fix: add basic validation in otlphttpexporter

[anupamdalmia10]

Description: <Describe what has changed.
Adding basic validation to check if at least one endpoint is specified in otlphttpexporter configuration

Link to tracking Issue:
Closes #4709

Testing: < Describe what testing was performed and which tests were added.>
Tested with no endpoints specified and at least one endpoint specified.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Anupam Dalmia (19df779)

[bogdandrutu]

Strange to check for error and not nil.

Should we have also a successful test?

[anupamdalmia10]

Right, that does look inappropriate.
To incorporate test case for the changes, shall we split up the config.yaml in testdata with one file containing blank otlphttpexporter configuration and the other containing the config as in current config.yaml's otlphttp/2?

[bogdandrutu]

I think is ok to have 2 files one ok and one with an error.

[anupamdalmia10]

I have split up the config into good and bad config files and updated the test code accordingly.

[codeboten]

The settings for otlphttp exporters are validated here:

opentelemetry-collector/exporter/otlphttpexporter/factory.go

Lines 63 to 76 in 8399098

	func composeSignalURL(oCfg *Config, signalOverrideURL string, signalName string) (string, error) {
	switch {
	case signalOverrideURL != "":
	_, err := url.Parse(signalOverrideURL)
	if err != nil {
	return "", fmt.Errorf("%s_endpoint must be a valid URL", signalName)
	}
	return signalOverrideURL, nil
	case oCfg.Endpoint == "":
	return "", fmt.Errorf("either endpoint or %s_endpoint must be specified", signalName)
	default:
	return oCfg.Endpoint + "/v1/" + signalName, nil
	}
	}

Is the idea to remove that validation as part of this change?

[codecov]

Codecov Report

Merging #4860 (1c561bf) into main (26e62ce) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #4860   +/-   ##
=======================================
  Coverage   90.60%   90.60%           
=======================================
  Files         180      180           
  Lines       10622    10625    +3     
=======================================
+ Hits         9624     9627    +3     
  Misses        779      779           
  Partials      219      219           

Impacted Files	Coverage Δ
exporter/otlphttpexporter/config.go	100.00% <100.00%> (ø)

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[bogdandrutu]

@codeboten you cannot remove that, since during validation (at least for the moment) we don't have access to the information about what type of component the factory will produce.

The benefit of having the validation sooner than "start" is because we can implement things like "--dry-run" to check for config (or most of the config, as much as we can).

[anupamdalmia10]

@bogdandrutu / @codeboten Is this good to merge?