Respect core.add-remotes-config-dir configuration option when adding remotes

[pwithnall]

There are currently a couple of places in common/flatpak-dir.c where ostree_repo_write_config() is called to add per-remote configuration to the OSTree configuration. This won’t work if the repository is configured with core.add-remotes-config-dir=true. For the moment, OSTree sets core.add-remotes-config-dir=false by default for non-system repositories (such as flatpak repositories). However, on systems where the OSTree and flatpak repositories are shared (such as Endless OS), this can cause problems if core.add-remotes-config-dir=false isn’t explicitly configured. Problems like flatpak remote-add failing:

$ sudo flatpak remote-add new-remote http://example.com/
error: Remote "new-remote" already defined in /etc/flatpak/remotes.d/new-remote.conf

The problem is that ostree_repo_remote_[add|change]() will preferentially write remote config to /etc/ostree/remotes.d/ (or wherever the configured remote-config-dir is), if core.add-remotes-config-dir=true. But ostree_repo_write_config() will always modify $repo_dir/config.

Since late last year, calls to ostree_repo_write_config() will error out if core.add-remotes-config-dir=true is set, but the config provided to it contains remotes which are already defined in /etc/ostree/remotes.d. This prevents the system getting into a bad state, but it does mean that flatpak remote-add is broken (it will not succeed, and will leave a partially-configured remote behind when it fails).

Two functions in common/flatpak-dir.c are currently affected:

• flatpak_dir_modify_remote()
• flatpak_dir_install_bundle()

For example, if I have:

$ cat /ostree/repo/config && ls -laR /etc/*/remotes.d
[core]
repo_version=1
mode=bare
add-remotes-config-dir=true
min-free-space-percent=0

[remote "flathub"]
url=https://dl.flathub.org/repo/
xa.title=Flathub
gpg-verify=true
gpg-verify-summary=true

/etc/ostree/remotes.d:
total 8
drwxr-xr-x 2 root root 4096 May 11 10:59 .
drwxr-xr-x 3 root root 4096 May 11 10:59 ..

Then I run:

$ sudo flatpak remote-add new-remote http://example.com/
error: Remote "new-remote" already defined in /etc/flatpak/remotes.d/new-remote.conf

I end up with:

$ cat /ostree/repo/config && ls -laR /etc/*/remotes.d
[core]
repo_version=1
mode=bare
add-remotes-config-dir=true
min-free-space-percent=0

[remote "flathub"]
url=https://dl.flathub.org/repo/
xa.title=Flathub
gpg-verify=true
gpg-verify-summary=true

/etc/flatpak/remotes.d:
total 12
drwxr-xr-x 2 root root 4096 May 11 14:23 .
drwxr-xr-x 3 root root 4096 May 11 14:18 ..
-rw-r--r-- 1 root root   46 May 11 14:23 new-remote.conf

/etc/ostree/remotes.d:
total 8
drwxr-xr-x 2 root root 4096 May 11 10:59 .
drwxr-xr-x 3 root root 4096 May 11 10:59 ..
$ cat /etc/flatpak/remotes.d/new-remote.conf 
[remote "new-remote"]
url=http://example.com/

[dbnicholson]

Another option is to finish off ostreedev/ostree#1166 so that flatpak can do sane remote modification instead of doing the "add remote with just URL if it doesn't exist then set options via ostree_repo_copy_config()/ostree_repo_write_config() dance".

[pwithnall]

That would be the best option. I don’t have time to work on that at the moment though. :-(

[mwleeds]

@pwithnall this can be closed, right?

[pwithnall]

@pwithnall this can be closed, right?

Nope, the right fix is to modify the file which contains the particular remote config, rather than unconditionally modifying $repo_dir/config. The ‘fix’ I pushed in 21e219b just returns an error message in the dodgy case, rather than actually doing the right thing.

The long-term fix here is probably ostreedev/ostree#1166, but I’ll leave it for Alex to decide whether to defer to 1166, or whether to fix this in flatpak in the interim.