The `repo:gc` command doesn't work on heroku-24 stack

[nickcoyne]

With the removal of git from the heroku-24 stack at runtime, heroku-repo commands no longer work.

Some documentation on a workaround would be appreciated.

[edmorley]

Hi! Thank you for filing this.

Checking the various heroku-repo Git related commands, the only one I can see that uses git at runtime is heroku repo:gc:

heroku-repo/commands/gc.js

Lines 16 to 24 in b5876bd

	mkdir -p tmp/repo_tmp/unpack
	cd tmp/repo_tmp
	curl -fo repo.tgz '${yield repo.getURL(app)}'
	cd unpack
	tar -zxf ../repo.tgz
	git gc --aggressive
	tar -zcf ../repack.tgz .
	curl -fo /dev/null --upload-file ../repack.tgz '${yield repo.putURL(app)}'
	exit`

...since the heroku repo:reset command instead simply issues a DELETE to the API:

heroku-repo/commands/reset.js

Lines 7 to 12 in b5876bd

	let r = heroku.request({
	method: 'DELETE',
	path: `/${context.app}.git`,
	host: `git.${context.gitHost}`,
	parseJSON: false
	})

...and heroku repo:clone uses Git from the host machine instead:

heroku-repo/commands/clone.js

Lines 25 to 27 in b5876bd

	exec('git init', {stdio: 'inherit'})
	exec('git reset --hard master', {stdio: 'inherit'})
	exec(`git remote add heroku ${info.git_url}`, {stdio: 'inherit'})

Regarding repo:gc specifically, I'm a bit unsure why we even need that command? It seems that a simpler way to resolve a bloated remote repo would be to repo:reset and then git push heroku main again - since gc only compacts the repo slightly and doesn't purge unused branches etc.

Perhaps we should just deprecate/sunset repo:gc in favour of telling people to repo:reset?

[nickcoyne]

Thanks for the response. repo:gc is the one I use fairly regularly. We have a rather large app and I need to gc every week or two to keep the slug size under control.

Typically I'll run these two commands sequentially:

heroku repo:gc
heroku repo:purge_cache

[edmorley]

repo:gc will have no effect on slug size fwiw. The Git repo metadata isn't even sent to the build system, so doesn't go anywhere near the slug or build cache.

[nickcoyne]

In that case repo:gc is far less important to me. So perhaps your deprecation/sunset suggestion is the best path forward.

[edmorley]

Searching both the Heroku Help site KB articles and Heroku Dev Center I found zero mentions of heroku repo:gc, so in general I don't think it's a feature we advertise ourselves, outside of this repo's README.

However, searching the general internet I do find a handful of well-meaning but incorrect articles mentioning repo:gc as one of several steps for improving slug size (eg alongside the more helpful build cache clearing step). Ideally those articles would instead link to eg:
https://help.heroku.com/KUFMEES1/my-slug-size-is-too-large-how-can-i-make-it-smaller
https://devcenter.heroku.com/articles/slug-compiler#slug-size

[nickcoyne]

Thanks @edmorley! I'm sure I would have been following one of those articles. The official resources you've listed are far more useful. Cheers