Generate list of all Merge Requests merged between two tags with all informations in csv file

I've written a small Python script to do this. Usage:

git log --pretty="format:%H" <start>..<end> | python collect.py

Script:

#!/usr/bin/env python

import sys
import requests

endpoint = 'https://gitlab.com'
project_id = '4242'

mrs = set()
for line in sys.stdin:
    hash = line.rstrip('\n')
    r = requests.get(endpoint + '/api/v4/projects/' + project_id + '/repository/commits/' + hash + '/merge_requests')
    for mr in r.json():
        if mr['id'] in mrs:
            continue
        mrs.add(mr['id'])

        print('!{} {} ({})'.format(mr['iid'], mr['title'], mr['web_url']))

For now, this is not yet between two tags, but you have, with GitLab 13.6 (November 2020):

Export merge requests as a CSV

Many organizations are required to document changes (merge requests) and the data surrounding those transactions such as who authored the MR, who approved it, and when that change was merged into production. Although not an exhaustive list, it highlights the recurring theme of traceability and the need to export this data from GitLab to serve an audit or other regulatory requirement.

Previously, you would need to use GitLab’s merge requests API to compile this data using custom tooling. Now, you can click one button and receive a CSV file that contains the necessary chain of custody information you need.

See Documentation and Issue.