Tasks of removed types cause script errors

[gmmorris]

If a task type definition is removed from kibana, old tasks of that type cause a script error as our painless script throws a null pointer exception when looking for their maxAttempts value in the taskMaxAttempts map.

This change was introduced in 7.11.0 we should fix this before this version is released.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[ymao1]

Draft PR here: #84273

I added unit tests but wasn't sure how to add a functional test for this. Since the task manager doesn't allow for removal of registered types, I would have to start the task manager, register a set of tasks, schedule some tasks, then restart task manager with one of the task types removed to recreate the issue. Is that possible? Or is there a simpler way of doing that?

@gmmorris

[gmmorris]

Draft PR here: #84273

I added unit tests but wasn't sure how to add a functional test for this. Since the task manager doesn't allow for removal of registered types, I would have to start the task manager, register a set of tasks, schedule some tasks, then restart task manager with one of the task types removed to recreate the issue. Is that possible? Or is there a simpler way of doing that?

@gmmorris

It might be that testing this on the current testing framework isn't worth the investment (we've encountered this before).
The one idea I have is to possibly use esArchiver to load a task type that Kibana doesn't know. You don't actually need it to be an old type that doesn't exist anymore, it can be any type that Kibana isn't aware of (I think 🤔 )