Changelog Tools

• Background
• Usage

Background

Our (@SvenPatrick and my) fundamental idea is to create the changelog for a GitLab release automatically after pushing a Git tag using a GitLab CI pipeline (see also the uulmhack/pipelines/auto-create-release project). The original implementation is/was based on the following simple one line shell command:

git diff --unified=0 HEAD~1 ./CHANGELOG.md | tail -n +6 | sed -e "s/^+//"

This relies on the fact, that the CHANGELOG.md file was touched in the last commit before tagging and does not handle multiple changed blocks well. The tools in this project try to provide a more general solution for this.

The (initial) Python implementation is only made as a proof-of-concept and as of now works for the tests I have run. The next, intermediate tasks for this would include (automatic) tests. In the long run the goal would be a merge request into the gitlab-org/release-cli project which would require a rewrite using the Go programming language.

Usage

The project currently consists of three scripts whereby latest_changelog.py can be seen as the main entry point. Nevertheless it is possible to run all three scripts on its own and also the do not have any dependencies besides itself and modules of the standard library. It is of course required to execute the files while being in a Git repository.

The latest_tags.py returns a chronologically sorted list of templates in the current Git repository. changelog_diff.py takes two arguments specifying the old and the newer revision to diff between and an optional third argument to the file to diff (this defaults to CHANGELOG.md). The script returns the changes lines from the file between the two given revisions. Thereby the diff is filtered to exclude single line changes since it is assumed that these only contain typo fixes or other not noteworthy changes.

The latest_changelog.py finally combines the two scripts to output the relevant part of the changelog between the last two tags in the current Git repository.