Avoid infinity loop when exporter use http to send spans

[OlivierAlbertini]

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

Right now, I must use this config to avoid infinity loop:

const config = { 
 plugins: {
            http: {
                enabled: true,
                path: '@opentelemetry/plugin-http',
                ignoreOutgoingUrls: [/spans/]
            }
        }
}

Describe the solution you'd like
We should handle this internally. Perhaps we could use a specific header that will be handled by http plugin for ignoring outgoing request with that header?

[vmarchaud]

We have a specific header with Opencensus to avoid this issue: https://github.com/census-instrumentation/opencensus-node/blob/master/packages/opencensus-instrumentation-http/src/http.ts#L46

[OlivierAlbertini]

should we set x-opentelemetry-outgoing-request ?

[vmarchaud]

@OlivierAlbertini i'm good with the header you set in the PR

[ljcremer]

This still seems to be an issue and caused our platform to log 50M+ spans in two weeks with very little traffic on the platform.
Here is the related issue and the way we resolved it:

[dyladan]

@ljcremer we are working on a new way to prevent these infinite loops by allowing exporters to set a context property during export which disables tracing. A quick glance at the exporter code looks like the header to disable tracing is set properly in the exporter, but I'll make sure the http/https plugins are properly respecting it.

[aabmass]

@dyladan Looks like the Python SDK actually sets the context before the exporter is run, which is nice because the exporters don't need to do anything.

https://github.com/open-telemetry/opentelemetry-python/blob/672a89c7c6b2b302216cfdeb05b4105ca8db67c6/opentelemetry-sdk/src/opentelemetry/sdk/metrics/export/controller.py#L59-L61

It does the same in the SpanProcessors for traces:
https://github.com/open-telemetry/opentelemetry-python/blob/b085f376e0b0bd1c76e8ff4e3f09e995927f7311/opentelemetry-sdk/src/opentelemetry/sdk/trace/export/__init__.py#L204

[dyladan]

Yes I meant span processor. I often say "Exporter" to refer to the whole export pipeline or process.

[Hariharan-Neutrinos]

what is the solution for this? Fix!?

[Flarna]

current solution is that SpanProcessor/exporter set the suppressTracing marker on context which causes that tracer doesn't create a span.
see e.g. here, here and here.

There might be other implementations of Exporters/SpanProcessors/Tracers in the wild which are not covered by the SDK implementation so they should adapt this approach.