Fixes #36665 - Remove katello-agent API endpoints and rabl nodes

[jeremylenz]

What are the changes introduced in this pull request?

Remove Katello API endpoints that use katello-agent:

• /hosts/:host_id/errata/apply
• /hosts/:host_id/packages/install
• /hosts/:host_id/packages/upgrade
• /hosts/:host_id/packages/upgrade_all
• /hosts/:host_id/packages/remove
• /hosts/bulk/install_content
• /hosts/bulk/update_content
• /hosts/bulk/remove_content

Also remove katello-agent from api/ping.

Considerations taken when implementing this change?

This will break all related Hammer commands, so we should probably wait and merge the hammer-cli-katello PR at the same time as this one

What are the testing steps for this pull request?

Try existing hammer commands and confirm they're broken, I guess

[theforeman-bot]

Issues: #36665

[jturel]

I was admiring your work when it occurred to me that there's always a small chance that after all this cleanup is done, there may be "delete host agent queue" events in the db which will break the event queue when they get processed because their handler class will be removed. You'll need an upgrade rake task to delete those from the events table. Obviously, on the PR when you remove that stuff

[jeremylenz]

Yeah, I was just thinking about delete_host_agent_queue and how to handle that.. 😢

[parthaa]

Do we need that? Isn't the queue emptied when upgrading any way?

[jturel]

The queue isn't explicitly emptied on upgrade and there could be events on it especially for this specific case because it's scheduled to run ten minutes in the future. Any hosts unregistered ~10 minutes before shutdown will put the events on queue and if Katello is upgraded with that event removed it'll raise an error around an unsupported event. There could also be events stuck on the queue due to this bug: #10692

Looking at the code:

katello/app/services/katello/event_queue.rb

Lines 73 to 75 in c9fe25d

	def self.event_class(event_type)
	fail _("Invalid event_type %s") % event_type if @event_types[event_type].nil?
	@event_types[event_type].constantize

An error gets raised if an unsupported event is found on queue which is what will happen when the event's class is removed from the app. However, that error may be rescued, logged, and the event removed:

katello/app/services/katello/event_monitor/poller_thread.rb

Lines 61 to 70 in c9fe25d

	begin
	::User.as_anonymous_admin do
	event_instance = ::Katello::EventQueue.create_instance(event)
	event_instance.run
	end
	rescue => e
	@failed_count += 1
	@logger.error("event_queue_error: type=#{event.event_type}, object_id=#{event.object_id}")
	@logger.error(e.message)
	@logger.error(e.backtrace.join("\n"))

Definitely test that to make sure it doesn't break the queue though.

[jeremylenz]

So, do you think I should add to the rescue here instead of the upgrade rake task?

Either way, can this be addressed in a followup issue?

[jturel]

I think the rescue & ensure that are there will handle the situation already - but that needs a confirmation - definitely outside of the scope here!

[jeremylenz]

@parthaa Updated route overrides 👍

[jturel]

LGTM ;)

[jeremylenz]

Waiting until theforeman/forklift#1695 is merged.

[jeremylenz]

[test katello]