OSTree Support

An ostree repository can contain lots of branches. The structure of the repository makes finding the branch names less than straight forward.

For exmaple:

[jortel@localhost el7]$ tree refs
refs
├── heads
│   └── rhel-atomic-host
│       └── 7
│           └── x86_64
│               ├── pulp
│               └── standard
└── remotes

5 directories, 2 files

The branch names are:

• rhel-atomic-host/7/x86_64/pulp
• rhel-atomic-host/7/x86_64/standard

When users are creating an ostree repository in Pulp, they need to specify the list of branches they want synced which is information that users don't necessarily know. Recently, ostree has added support for Summary Files. This is a file contained in the repo that lists the branches. It would be very helpful if Pulp could grab the Summary information and store it in Pulp repository notes or perhaps a more suitable place such as the importer scratchpad.

Example (something like):

Notes:
  Available Branches: [
    rhel-atomic-host/7/x86_64/pulp,
    rhel-atomic-host/7/x86_64/standard
  ]

The anticipated flow would be:

1. User creates the Pulp repository and does NOT specify any branches.
2. Sync the repository.
3. Look at the updated information (wherever it's stored).
4. Update the repository and specify the desired branches picked from the list.
5. Sync the repository.

The libostree API needs to be augmented to support fetching the summary. This has been communicated to the ostree team and can be tracked with this bug [1]. I would be good if the Summary file also contains the branch HEAD (commit) metadata so that properties such as version can be provided in additional to just the branch names. Summary files are optional so, Pulp will need to indicates that the information is not available when the Summary does not exist.

[1] https://bugzilla.gnome.org/show_bug.cgi?id=748059