ikiwiki/doc/todo/git-annex_support.mdwn

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A dear [[wishlist]] which would resolve [[this question|forum/ikiwiki_and_big_files]]: ikiwiki should support git-annex repositories.
I am not sure how this would work, but from my POV, it should do a `git annex get` when new commits are pushed to its bare repo. This would assume, of course, that there's another repo somewhere that ikiwiki has access to, which works for HTTP-style remotes, but could be more problematic for SSH remotes that require a key.
Another solution would be to make ikiwiki a remote itself and allow users to push big files to it. The only problem I see with this is those files would end up in the bare repository and not necessarily show up in the web rendering. Ideally, a big file pushed would be hardlinked between the two repos, but it seems [git-annex doesn't support that yet](http://git-annex.branchable.com/todo/wishlist:_use_hardlinks_for_local_clones). --[[anarcat]]
> One technical problem with this is that ikiwiki doesn't allow symlinks
> for [[security]], but git-annex relies on symlinks (unless you're in
> direct mode, but I'm not sure that's really desirable here).
> I'd like to make symlinks possible without compromising security,
> but it'll be necessary to be quite careful. --[[smcv]]
First implementation
====================
So as the [[discussion]] shows, it seems it's perfectly possible to actually do this! There's this [gallery site](http://stockholm.kalleswork.net) which uses the [[plugins/contrib/album]] plugin and git-annex to manage its files.
The crucial steps are:
1. setup a git annex remote in `$srcdir`
2. configure direct mode because ikiwiki ignores symlinks for [[security]] reasons:
cd $srcdir
git annex init
git annex direct
3. configure files to be considered by git-annex (those will be not committed into git directly):
git config annex.largefiles 'largerthan=100kb and not (include=*.mdwn or include=*.txt)'
4. make the bare repository (the remote of `$srcdir`) ignored by git-annex:
cd $srcdir
git config remote.origin.annex-ignore true
git config remote.origin.annex-sync false
(!) This needs to be done on *ANY* clone of the repository, which is annoying, but it's important because we don't want to see git-annex stuff in the bare repo. (why?)
5. deploy the following crappy plugin to make commits work again and make sure the right files are added in git-annex:
[[!format perl """
#!/usr/bin/perl
package IkiWiki::Plugin::gitannex;
use warnings;
use strict;
use IkiWiki 3.00;
sub import {
hook(type => "getsetup", id => "gitannex", call => \&getsetup);
hook(type => "savestate", id => "gitannex", call => \&rcs_commit);
# we need to handle all rcs commands maybe?
}
sub getsetup () {
return
plugin => {
safe => 1, # rcs plugin
rebuild => undef,
section => "misc",
},
}
# XXX: we want to copy or reuse safe_git
sub rcs_commit (@) {
chdir $config{srcdir};
`git annex add --auto`;
`git annex sync`;
}
sub rcs_commit_staged (@) {
rcs_commit($@);
}
1
"""]]
This assumes you know what `srcdir`, `repository` and so on mean, if you forgot (like me), see this reference: [[rcs/git/]].
What doesn't work
-----------------
* the above plugin is kind of flaky and ugly.
* it's not an RCS plugin, but probably should be, replacing the git plugin, because really: git doesn't work at all anymore at this point
What remains to be clarified
----------------------------
* how do files get pushed to the `$srcdir`? Only through the web interface?
* why do we ignore the bare repository?
See the [[discussion]] for a followup on that. --[[anarcat]]
Alternative implementation
==========================
An alternative implementation, which remains to be detailed but is mentionned in [[forum/ikiwiki_and_big_files]], is to use the [[underlay]] feature combined with the `hardlink` option to deploy the git-annex'd files. Then git-annex is separate from the base ikiwiki git repo. --[[anarcat]]