Use hawkey/librepo (libhif?) about rpm-ostree

[cgwalters]

I have a WIP branch on this here: https://github.com/cgwalters/rpm-ostree/tree/wip/hawkey-librepo that I'm slowly playing with on the side.

[cgwalters]

Using libhif ( https://github.com/hughsie/libhif )

Oriented towards mutating current system

With rpm-ostree, we're going for a model where we always construct a new tree for any system mutation - no changes are applied live. But libhif is pretty oriented towards being a backend for PackageKit which does live system changes.

I kept hitting places in libhif where it would load the system RPM database, such as the keyrings.

And places where it (or hawkey) would bomb out trying to create a new root.

This should all be fixable.

Though actually this gets into an interesting question - for compose tree, where do we find the trusted GPG keyring? And clearly for rpm-ostree, it won't work to store the trusted keys in the system RPM database.

Would like to be able to more easily synthesize configuration passed in

We have hif_context_set_repo_dir() but currently with "rpm-ostree compose tree" I don't have enabled=1 in the .repo files. Though I could.

Need deep control over RPM installation

This is a big one. I can't use HifTransaction as is, because I need to inspect the RPM packages. I'd also like finer grained control over download phase versus installation in general.

I don't need support for removals, because in the rpm-ostree package layering model you can't do that - you instead construct a new tree that doesn't have that package to start with.

Currently not privilege separated

My prototype of using librepo does the fetches as an unprivileged user (default "bin"), communicating over dbus

Need to figure out a concurrency design

This is not a libhif bug, but it'd be really nice if we had an "rpm-ostree compose docker" that could be run multiple times concurrently, and automatically cached metadata and packages shared between the two. (And for that matter, with compose tree and with the host system updates too)

[cgwalters]

@hughsie ^

[cgwalters]

New (working) branch: https://github.com/cgwalters/rpm-ostree/commits/wip/libhif

[cgwalters]

This is done in master.