Add Excon instrumentation

[frederikspang]

Description

Describe your changes:
Adds instrumentation for https://github.com/excon/excon using Excon's Middleware model.

I wanted badly to use with_child_span, however, that seems impossible with the current middleware implementation for Excon.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.17%. Comparing base (b31f0f3) to head (fee8a88).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2383      +/-   ##
==========================================
+ Coverage   98.13%   98.17%   +0.04%     
==========================================
  Files         126      128       +2     
  Lines        4767     4825      +58     
==========================================
+ Hits         4678     4737      +59     
+ Misses         89       88       -1     

Components	Coverage Δ
sentry-ruby	98.56% <100.00%> (+0.05%)	⬆️
sentry-rails	97.08% <ø> (ø)
sentry-sidekiq	96.96% <ø> (ø)
sentry-resque	92.85% <ø> (ø)
sentry-delayed_job	95.65% <ø> (ø)
sentry-opentelemetry	99.31% <ø> (ø)

Files with missing lines	Coverage Δ
sentry-ruby/lib/sentry-ruby.rb	100.00% <100.00%> (+0.45%)	⬆️
sentry-ruby/lib/sentry/excon.rb	100.00% <100.00%> (ø)
sentry-ruby/lib/sentry/excon/middleware.rb	100.00% <100.00%> (ø)
sentry-ruby/lib/sentry/utils/http_tracing.rb	100.00% <100.00%> (ø)

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• Flaky Tests Detection - Detect and resolve failed and flaky tests
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[solnic]

Thank you! This is looking good.

[solnic]

@frederikspang hmm seems like these failures are legit:

1) Sentry::Excon with tracing enabled with config.send_default_pii = true records the request's span with query string in data
     Failure/Error:
       expect(request_span.data).to eq({
         "http.response.status_code" => 200,
         "url" => "http://example.com/path",
         "http.request.method" => "GET",
         "http.query" => "foo=bar"
       })
     
       expected: {"http.query"=>"foo=bar", "http.request.method"=>"GET", "http.response.status_code"=>200, "url"=>"http://example.com/path"}
            got: {"http.query"=>{"foo"=>"bar"}, "http.request.method"=>"GET", "http.response.status_code"=>200, "url"=>"http://example.com/path"}
     
       (compared using ==)
     
       Diff:
       @@ -1,4 +1,4 @@
       -"http.query" => "foo=bar",
       +"http.query" => {"foo"=>"bar"},
        "http.request.method" => "GET",
        "http.response.status_code" => 200,
        "url" => "http://example.com/path",
       
     # ./spec/sentry/excon_spec.rb:84:in `block (4 levels) in <top (required)>'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:124:in `block in run'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:110:in `run'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec_ext/rspec_ext.rb:12:in `run_with_retry'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:37:in `block (2 levels) in setup'

  2) Sentry::Excon with tracing enabled with config.send_default_pii = true records breadcrumbs
     Failure/Error: expect(crumb.data[:query]).to eq("foo=bar")
     
       expected: "foo=bar"
            got: {"foo"=>"bar"}
     
       (compared using ==)
     
       Diff:
       @@ -1 +1 @@
       -"foo=bar"
       +"foo" => "bar",
       
     # ./spec/sentry/excon_spec.rb:108:in `block (4 levels) in <top (required)>'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:124:in `block in run'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:110:in `run'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec_ext/rspec_ext.rb:12:in `run_with_retry'
     # /usr/local/rvm/gems/default/gems/rspec-retry-0.6.2/lib/rspec/retry.rb:37:in `block (2 levels) in setup'

Finished in 10.32 seconds (files took 1.12 seconds to load)
1069 examples, 2 failures, 1 pending

Failed examples:

rspec ./spec/sentry/excon_spec.rb:66 # Sentry::Excon with tracing enabled with config.send_default_pii = true records the request's span with query string in data
rspec ./spec/sentry/excon_spec.rb:92 # Sentry::Excon with tracing enabled with config.send_default_pii = true records breadcrumbs

this is under newer Rubies

[frederikspang]

@solnic I'm thinking this may relate to excon 1.0.0 released JUST the other day.

We've had some specs failing internally as well, post upgrade.
Like when using webmock, Host header had port before, and not after 1.0.0 release.

I'll look into this for the specs!

EDIT: Seems to be rate limit on Docker Hub right now. I'll retry tomorrow.
MIT License in Rack lets us borrow the query builder.

If I'm reading Data Model right in SDK Dev guide, data has to be one dimensional dictionary, so for :query, we'll just build it as a query-string. (And we cannot use .to_query from ActiveSupport :)

[frederikspang]

@solnic A few seemingly unrelated failures as far as I can tell.
Coverage should be improved to 100% patch as well.

[frederikspang]

@solnic Re-review? :)

[solnic]

@frederikspang thanks! I re-tested it on top of latest master and guess what, it still works and looks good :) One last part before I can merge this in is to update this branch to latest master once more so that we can get a green build, and then I'll merge this in!

[frederikspang]

@solnic All good!