Re: Dealing with corporate email recycling

From: Sean Allred <allred.sean@gmail.com>
Date: Mar 13, 2022, 14:41 UTC
Message-ID: <87v8whap0b.fsf@gmail.com>
In-Reply-To: <01f201d836e5$89247c30$9b6d7490$@nexbridge.com>

<rsbecker@nexbridge.com> writes:

Show 15 quoted lines

> (I am a little nervous about this advice, hoping others will chime in and
> correct anything wrong here)
>
> While this will change the commit hashes, AFAIK, the other metadata is
> preserved, including date, author, and committer. Set up the specific
> keys/settings in ssh-agent and the user.signingKey value, then:
>
> git filter-branch --commit-filter 'git commit-tree -S "$@";'
> <FROM-COMMIT>..<TO-COMMIT>
>
> Others might have a better way of doing this or may tell me this will not
> work. Test this before you do it. I have not done this operation before. You
> do need to start from the oldest commit going forward otherwise I think that
> filter-branch will (should!) invalidate child commits. I suspect this is
> going to be a rather lengthy script to build and run.

Given the size of our history (several orders of magnitude larger than linux.git), using git-filter-branch after the fact is certainly not ideal. The replay already takes a week to run (we're IO-bound). We'd rather want to extend git-fast-import to allow signing commits instead -- which comes back to our shared 'nervousness' about this approach in general: I don't know that Git should endorse this as a standard option.

But yes -- hoping others can chime in with more thoughts :-)

-- Sean Allred