How can files be added to a tarfile with Python, without adding the directory hierarchy?

Using the arcname argument of TarFile.add() method is an alternate and convenient way to match your destination.

Example: you want to archive a dir repo/a.git/ to a tar.gz file, but you rather want the tree root in the archive begins by a.git/ but not repo/a.git/, you can do like followings:

archive = tarfile.open("a.git.tar.gz", "w|gz")
archive.add("repo/a.git", arcname="a.git")
archive.close()

You can use tarfile.addfile(), in the TarInfo object, which is the first parameter, you can specify a name that's different from the file you're adding.

This piece of code should add /path/to/filename to the TAR file but will extract it as myfilename:

tar.addfile(tarfile.TarInfo("myfilename.txt"), open("/path/to/filename.txt"))

Maybe you can use the "arcname" argument to TarFile.add(name, arcname). It takes an alternate name that the file will have inside the archive.