profiler: Implement WithUploadTimeout

[felixge]

Also add support for the DD_PROFILING_UPLOAD_TIMEOUT used by other
DD profilers such as Java.

The timeout is implemented using a request context, which allows
removing the timeout option from the defaultClient and WithUDS option.

defaultHTTPTimeout is promoted to DefaultUploadTimeout to be consistent
with the other default options.

The order of preference is:

1. DefaultUploadTimeout
2. DD_PROFILING_UPLOAD_TIMEOUT
3. WithUploadTimeout()

Implements PROF-2810

[pmbauer]

This is an objectively better approach than the existing pattern. Until recently there was no specified upload timeout; the state of code prior to this pull request was modeled on what dd-trace-go/ddtrace is doing.

• dd-trace-go/ddtrace/tracer/option.go

  Line 360 in 4451a5c

  Timeout: defaultHTTPTimeout,

• dd-trace-go/ddtrace/tracer/option.go

  Line 379 in 4451a5c

  Timeout: defaultHTTPTimeout,

• dd-trace-go/ddtrace/tracer/transport.go

  Line 45 in 4451a5c

  Timeout: defaultHTTPTimeout,

However, I do think there should be a default timeout, which this pull request effectively removes.

We might also add a test for this in upload_test.go.

@gbbr thoughts on this approach and updating the trace client to use a similar pattern?

[pmbauer]

Nevermind, I can't read. I do see the DefaultUploadTimeout

[gbbr]

@gbbr thoughts on this approach and updating the trace client to use a similar pattern?

I guess users can currently change the default client to a custom http.Client to obtain this effect. Is that different than a request with a timeout context? Not sure.

There was no need to have this until now with a specific function, but we can if we have to.

[pmbauer]

@gbbr that makes sense. Profiler has a DD_PROFILING_UPLOAD_TIMEOUT env var we are trying to normalize our clients on and as the tracer doesn't have an equivalent, it makes sense to deviate here I think.

[felixge]

@gbbr @pmbauer this is ready for another look, thx!