[jaeger-v2] Refactor Adaptive Sampling Processor Configurations

[mahadzaryab1]

Requirement

In this issue, we want to refactor the configurations for the adaptive sampling processor to ensure that the configuration is laid out logically (part of #5229)

Tasks / outcomes

• All config fields are tagged with mapstructure such that they can be addressable from YAML via "good" names
• Configs implement Validate()
• Configs via YAML support the same defaults as in jaeger-v1
• Configs reuse standard elements of OTEL configs whenever possible, e.g. TLS, clientcfg, etc.
• Configuration looks "logical" and properly grouped, not flattened with long weird names
• We create a migration guide document with a table that lists v1 CLI flags and the corresponding v2 config fields

[mahadzaryab1]

@yurishkuro Do we need https://github.com/jaegertracing/jaeger/blob/main/cmd/jaeger/internal/processors/adaptivesampling/config.go? It looks to be empty and all the config seems to be in the remote sampling extension?

[yurishkuro]

A config is required by the overall organization of OTEL components, even if it's empty.

There's nothing to align with OTEL here since adaptive sampling is jaeger-only feature, but we can take a critical look how that config is laid out. Also, the extension runs servers, so we can make sure they are using OTEL configs and helpers.

[mahadzaryab1]

@yurishkuro is there a reason that SamplingStore is separate from the rest of the config in https://github.com/jaegertracing/jaeger/blob/main/cmd/jaeger/internal/extension/remotesampling/config.go#L41-L46? Can I move SamplingStore under adaptive.Options?

[yurishkuro]

The reason is because it's not applicable to v1 collector.

[mahadzaryab1]

Does it hurt to combine it? Currently in the config we have something like:

sampling_store:
sampling:
  ...

It would be nice to do something like

sampling:
  store:
  ...

[yurishkuro]

Feel free to propose a change.

Do we use store or storage in query service?

[mahadzaryab1]

@yurishkuro Here is the migration guide for the adaptive sampling processor. Are there any other action items as part of this issue? If not, we can close it out.

[mahadzaryab1]

It was decided that no changes were needed to the configuration. Only the migration guide was created as part of this issue which has been added to the V2 RFC.