Here's a short check-list for releases:
Update the .mailmap and AUTHORS files:
$ git log --use-mailmap | grep ^Author: | cut -f2- -d' ' | sort | uniq > AUTHORS
Update the version number in the icinga2.spec file.
Update the ChangeLog, doc/1-about.md files using the changelog.py script.
Commit these changes to the "master" branch:
$ git commit -v -a -m "Release version <VERSION>"
For minor releases: Cherry-pick this commit into the "support" branch.
Create a signed tag (tags/v) on the "master" branch (for major releases) or the "support" branch (for minor releases).
GB:
$ git tag -u EE8E0720 -m "Version <VERSION>" v<VERSION>
MF:
$ git tag -u D14A1F16 -m "Version <VERSION>" v<VERSION>
Push the tag.
$ git push --tags
For major releases: Create a new "support" branch:
$ git checkout master
$ git checkout -b support/2.x
$ git push -u origin support/2.x