Provide hooks for vendor-specific customization

[trask]

Some things vendors would like to be able to provide without having to fork this repo:

• ✅Custom configuration story
• Custom logging story
• ✅Custom IdsGenerator
• ✅Custom Resource
• ✅Custom Propagator

[iNikem]

In addition:

• ✅Add new instrumentation
• ✅Override any existing instrumentation
• ✅Add attributes to existing instrumentation's spans

Edit: last two point from above are addressed by #1623

[devinsba]

I would probably say:

• remove/disable (if not covered by config) instrumentation
• customize/intercept attributes on spans

[trask]

Also:

• ✅Custom sampler - Allow configuration of custom sampler #387 (comment)

[RashmiRam]

I am looking for this. @iNikem Do you want me to create a separate issue for this?

In addition:

• Add new instrumentation
• Override any existing instrumentation
• Add attributes to existing instrumentation's spans

[iNikem]

@RashmiRam I am afraid I don’t understand your question

[RashmiRam]

Sorry If I am not being clear. I assumed that the above comment from you & question from me in Gitter https://gitter.im/open-telemetry/opentelemetry-java-instrumentation?at=5efefb93bb149531ede7d726 is similar. Is it not?

[iNikem]

Ah :) If your need is for vendor-specific auto-instrumentation, then indeed this issue seems to cover that. I was under impression that you wanted for an option for manual instrumentation to add attributes to spans created by auto-instrumentation. I think they are somewhat different things.

[RashmiRam]

Yes. You are right. I was specifically looking for an option for manual instrumentation to add attributes to spans created by auto-instrumentation. Can't it be achieved by vendor specific customization too?

[iNikem]

Don't know yet :)

[trask]

hey @RashmiRam, can you give an example that you are trying to solve, e.g. which instrumentation's spans, and what attributes you would like to add to those spans? i agree with @iNikem, i don't think we've thought about this use case yet, so would be great to have a concrete example to think about. thx!

[RashmiRam]

Say, I have a multi-tenant application where each tenant id will be part of the incoming web request url. It would be useful to add the tenant-id as a custom attributes to all the child spans created for the request so that it could be seen if a particular tenant behaves erratically for these type of requests.

Incoming Web request url /api/<tenant-id>/resources is coming to an app using jetty web server.
Server span for this request already contain these following attributes when using auto instrumentation

http.method: "POST"
http.status_code: 204
http.url: "http://127.0.0.1/api/1234/resources"
internal.span.format: "proto"
net.peer.ip: <ip>
net.peer.port: 48458
span.kind: "server"
span.origin.type: "org.eclipse.jetty.server.handler.StatisticsHandler"
status.code: 0

I wanted to add the following attribute(s) to the server span created by auto instrumentation

tenant_id: 1234
some-app-tag:value

This is just an example. But, providing hooks to add dynamic request based custom attributes to spans created using auto instrumentation will be immensely helpful to capture application/business logic information of the traces.

[RashmiRam]

@iNikem I am able to add custom attributes to a currentSpan() programmatically. I have a dropwizard app with few custom ContainerRequestFilter. I have added the following code changes and it seemed to add this custom attributes to jetty server span(as that was the current span while I accessed it in my ContainerRequestFilter).

Span currentSpan = OpenTelemetry.getTracerProvider().get("any-name-it-doesn't-matter").getCurrentSpan();
currentSpan.setAttribute("tenant_id", 1234);

Dependencies:

 compile group: 'io.opentelemetry', name: 'opentelemetry-api', version: '0.6.0'

Is this intended & recommended way of adding our own custom attributes?

[iNikem]

That is a great question. While setting attributes on span seems totally fine, I feel uneasy about your way of getting hold to Tracer instance. @trask can you comment on that?

[RashmiRam]

I am able to add spans to the current context as well.

  Span mySpan = null;
  Tracer tracer = OpenTelemetry.getTracerProvider().get("any-name-it-doesn't-matter");
  Span currentSpan = tracer.getCurrentSpan();
  try(Scope scope = tracer.withSpan(currentSpan)) {
    mySpan = tracer.spanBuilder("Creating my Span").setSpanKind(Span.Kind.INTERNAL).startSpan();    
    mySpan.setAttribute("my_custom_attribute", "This is so cool");
    <<my logic>>
  }
  finally {
    mySpan.end();
    mySpan.setStatus(Status.OK);
  }