Print final configuration

[pavolloffay]

Is your feature request related to a problem? Please describe.

When running the collector I don't know what configuration is being used. For instance when the collector is run with the following config I don't know what is the batching, qretry or OTLP receiver configuration. To find out these details I have to read the docs.

receivers:
    otlp:
        protocols:
            grpc:

exporters:
    logging:
        logLevel: debug

processors:
    batch:
    queued_retry:

service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: [batch, queued_retry]
      exporters: [logging]

Describe the solution you'd like

I can think of two possible solutions:

1. Print each component config when the component is starting
2. Add a flag that prints full configuration to stdout

Describe alternatives you've considered
None

Additional context
jaegertracing/jaeger#2253

[pavolloffay]

@tigrannajaryan @bogdandrutu any comments? I could work on this.

[tigrannajaryan]

This would be very useful.

I think this is a good approach:

Add a flag that prints full configuration to stdout

[bogdandrutu]

@pavolloffay I would look into hooking this in the service z-pages so user can have access to this without looking into logs. See https://github.com/open-telemetry/opentelemetry-collector/blob/master/service/service.go#L511 and https://github.com/open-telemetry/opentelemetry-collector/blob/master/service/service.go#L526

[yurishkuro]

This WIP may address this open-telemetry/opentelemetry-collector-contrib#27003

[mx-psi]

I am going to close this as a duplicate of #5223, since this one has more specific discussion about removing sensitive fields and about the general design