Allow configuration of jaeger client in the query service

[black-adder]

Requirement - what kind of business use case are you trying to solve?

The jaeger query service allows for tracing the query service itself. In the all-in-one container, the default initialization of the client works since the agent/collector reside on localhost. However, when the query service is deployed individually, the collector and agent are not guaranteed to be running locally or maybe running on non-default ports depending on the setup.

Problem - what in Jaeger blocks you from solving the requirement?

The query service exposes no flags or environment variables to configure the tracer in the query service.

Proposal - what do you suggest to solve the problem or improve the existing situation?

The golang tracer allows configuration via environment variables. I think all we'd have to do is to replace New with FromEnv.

Any open questions to address

[trtg]

@black-adder is it possible to disable tracing of jaeger-query? It results in a lot of additional traffic to the collectors and to our cassandra backend and looking at tons of "Collector::submitBatches" spans is not very informative.

[jpkrohling]

@trtg , once this issue here is fixed, you should be able to export JAEGER_DISABLED to the Query process and have tracing disabled.

[cosmologist10]

Hi! I want to work on this issue.

[subashiniganesh]

Hello @jpkrohling ,

I am Subashini, an aspiring Outreachy candidate. As I came to know about outreachy very recently, do you still have space for new applicants? May I still attempt solving issues?

@cosmologist10, If you're caught up doing something else, May I work on this issue?

Thanks.

[jpkrohling]

Sorry for the late response, @subashiniganesh, but I was out last week. You are certainly welcome to submit a patch by the program's deadline, which happens to be tomorrow. It's a tight deadline, but might be doable if you are experienced in Golang.

[subashiniganesh]

Ah!! Thanks for such a positive note @jpkrohling . I submitted a PR. It was such an exciting experience. Shall I make an application and continue contributing?

[jpkrohling]

Sure, but hurry, it might be closing soon (if it's not closed already)!!!

[subashiniganesh]

Thanks @jpkrohling . I submitted the final application. And I am so glad to note that until Nov 16, we are allowed to make and record code contributions. Let me please search and find an issue and continue contributing. Please let me know if you have any suggestions.