Fixes #38072 - add host bootc_images endpoint

[ianballou]

What are the changes introduced in this pull request?

Adds a new /hosts/bootc_images endpoint that returns an overview of all bootc images that hosts are using.

The return data looks like the following:

{
  "total": 499,
  "bootc_images": [
    [
      "quay.io/centos-bootc/centos-bootc:stream10",
      [
        {
          "bootc_booted_digest": "sha256:54256a998f0c62e16f3927c82b570f90bd8449a52e03daabd5fd16d6419fd572",
          "host_count": 1
        }
      ]
    ]
  ]
}

This data will power a page that shows a list of image paths and each image mode host that is using that image path. Since each host could use the same image but a different digest, each image path holds any number of digests with the count of hosts that are using that digest. More digests per image path means more drift from the latest container content under that container tag.

Considerations taken when implementing this change?

Choosing where this goes was difficult -- it's related to hosts so I decided to stick it under the hosts endpoint. I use facts as a similar paradigm: host facts and bootc images are both aggregate information from hosts that are available at a single API endpoint.

What are the testing steps for this pull request?

1. Make a bunch of different bootc hosts. You can use the following script to create one clone:

#!/bin/bash

uuid=$(uuidgen)
short=$(hostname -s)
domain=manicotto.example.com
echo "{\"dmi.system.uuid\": \"${uuid}\"}" > /etc/rhsm/facts/uuid.facts
hostnamectl set-hostname ${short}.${uuid%%-*}.${domain}
subscription-manager clean
subscription-manager register --activationkey "Default Library Key" --org "Default_Organization"

2. Query the endpoint, test with and without paging

curl "https://`hostname`/api/hosts/bootc_images?per_page=5&page=7" -uadmin:pass

3. Ensure that empty conditions work, check page sizes that don't make sense, etc.

[ianballou]

Rubocop errors are unrelated & on master.

[sjha4]

Does it make sense to add filtering params to this API endpoint? Like filter for hosts or digest etc?

[ianballou]

Does it make sense to add filtering params to this API endpoint? Like filter for hosts or digest etc?

I think it makes sense, it would enable there to be a search bar in the UI.

Question is, which params should we support? Perhaps:

• Host name
• Container image path
• Container image digest

[ianballou]

I'm thinking I might need to make some changes to how the returned data is structured to better suit UI development. Seems like more keys might be expected. I'd also like to follow the general standard we have where results is the top-level key.

"name" before the image path might be one key I should add.

[ianballou]

I've added full support for scoped_search searching via the Host::Managed model. My only regret is that I have to load up the host IDs first and then create the content facets query, but I don't see a good way yet to combine the two queries into one.
The performance with 6579 hosts still seems fine.