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Hide git-annex branch #45

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@matrss matrss commented Nov 3, 2023

Fixes #4.

So far, this hides the git-annex branch from showing up in the branch dropdown of a repository as well as the dedicated branches list page (the counter there is off though). The messages in the dashboard are also filtered to exclude actions related to the git-annex branch. The "banner" to open a PR for the git-annex branch if it was recently pushed to is removed too, together with the "create a PR" message you get on first push to that branch.

These changes are only visual, the routes for the git-annex branch still work. But you would need to deliberately navigate to a repository's git-annex branch or the branch compare page with git-annex as one of the branches to see them. I don't think that is too much of a concern.

I'll have to do some reading on how synced/* and adjusted/* branches should be handled, and whatever else git-annex might create.

kousu and others added 8 commits November 8, 2023 13:11
[git-annex](https://git-annex.branchable.com/) is a more complicated cousin to
git-lfs, storing large files in an optional-download side content.  Unlike lfs,
it allows mixing and matching storage remotes, so the content remote(s) doesn't
need to be on the same server as the git remote, making it feasible to scatter
a collection across cloud storage, old harddrives, or anywhere else storage can
be scavenged.  Since this can get complicated, fast, it has a content-tracking
database (`git annex whereis`) to help find everything later.

The use-case we imagine for including it in Gitea is just the simple case, where
we're primarily emulating git-lfs: each repo has its large content at the same URL.

Our motivation is so we can self-host https://www.datalad.org/ datasets, which
currently are only hostable by fragilely scrounging together cloud storage --
and having to manage all the credentials associated with all the pieces -- or at
https://openneuro.org which is fragile in its own ways.

Supporting git-annex also allows multiple Gitea instance to be annex remotes for
each other, mirroring the content or otherwise collaborating the split up the
hosting costs.

Enabling
--------

TODO

HTTP
----

TODO

Permission Checking
-------------------

This tweaks the API in routers/private/serv.go to expose the calling user's
computed permission, instead of just returning HTTP 403.

This doesn't fit in super well. It's the opposite from how the git-lfs support is
done, where there's a complete list of possible subcommands and their matching
permission levels, and then the API compares the requested with the actual level
and returns HTTP 403 if the check fails.

But it's necessary. The main git-annex verbs, 'git-annex-shell configlist' and
'git-annex-shell p2pstdio' are both either read-only or read-write operations,
depending on the state on disk on either end of the connection and what the user
asked it to ask for, with no way to know before git-annex examines the situation.
So tell the level via GIT_ANNEX_READONLY and trust it to handle itself.

In the older Gogs version, the permission was directly read in cmd/serv.go:

```
mode, err = db.UserAccessMode(user.ID, repo)
```
- https://github.com/G-Node/gogs/blob/966e925cf320beff768b192276774d9265706df5/internal/cmd/serv.go#L334

but in Gitea permission enforcement has been centralized in the API layer.
(perhaps so the cmd layer can avoid making direct DB connections?)

Deletion
--------

git-annex has this "lockdown" feature where it tries
really quite very hard to prevent you deleting its
data, to the point that even an rm -rf won't do it:
each file in annex/objects/ is nested inside a
folder with read-only permissions.

The recommended workaround is to run chmod -R +w when
you're sure you actually want to delete a repo. See
https://git-annex.branchable.com/internals/lockdown

So we edit util.RemoveAll() to do just that, so now
it's `chmod -R +w && rm -rf` instead of just `rm -rf`.
Fixes neuropoly#11

Tests:

* `git annex init`
* `git annex copy --from origin`
* `git annex copy --to origin`

over:

* ssh

for:

* the owner
* a collaborator
* a read-only collaborator
* a stranger

in a

* public repo
* private repo

And then confirms:

* Deletion of the remote repo (to ensure lockdown isn't messing with us: https://git-annex.branchable.com/internals/lockdown/#comment-0cc5225dc5abe8eddeb843bfd2fdc382)

------

To support all this:

* Add util.FileCmp()
* Patch withKeyFile() so it can be nested in other copies of itself

-------

Many thanks to Mathieu for giving style tips and catching several bugs,
including a subtle one in util.filecmp() which neutered it.

Co-authored-by: Mathieu Guay-Paquet <[email protected]>
This makes HTTP symmetric with SSH clone URLs.

This gives us the fancy feature of _anonymous_ downloads,
so people can access datasets without having to set up an
account or manage ssh keys.

Previously, to access "open access" data shared this way,
users would need to:

  1. Create an account on gitea.example.com
  2. Create ssh keys
  3. Upload ssh keys (and make sure to find and upload the correct file)
  4. `git clone [email protected]:user/dataset.git`
  5. `cd dataset`
  6. `git annex get`

This cuts that down to just the last three steps:

  1. `git clone https://gitea.example.com/user/dataset.git`
  2. `cd dataset`
  3. `git annex get`

This is significantly simpler for downstream users, especially for those
unfamiliar with the command line.

Unfortunately there's no uploading. While git-annex supports uploading
over HTTP to S3 and some other special remotes, it seems to fail on a
_plain_ HTTP remote. See neuropoly#7
and https://git-annex.branchable.com/forum/HTTP_uploads/#comment-ce28adc128fdefe4c4c49628174d9b92.

This is not a major loss since no one wants uploading to be anonymous anyway.

To support private repos, I had to hunt down and patch a secret extra security
corner that Gitea only applies to HTTP for some reason (services/auth/basic.go).

This was guided by https://git-annex.branchable.com/tips/setup_a_public_repository_on_a_web_site/

Fixes neuropoly#3

Co-authored-by: Mathieu Guay-Paquet <[email protected]>
This moves the `annexObjectPath()` helper out of the tests and into a
dedicated sub-package as `annex.ContentLocation()`, and expands it with
`.Pointer()` (which validates using `git annex examinekey`),
`.IsAnnexed()` and `.Content()` to make it a more useful module.

The tests retain their own wrapper version of `ContentLocation()`
because I tried to follow close to the API modules/lfs uses, which in
terms of abstract `git.Blob` and `git.TreeEntry` objects, not in terms
of `repoPath string`s which are more convenient for the tests.
Previously, Gitea's LFS support allowed direct-downloads of LFS content,
via http://$HOSTNAME:$PORT/$USER/$REPO/media/branch/$BRANCH/$FILE
Expand that grace to git-annex too. Now /media should provide the
relevant *content* from the .git/annex/objects/ folder.

This adds tests too. And expands the tests to try symlink-based annexing,
since /media implicitly supports both that and pointer-file-based annexing.
This updates the repo index/file view endpoints so annex files match the way
LFS files are rendered, making annexed files accessible via the web instead of
being black boxes only accessible by git clone.

This mostly just duplicates the existing LFS logic. It doesn't try to combine itself
with the existing logic, to make merging with upstream easier. If upstream ever
decides to accept, I would like to try to merge the redundant logic.

The one bit that doesn't directly copy LFS is my choice to hide annex-symlinks.
LFS files are always _pointer files_ and therefore always render with the "file"
icon and no special label, but annex files come in two flavours: symlinks or
pointer files. I've conflated both kinds to try to give a consistent experience.

The tests in here ensure the correct download link (/media, from the last PR)
renders in both the toolbar and, if a binary file (like most annexed files will be),
in the main pane, but it also adds quite a bit of code to make sure text files
that happen to be annexed are dug out and rendered inline like LFS files are.
Upstream can handle the full test suite; to avoid tedious waiting,
we only test the code added in this fork.
This hides the git-annex branch as well as the synced/* branches from
many places in the UI where branches are otherwise shown. This includes
e.g. the dropdown menu on the repo page and when comparing different
branches, or the dedicated branches page of a repository.
This prevents actions that belong to the git-annex branch or synced/*
branches from showing up in e.g. the users activity feed.
This hides the banner you can see on a repositories page that proposes
to open a PR for your branch if you recently pushed to said branch, but
only if that branch is named git-annex or starts with synced/.
This hides the message with a link to open a new PR that you normally
get when pushing to a new branch if you push to a newly created
git-annex or synced/ branch.
@matrss
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matrss commented Nov 8, 2023

This also hides synced/* branches now.

The things left from what was discussed in #4 are:

  • webhooks
  • the branch routes returning 404

I don't see much of a point in also removing the corresponding branch routes entirely. With the changes so far it should not be possible to reach those routes from UI navigation alone.

Regarding webhooks, I think there might even be use-cases to consuming webhooks that are triggered by pushes to those special branches. E.g. maybe someone wants to hook up an external system that does some kind of visualization of where data is located (or where git-annex thinks it is located, anyway), which would depend on the state of the git-annex branch. Or maybe every change on the git-annex branch really should be a message in a Slack channel. Since one would have to actively configure those webhooks I think it is reasonable to assume that they will think about how they want to handle these special branches.

Looking at the webhook configuration page though, it seems like it would be impossible to specify excludes for git-annex and synced/* and trigger the hook on all other branches; it is only possible to specify a whitelist, not a blacklist of branches... Maybe this is something that should be expanded in upstream gitea.

@matrss matrss marked this pull request as ready for review November 8, 2023 14:24
@gitea-sync gitea-sync bot force-pushed the git-annex branch 3 times, most recently from 81f56b1 to d75a62f Compare November 11, 2023 13:09
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