Go Function SDK Feature Parity

[flowchartsman]

The Pulsar functions for Go SDK needs some love. It is lacking in some key features and has a couple of rough edges. Broadly, I think the SDK has been held back a little bit from trying to be too much like the Java version, which has resulted in a couple awkward abstractions such as the runtime function deflection dispatch and NewOuputMessage().

This discussion serves to track interest and hopefully chart a way forward.

• State support
  • [Go Function API] Ability to store state #5138
  • [Go Functions] support state storage API #10560
  • Add bookkeeper protocol file for repo bookkeeper#2750 - Abandoned?
  • Reference implementation with usage
• Better multi-topic dispatch
  • [Go Functions] NewOutputMessage API should probably be changed to Publish() #9512
  • [Go Functions] NewOutputMessage does not cache producers #9511
• Secrets Provider
  • [pulsar-function-go]add secrets provider for golang function #8425 (stalled/abandoned)
• Pre-function init
• Depencency-free logging
• Type-safe function signatures

[flowchartsman]

Please comment with any other issues you feel like you need to track, and they can be added to the master list above.

[flowchartsman]

Pre-function init

Most things available from the function context such as tenant, namespace, etc should be available without needing the function context. This exists for user config, and should exist for secrets at the very least.

Logging should also be available as soon as possible, instead of after the function is started.

[flowchartsman]

Depencency-free logging

A new standard, leveling logger will likely be landing in the standard library in the next few versions. Switching to this will provide a more idiomatic logging interface and remove the dependency on logrus.