Sampling only Remote Traces

[renaz6]

• By default, local traces are not sampled
• Configuration added so that local tracing can be turned on if desired

[renaz6]

Documentation on Parent Based Sampling can be found here:https://pkg.go.dev/go.opentelemetry.io/otel/sdk/trace#ParentBased

[renaz6]

I'm not sure if we should use AlwaysSample() even if sampleLocalTraces is configured to be true. The documentation suggests not using this in production environments that see a lot of traffic, but I also doubt we'll see parent-less traces.
An alternative option is using TraceIDRatioBased() (https://pkg.go.dev/go.opentelemetry.io/otel/sdk/trace#TraceIDRatioBased) and only sending a percentage of traces through.

[schmidtw]

If we split apart the choices a bit more we can let the user decide what they want without us needing to do much & we can expand/grow later.

Replace sampleLocalTraces with:

  sampling-strategy:
    parent-initiated: ignore # [ignore (default), honor]
    no-parent: never         # [never (default), always, traceidratio, ...]
    traceidratio:            # For each sampler that needs inputs they get enumerated separately.
        percentage: 15.5

Choosing the quietest mode (completely off) as defaults.

Until we need to add traceidratio we can just know it goes here. I think @Sachin4403 may want:

  sampling-strategy:
    parent-initiated: honor
    no-parent: always

We'll probably want to use:

  sampling-strategy:
    parent-initiated: honor
    no-parent: never

We can add the traceidratio later if someone wants/needs it.

[renaz6]

Taking care of this in #102

[johnabass]

Given Wes's comment, we can do a separate PR to address the separate choices.

[sonarcloud]

SonarCloud Quality Gate failed.   

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