Gitlab
What are the tools and libraries that work for Gitlab ?
If you want to see packages to interfere with Git, see its own git page.
For Github, see Github, and see also the Git interface Magit and VC, the built-in version control system.
Packages
Get the list of opened issues, special commit mode
See git-commit-insert-issue, which works for Github and Gitlab (in the dev branch though). It has a commit minor mode which automatically fetches the opened issues when you type something like "Fixes #" in the commit message.