using the Gitlab API. The trick is to query the merge request list from a commit and use the first one.

Gitlab API doc

  1. Create new merge request comment
  2. Basic usage
  3. List Merge Requests associated with a commit

API Usage Sample :

POST /projects/:id/merge_requests/:merge_request_iid/notes

$ curl --request POST --header "Private-Token: 9koXpg98heJpvBs5tK" --data "Comment test"


  • Install xcpretty

      $ brew install xcpretty
  • Install jq to parse json response

      $ brew install jq
  • Install swiftlint

      $ brew install swiftlint
  • Set your API gitlab private token
    Create a token in your Gitlab profile:

    Set a new environment variable in the file config.toml of your gitlab runners.

concurrent = 1
check_interval = 0
  name = "mac-mini.local"
  url = ""
  token = "d1c0dd187cf73f7e8480cc7ef4a0f4"
  tls-ca-file = "/Users/pepe/"
  executor = "ssh"
  environment = ["GITLAB_PERSONAL_API_PRIVATE_TOKEN=L8zHc7asdfffp2k18hX9Fu"]
    user = "pepe"
    password = "pepe"
    host = "localhost"
    port = "22"
    identity_file = "/Users/pepe/.ssh/id_rsa"


This is a sample .gitlab-ci.yml file to send the swiftlint output to the Merge Request comments:

  stage: build
    - echo "body=" > swiftlint.log
    - swiftlint >> swiftlint.log
    - 'CI_MERGE_REQUEST_IID=$(curl --request GET --header "Private-Token: $GITLAB_PERSONAL_API_PRIVATE_TOKEN" "$CI_PROJECT_ID/repository/commits/$CI_COMMIT_SHA/merge_requests" --insecure | jq --raw-output ".[0].iid")'
    - '[ -z "$CI_MERGE_REQUEST_IID" ] && curl --request POST --header "Private-Token: $GITLAB_PERSONAL_API_PRIVATE_TOKEN" -d @swiftlint.log$CI_PROJECT_ID/merge_requests/$CI_MERGE_REQUEST_IID/notes --insecure'
    - unlink swiftlint.log
    - xcode

This scripts sets CI_MERGE_REQUEST_IID using the API to get the Merge Request for a commit using its $CI_COMMIT_SHA. The response is a json. To obtain the iid use jq --raw-output ".[0].iid".

Use [ -z "$CI_MERGE_REQUEST_IID" ] && to avoid send the POST if the commit doesn’t have any Merge Request associated.