Project-10: Remove ConfigurationCacheService (global-zk + local-zk) cache with Metadata-store API

[rdhabalia]

Goal

ConfigurationCacheService keeps local-zk-cache and global-zk-cache which is used by multiple components eg: Broker, Proxy, Discovery-service, WebSocket, etc. #9586 introduced ConfigurationMetadataCacheService which is an alternative of ConfigurationCacheService and it uses Pulsar meadata-store resources,. So, replace ConfigurationCacheService with ConfigurationMetadataCacheService.

Reference

Component: ConfigurationCacheService
Affected Modules: Broker, Websocket, Discovery, Proxy

Notes

1. Replace all references of ConfigurationCacheService with ConfigurationMetadataCacheService across all pulsar components
2. Remove ConfigurationCacheService class

[eolivelli]

I am picking this up

[eolivelli]

@rdhabalia I see that basically ConfigurationMetadataCacheService is only a subclass of ConfigurationCacheService that owns a PulsarResources.
But it is not possible to implement all methods.

I am thinking about using ConfigurationMetadataCacheService#pulsarResources and implement into PulsarResources all of the missing resource types.

I wonder if there is a need to have a ConfigurationMetadataCacheService class at all, we could use directly PulsarResources

Correct ?

[rdhabalia]

The only issue in removing ConfigurationCacheService is it's used by AuthorizationProvider::initialize and part of the contract. We can deprecate it and eventually remove it.
However, PulsarAuthorizationProvider already uses ConfigurationMetadataCacheService now. So, yes, we can replace PulsarResources with ConfigurationCacheService at other places.

I wonder if there is a need to have a ConfigurationMetadataCacheService class at all, we could use directly PulsarResources

yes. We can directly use PulsarResources where ConfigurationCacheService is not part of the contract.

[eolivelli]

@rdhabalia @merlimat
I did not make progress on this work, as I am busy with other priorities.

I can move forward but not in time for 2.8 release