RPM Support

The first time Pulp uses a distributor to publish a repository, it checks if the distributor has a checksum type configured. This value determines which checksum type is published with repo metadata. If this value is not set, Pulp looks up the checksum type stored in repository 'scratchpad'. Pulp then configures the distributor with the value found in the scratchpad. This means that if the checksum type changes in the scratchpad because the upstream repository changed what it is publishing, Pulp will continue trying publish with the original checksum type. This is a problem for repositories that use the 'on_demand' download policy. An on_demand repository may be first synced and published using SHA1 checksums. When the upstream repository starts publishing SHA256 checksums, Pulp downloads the new metadata with the SHA256 checksums, but when it tries to publish, it attempts to publish the SHA1 checksums that it no longer has. Since it is an on_demand repository, it can't calculate the SHA1 checksum from files that haven't been downloaded. This is when Pulp emits RPM1008 exception.

My initial thought was to not set the distributor checksum in get_repo_checksum_type(). However, doing some research, I found that this code was created to solve a use case whereby repos are being copied and the checksum type must be preserved. From https://bugzilla.redhat.com/show_bug.cgi?id=1029057#c16:

Currently, the yum importer notices the use of sha1 upstream and makes a note of it in the repo scratchpad. The distributor then sees the note and publishes with sha1. The problem is that when copying content, attributes of the repo (such as its scratchpad) are not copied. This is by design, but makes this particular use case difficult.
The solution is that when the distributor sees the note in the scratchpad, it will look at its own config, and if a checksum has not been set, it will save the checksum in its config. This allows someone who wants to create a copy of a repo to copy the distributor's config, and thus take advantage of this checksum detection.

I'm a bit unsure of how to solve this bug and not break the use case mhrivnak describes. Thoughts?

Looks like we began exposing the repo scratchpad a while ago:

https://pulp.plan.io/issues/1172

Therefore, we should not automatically set the checksum_type on distributor. It looks like we were setting it to expose the value to users. However, it has unintended side effects and now there's another way to view the repository's checksum type (which is set in the scratchpad).

Applied in changeset 36d08173239f3c3767bc2e00bbe5ec71a0e53176.