Disable opentelemetry-go based on a flag

[Ajaykumarkolipaka]

Hello Community,
Can someone know best way to tackle this?

I'm following this doc to instrument the code. I want to disable the tracer feature so that there won't be any span creation and exporter tasks will happen.

1. I tried to put alwaysOffSampler, by doing this spans are not getting exported but spans are getting created. How can I disable completely without make any code changes?
2. using NewNoopTracerProvider creats no ops spans, but will it has any performance impact?

[dmathieu]

OpenTelemetry will default all spans creation to noop unless another tracer provider is included.

For example, in the named tracer example, if you don't call the initTracer method, nothing will happen. But your code will keep running exactly the same.
So the best way to disable tracing in your app while keeping the otel code around is to not configure any tracer.

As for performance of the noop provider, the impact should be minimal. You can see how the provider and spans work there: https://github.com/open-telemetry/opentelemetry-go/blob/main/trace/noop.go

[Ajaykumarkolipaka]

Hi @dmathieu, Thanks for your suggestion.
I skipped the call to initTracer method based on enable/disable flag, but i'm running into null pointer exception when i'm making a call to tracer.Start(ctx, spanName) method as the tracer is not initialised. Any suggestions how to fix this?

[dmathieu]

Could you share the full error?

[Ajaykumarkolipaka]

if enableTracer { shutdown := initTracer() defer shutdown() }
_, span := tracer.Start(ctx, "spanName")

Error log:
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x98ca45]

we are not initialising the tracer but other part of the code is trying to create the spans using tracer object. as the tracer object is nil, it's throwing above error.

[dmathieu]

Please include a full stack trace, not just the error.

Even when the tracer isn't configured, you shouldn't get an invalid memory address, unless something is wrong. When not configured, the library defaults to a noop tracer.

As an example, the following code runs properly:

package main

import (
	"context"

	"go.opentelemetry.io/otel"
)

func main() {
	tracer := otel.Tracer("")

	ctx := context.Background()
	ctx, span := tracer.Start(ctx, "test")
	defer span.End()
}

[Ajaykumarkolipaka]

As I want to enable or disable the tracer based on a flag, if configured this way
if the flag is set to false: noop tracer will be initialised and sampling rate will be set to 0.

if I configured in above manner, can I say tracer got disabled? or else will there be any action happening in the background?

[Ajaykumarkolipaka]

I did above configuration and tried to log the traceId and spanId, I'm getting all 0's .
traceId=00000000000000000000000000000000, spanId=0000000000000000

[gmann42]

@Ajaykumarkolipaka Did you manage to solve this ? I am looking for exactly same thing.

[Hannarong98]

a little bit late, but try:

// in func SetupOTelSDK
if(traceEnabled == "false") {
   otel.SetTracerProvider(noop.NewTracerProvider())
} else {
  // use non noop provider
}