Jaeger should create a root span for incoming requests with baggage but without a trace. about jaeger-client-go

[blampe]

@yurishkuro any thoughts here?

It seems that we should be able to curl an application without needing an explicit tracing header.

[yurishkuro]

The way I would approach it is similar to jaeger-debug-id, i.e. define a standard header like jaeger-baggage that will copy the baggage into the root span. Some decisions to make about it is the format of the value, e.g.

jaeger-baggage: key=value,key=value,key=value

[vprithvi]

@yurishkuro How do you feel about adopting http query strings ( e.g jaeger-baggage: key1=value1&key2=value%20two) as the header value format instead?
I feel that query strings are relatively more standard, and are understood by more things than the format you suggested.

[yurishkuro]

the comma-separated list is how HTTP defines repeated headers, that is when we iterate through the headers we might get the same header repeated, or the value can be a comma-separated list. So that leaves just the question of key=value separation, which is the same in both representations.

[vprithvi]

I see, I wasn't aware of that.
Another option is doing something similar to how we inject headers for propagation, i.e having a header value prefix

jaeger-baggage-key1: value1
jaeger-baggage-key2: value2

[yurishkuro]

I think you're overcomplicating it. I consider sending curl request with baggage to be a very marginal use case to begin with, not to mention doing it with more than one baggage item. Comma-separated string works for that, and actually simpler to use than numbered headers, both for sending and for reading.

[vprithvi]

You are right, let's stick to the original suggestion

[yurishkuro]

Fixed by #49, released as 1.6