issue in httplib and requests

The following code would generate 5 spans, which seems to be confusing:

import requests
from opencensus.trace import config_integration
from opencensus.trace.tracer import Tracer
config_integration.trace_integrations(['httplib', 'requests'])
tracer = Tracer()
with tracer.span(name='parent'):
    response = requests.get('https://www.wikipedia.org/wiki/Rabbit')

Expected:

1. Probably we only want 4 spans, need to dig out more:

parent span
    requests span
        httplib span, which returned HTTP 301 (redirection)
        httplib span, which returned HTTP 200

1. The httplib span attribute http.url should be full URL, current it is /wiki/Rabbit.

[SpanData(name='[httplib]request', context=SpanContext(trace_id=56b691b1c448a80bfd21455d1e3916ac, span_id=21a6c4871e00d227, trace_options=TraceOptions(enabled=True), tracestate=None), span_id='b0cd26aa762e72c5', parent_span_id='21a6c4871e00d227', attributes={'http.url': '/wiki/Rabbit', 'http.method': 'GET', 'http.status_code': '301'}, start_time='2019-04-23T00:46:40.566298Z', end_time='2019-04-23T00:46:40.587506Z', child_span_count=0, stack_trace=None, time_events=[], links=[], status=None, same_process_as_parent_span=None, span_kind=2)]
[SpanData(name='[httplib]request', context=SpanContext(trace_id=56b691b1c448a80bfd21455d1e3916ac, span_id=21a6c4871e00d227, trace_options=TraceOptions(enabled=True), tracestate=None), span_id='9099cb62a56c5910', parent_span_id='21a6c4871e00d227', attributes={'http.url': '/wiki/Rabbit', 'http.method': 'GET', 'http.status_code': '200'}, start_time='2019-04-23T00:46:40.703073Z', end_time='2019-04-23T00:46:40.718689Z', child_span_count=0, stack_trace=None, time_events=[], links=[], status=None, same_process_as_parent_span=None, span_kind=2)]
[SpanData(name='[requests]get', context=SpanContext(trace_id=56b691b1c448a80bfd21455d1e3916ac, span_id=f240885e8fcd8866, trace_options=TraceOptions(enabled=True), tracestate=None), span_id='21a6c4871e00d227', parent_span_id='f240885e8fcd8866', attributes={'http.url': 'https://www.wikipedia.org/wiki/Rabbit', 'http.status_code': '200'}, start_time='2019-04-23T00:46:40.433738Z', end_time='2019-04-23T00:46:40.770006Z', child_span_count=0, stack_trace=None, time_events=[], links=[], status=None, same_process_as_parent_span=None, span_kind=2)]
[SpanData(name='[requests]get', context=SpanContext(trace_id=56b691b1c448a80bfd21455d1e3916ac, span_id=f9b3b7a04c993de9, trace_options=TraceOptions(enabled=True), tracestate=None), span_id='f240885e8fcd8866', parent_span_id='f9b3b7a04c993de9', attributes={'http.url': 'https://www.wikipedia.org/wiki/Rabbit', 'http.status_code': '200'}, start_time='2019-04-23T00:46:40.433738Z', end_time='2019-04-23T00:46:40.776972Z', child_span_count=0, stack_trace=None, time_events=[], links=[], status=None, same_process_as_parent_span=None, span_kind=2)]
[SpanData(name='parent', context=SpanContext(trace_id=56b691b1c448a80bfd21455d1e3916ac, span_id=None, trace_options=TraceOptions(enabled=True), tracestate=None), span_id='f9b3b7a04c993de9', parent_span_id=None, attributes={}, start_time='2019-04-23T00:46:40.433738Z', end_time='2019-04-23T00:46:40.778972Z', child_span_count=0, stack_trace=None, time_events=[], links=[], status=None, same_process_as_parent_span=None, span_kind=0)]

[reyang]

@lzchen FYI.

@victoraugustolls Thanks for bringing it up. We haven’t worked on this issue.

Here goes my current thinking:

1. We need to track the actual underlying HTTP operation (which has a strict 1:1 mapping for the actual HTTP outbound request).
2. It would be helpful to track the high level HTTP operation, which is the logical layer thing. For example, if someone is trying to HTTP GET http://non.existing.domain/, we expect the logical operation to fail, with no actual physical HTTP call (since DNS resolution failure will trigger exception on the HTTP client).
3. For metrics, we want to use 1) for the actual HTTP requests/second and latency (as counting invalid DNS or URL for average latency does not make sense). We can use 2) for logical operations, similar like how people would use metrics for local spans.

We can discuss more at https://github.com/open-telemetry/opentelemetry-specification/issues/110.

With this, I would expect the result to be:

parent span
    requests span
        httplib span, which returned HTTP 301 (redirection)
        httplib span, which returned HTTP 200

metrics:
    number of HTTP request: 2
    number of spans from requests library: 1

[lzchen]

@NoutieH If you would like to contribute this part, go for it! I can assign the task to you.