feat(excon)! Add a connect span to excon and add more span attributes to the tracer middleware

[misalcedo]

Added a span for TLS and TCP socket connections that matches the one in net_http. Also, I switched to using semantic convention constants over hard-coded strings where applicable. Lastly, I added a few more attributes to the request span.

The untraced_hosts option was added to mirror net_http and allow for selective exclusion of instrumentation.

The attributes before were: http.host, http.method, http.scheme, http.target and peer.service. I added peer name and port as those were also included in net_http.

Testing

The tests are based off the ones found in the net_http instrumentation for the connect span. In writing the tests I found 2 things worth calling out:

• When disabling mocking, WebMock creates an extra span because it creates a new connection with a non-mocked middleware chain.
• Excon does not handle TLS proxies properly in that is still uses plaintext TCP on a TLS proxy because the scheme is based purely on the end host.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: misalcedo / name: Miguel D. Salcedo (ad99f5a, 997d5cd, b399dd8, 9c4e787, 854125b, 8c8eabc, 175818c, 6415ba8, 441f1d0, 55bf3f9, 4bf5b3d, 99d8c62, fd148ef, d6f6c2b, 2cdce0b, d1aa1d4, e3fde0c, 2fbc8e9, 1721eea, c0a2404, 64ec771, 64011e8, 9fb3072, 802100f)
• ✅ login: arielvalentin / name: Ariel Valentin (a0b428d, 851aa89, 1b9c62d)

[kaylareopelle]

Hi @misalcedo, the excon suite is raising some rubocop offenses:

Offenses:

lib/opentelemetry/instrumentation/excon/middlewares/tracer_middleware.rb:50:1: C: [Correctable] Layout/TrailingWhitespace: Trailing whitespace detected.
lib/opentelemetry/instrumentation/excon/patches/socket.rb:16:13: C: [Correctable] Style/IfUnlessModifier: Favor modifier if usage when having a single-line body. Another good alternative is the usage of control flow &&/||.
            if untraced?
            ^^
test/opentelemetry/instrumentation/excon/instrumentation_test.rb:277:33: C: [Correctable] Style/StringLiterals: Prefer single-quoted strings when you don't need string interpolation or special symbols.
      assert_http_spans(scheme: "https")
                                ^^^^^^^

[arielvalentin]

@misalcedo check out this PR which has identified another use case where untraced? should be taken into consideration: https://github.com/open-telemetry/opentelemetry-ruby-contrib/pull/722/files

[misalcedo]

@kaylareopelle thanks for the tip, I addressed the rubocop lints.

[arielvalentin]

Thanks for this contribution 🎉

I have a few nits in there but otherwise LGTM!

[arielvalentin]

@misalcedo we added the rubcop-performance linters on main and now there is a conflict sorry 😿

[misalcedo]

@arielvalentin I addressed the merge conflict. Seems like I just needed to change .include? to .cover? for the status range chack.