Jaeger Receiver Config Fixes

[joe-elliott]

Fixes #445, #158

This PR addresses some Jaeger receiver config cleanup as well as makes some breaking changes to the way the config is handled. See below for details.

Fixes/Updates

• Disabled flag is respected per protocol
• Unspecified protocols will no longer be started
• Empty protocol configs can now be specified to start the protocol with defaults. e.g.

  jaeger:
    protocols:
      grpc:
  

• Updated readmes
• Naming and behavior of per protocol Addr/Enabled functions in trace_reciever.go has been standardized.
• Added thrift tchannel test to meet code coverage

Breaking Change
Changed the way an empty jaeger: config is handled. An empty/default config does not start any jaeger protocols. Previously it started all three collector protocols. This is a consequence of not starting unspecified protocols.

[codecov-io]

Codecov Report

Merging #490 into master will decrease coverage by 0.07%.
The diff coverage is 65.36%.

@@            Coverage Diff             @@
##           master     #490      +/-   ##
==========================================
- Coverage   75.99%   75.91%   -0.08%     
==========================================
  Files         120      119       -1     
  Lines        7415     7437      +22     
==========================================
+ Hits         5635     5646      +11     
- Misses       1514     1522       +8     
- Partials      266      269       +3

Impacted Files	Coverage Δ
receiver/jaegerreceiver/config.go	69.23% <ø> (ø)	⬆️
...er/prometheusreceiver/internal/metrics_adjuster.go	92.81% <ø> (ø)	⬆️
receiver/factory.go	100% <ø> (ø)	⬆️
processor/batchprocessor/node_batcher.go	90.13% <0%> (-1.21%)	⬇️
processor/queuedprocessor/queued_processor.go	45.75% <0%> (-0.61%)	⬇️
exporter/exportertest/sink_exporter.go	69.23% <0%> (ø)	⬆️
processor/spanprocessor/span.go	85.71% <0%> (-4.29%)	⬇️
processor/attributesprocessor/attributes.go	93.25% <0%> (-2.15%)	⬇️
exporter/exportertest/nop_exporter.go	85.18% <0%> (ø)	⬆️
processor/resourceprocessor/resource_processor.go	85.71% <0%> (-6.6%)	⬇️
... and 32 more

---

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[pjanotti]

Hi @joe-elliott, what is the behavior when empty jaeger: is specified? The breaking change is fine as long as that is reported as an error (so it will be clear that the at least one protocol needs to be specified).

[pjanotti]

LGTM @joe-elliott just need to fix the test

--- FAIL: TestLoadConfig (0.01s)
    config_test.go:37: 
        	Error Trace:	config_test.go:37
        	Error:      	Received unexpected error:
        	            	error reading settings for receiver type "jaeger": must specify at least one protocol when using the Jaeger receiver
        	Test:       	TestLoadConfig

[joe-elliott]

@pjanotti Thanks for the comments.

When starting the Jaeger receiver with an unknown protocol the collector will now log:

Cannot load configuration: error reading settings for receiver type "jaeger": unknown jaeger protocol <bad proto>

When starting the Jaeger receiver with no protocols the collector will now log:

Cannot load configuration: error reading settings for receiver type "jaeger": must specify at least one protocol when using the Jaeger receiver

[pjanotti]

Thanks for the PR @joe-elliott LGTM

[joe-elliott]

@tigrannajaryan I believe I have addressed your concerns.

Note that I went ahead and exported GetConfigSection from the config package. It seems like this function will be useful for any future custom unmarshallers as it will allow them to easily reuse all of the environment substitution logic in the config package. If this is not desirable, I will revert and try a different path.

[tigrannajaryan]

Mostly LGTM, only a couple small nits.

[joe-elliott]

@tigrannajaryan I believe that covers it. Let me know if I can make any other changes.

[tigrannajaryan]

LGTM. Thank you.