Re: Reducing Git Repository size - git-filter-repo doesn't help

[Elijah Newren <newren@gmail.com>]

On Tue, Jan 10, 2023 at 12:18 AM fawaz ahmed0 <fawazahmed0@hotmail.com> wrote:
>
>
> > Note that git-filter-repo only changes the size of the _local_ repo.
>    You made an additional clone within GitHub Actions, and then
>    filter-repo shrinks *that* clone.  Even if you had deleted all copies
>    of older files you don't want anymore locally (which is suspect as I
>    noted above), your force pushing isn't going to shrink the size of the
>    repo on the server (i.e. on GitHub) since there are pull requests in
>    your repo that GitHub won't allow you to overwrite via force-push, and
>    those pull requests still hold on to the old history.
>
> Thanks for your inputs. Yes, the issue is with the GitHub itself (I have verified it locally), so when I force push this reduced sized repo to Github and reclone it back the size gets back to  4+ GB.
> So what do you suggest?

Well, digging a bit further, I see:
```
$ git ls-remote https://github.com/fawazahmed0/currency-api
5536f2096aec71cee6d35772697ce1efc6148521 HEAD
5536f2096aec71cee6d35772697ce1efc6148521 refs/heads/1
7ed955eebe2e5a670566d5fb4e11142bae6afed6 refs/heads/patch-1
0292ec7340ec1ac8cd11d5839b8a25dd0c1db38f refs/pull/1/head
fa18a4ae50cc8ad84643d1f1f92da77c35139bbc refs/pull/16/head
bca74c53f66681f2d74a98d2f785e1610abeb794 refs/pull/18/head
4da5bcd8c7852bb306059a856f95e9bc1aeaefd3 refs/pull/47/head
5f1408be857734745a7a3349e9d16a8200e993be refs/pull/49/head
00ff16478e95f11347bc3e769e310c1a254579c9 refs/pull/57/head
5e3121acaddc7be810f2b9ad92641a04f9b923fb refs/pull/58/head
8afe04f52b8174c789691b4097c70f95d33c99c4 refs/pull/59/head
55b0d38d156145d8f9726746da7bb4d5ba9d988c refs/pull/60/head
bca74c53f66681f2d74a98d2f785e1610abeb794 refs/reviewable/pr18/r1
4da5bcd8c7852bb306059a856f95e9bc1aeaefd3 refs/reviewable/pr47/r1
5f1408be857734745a7a3349e9d16a8200e993be refs/reviewable/pr49/r1
00ff16478e95f11347bc3e769e310c1a254579c9 refs/reviewable/pr57/r1
5e3121acaddc7be810f2b9ad92641a04f9b923fb refs/reviewable/pr58/r1
8afe04f52b8174c789691b4097c70f95d33c99c4 refs/reviewable/pr59/r1
55b0d38d156145d8f9726746da7bb4d5ba9d988c refs/reviewable/pr60/r1
```

So, you have 19 references.  And according to the output of the job
you linked, you only force pushed refs/heads/1.  That means the other
branches and refs are holding on to the old history.  You'll either
need to delete or rewrite refs/heads/patch-1, and
refs/reviewable/pr{18,47,49,57,58,59,60}/r1 as well.  Rewriting the
refs/reviewable stuff may confuse and mess up Reviewable if you ever
look at those reviews again; it may be that deleting those refs
results in a cleaner error message within Reviewable.

You also need to have refs/pull/{1,16,18,47,49,57,58,59,60}/head all
rewritten too, but you don't have access.  You need to get GitHub
support to do that.  If they don't ask for the exact filtering you
have done, and are only "clearing caches", then it's not going to do
anyone any good.  Those references need to be filtered the same way,
or else those special refs need to be deleted.  But please do note
that you should not ask them to do that until you've already cleaned
up all the stuff that you can.

The steps look roughly as follows:

1. Clone the repository.  Since you have refs outside of refs/heads/
and refs/tags/ (namely refs/reviewable/), you'll need a mirror clone.
Also, make sure to NOT use a partial clone (which would defeat steps 2
& 5).
2. Note the size of the *local* clone ('du -hs' should come in handy).
3. Run `python3 git-filter-repo --analyze`, and look at the reports it
generates to find out the big files/directories and all the names of
those paths.
4. Filter the repository.
5. Verify that the local clone actually shrinks from your filtering
operation (not just has fewer commits, but 'du -hs' now reports a much
smaller number).  If it does not shrink as much as expected, run
`python3 git-filter-repo --analyze` again and see if you missed
alternate historical names of some files or whether you only filtered
what turned out to be small files or whatever.

Note that step 3 is important.  Rather than guessing what is big and
taking up lots of space, you find out what is big and take action upon
it.  For example, you once committed the node_modules/ folder.  I do
not know its size (too lazy to do a full clone and find out), but
those are often quite large.  Creating a commit that deletes that
directory does not remove it from history, only from the current
version.  So, expunging that directory from history may be important.
There may be other nuggets you find too, such as alternate names of
files that also need to be deleted if you've renamed things.

After you've succeeded with all the above:
6. force push *all* references back to GitHub -- or at least the ones
that GitHub will permit you to force push (should be everything other
than refs/pull/*).  If you only force push your "1" branch, you still
leave every other reference holding on to the old history.
7. Contact GitHub support to ensure they clean up the remaining
references (i.e. the refs/pull/* ones) _and_ clear their caches.  They
will either have to ask for what filtering you did so they can do it
as well, or they'll need to nuke those pull requests.
8. Wait to hear back
9. Check the `git ls-remote
https://github.com/fawazahmed0/currency-api` output again.  If the
refs/pull/* lines still exist and still have the same hashes at the
beginning of their lines, GitHub did not filter those references and
they are still holding on to the old history.  Contact them again, and
either get them to filter those refs the same way you filtered yours,
or get them to delete those pull requests.

> I have already contacted Github few days back, and they have cleared the cache etc for this repo.(but that did not reduce any size). ( I will try contacting them again)

Contacting them now is a waste of their time.  Filter your repo first.
Your whole repo (implying you need a mirror clone rather than a
regular clone given you have the unusual refs/reviewable/* references
that need filtering too).  And push the whole repo back, not just a
single branch.