How to globally set Attributes for ALL Spans ?

[bmistry13]

I have a use case where I would like to tag all spans with user session (session_uuid). This will act as TAG for all span. When I search in zipkin, by span attributes, I will search for all spans that have session-id == 'some_session_id'.

Is there a thread-local that can be set per-thread for the span that will automatically set attributes?

[iNikem]

One option is to provide your own SpanProcessor.

[HaloFour]

It's a shame SimpleSpanProcessor is final, otherwise it would be trivial to derive from it and override isStartRequired and onStart to populate some default attributes. Still relatively trivial to write an implementation of SpanProcessor that would delegate to SimpleSpanProcessor.

[iNikem]

You don't need to delegate. Just implement your own SpanProcessor and do whatever you like it. onStart methods in SpanProcessor are totally independent on each other.

[HaloFour]

That's true, you could write a simpler implementation that returns false for isEndRequired and add that to a MultiSpanProcessor as well. At worse you have to stub out some of the required methods you won't use, but a good chunk of them are defaulted.

[bmistry13]

@iNikem, I was looking to use SpanProcessor, but do I need to export it I was looking at SimpleSpanProcessor which has an exporter to send span. Please let me know. is the following sufficient?

 new SpanProcessor(){
            @Override
            public void onStart(Context parentContext, ReadWriteSpan span) {
                MyContext ctx = MyCtxHolder.getCtx();
                if(ctx != null && StringUtils.isNotBlank(ctx.getUiSession())){
                    span.setAttribute("ui_session",ctx.getUiSession());
                }
            }

            @Override
            public boolean isStartRequired() {
                return true;
            }

            @Override
            public void onEnd(ReadableSpan span) {
            }

            @Override
            public boolean isEndRequired() {
                return true;
            }
        }

[iNikem]

Change isEndRequired to return false and everything is good :)

[HaloFour]

Would all of these spans belong to one parent span where you could set the attributes? If so, sounds like it could fall under this request to add inheritable attributes to spans: open-telemetry/opentelemetry-specification#1337

[bmistry13]

This is the correct span attribute (session_uuid) that should be inheritable across all children's spans. It is like tagging all spans with session_uuid so can find all spans with session_uuid for a user session. That is the goal.

[bmistry13]

Hi All,

I have spring-slueth and open telemetry library, so my question is if I register SpanProcessor, will both Java Agent and Spring-sleuth (which depends on Open telemetry lib), will both will have setup attribute. I am a newbie to open telemetry so I have few questions:

1. Does register one SpanProcessor will all Tracers will use it ?

Example

2. From the above example, I would have the first register in my main method in the Spring-boot application before any tracer is created?

Again, I am new to Open telemetry and trying to understand SpanProcessor.