Verify and update OTLP trace exporter documentation

[Submarinee]

Partially resolved issue #2016 .
I referred to changes related to OTLP trace exporter in #1827,#1832,#1922, #1963,#1985,#1991, #2013 and created a README about the changes.
BecauseI am a freshman in opentelemetry-go, maybe my PR is not good enough.
If you think I can improve in any aspect, please bring it up.
I am very willing to listen to your suggestions.
Thank u~

I will continue to inventory the documentation for OTLP metric exporter.

• Inventory the documentation for OTLP metric exporter.

[pellared]

nice progress 👍

[pellared]

We miss information about configuration via environmental variables. I am not sure which are supported (you would need to check the code/godoc/changelog). Here are the docs for the env vars that in theory should be supported: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md.

Here is a README how the env vars are documented for Jaeger exporter: https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/jaeger/README.md#environment-variables

[pellared]

I hope this will help you;

opentelemetry-go/exporters/otlp/otlptrace/internal/otlpconfig/envconfig.go

Lines 70 to 137 in d5d4c87

	func (e *EnvOptionsReader) GetOptionsFromEnv() []GenericOption {
	var opts []GenericOption
	// Endpoint
	if v, ok := e.getEnvValue("ENDPOINT"); ok {
	if isInsecureEndpoint(v) {
	opts = append(opts, WithInsecure())
	} else {
	opts = append(opts, WithSecure())
	}
	opts = append(opts, WithEndpoint(trimSchema(v)))
	}
	if v, ok := e.getEnvValue("TRACES_ENDPOINT"); ok {
	if isInsecureEndpoint(v) {
	opts = append(opts, WithInsecure())
	} else {
	opts = append(opts, WithSecure())
	}
	opts = append(opts, WithEndpoint(trimSchema(v)))
	}
	// Certificate File
	if path, ok := e.getEnvValue("CERTIFICATE"); ok {
	if tls, err := e.readTLSConfig(path); err == nil {
	opts = append(opts, WithTLSClientConfig(tls))
	} else {
	otel.Handle(fmt.Errorf("failed to configure otlp exporter certificate '%s': %w", path, err))
	}
	}
	if path, ok := e.getEnvValue("TRACES_CERTIFICATE"); ok {
	if tls, err := e.readTLSConfig(path); err == nil {
	opts = append(opts, WithTLSClientConfig(tls))
	} else {
	otel.Handle(fmt.Errorf("failed to configure otlp traces exporter certificate '%s': %w", path, err))
	}
	}
	// Headers
	if h, ok := e.getEnvValue("HEADERS"); ok {
	opts = append(opts, WithHeaders(stringToHeader(h)))
	}
	if h, ok := e.getEnvValue("TRACES_HEADERS"); ok {
	opts = append(opts, WithHeaders(stringToHeader(h)))
	}
	// Compression
	if c, ok := e.getEnvValue("COMPRESSION"); ok {
	opts = append(opts, WithCompression(stringToCompression(c)))
	}
	if c, ok := e.getEnvValue("TRACES_COMPRESSION"); ok {
	opts = append(opts, WithCompression(stringToCompression(c)))
	}
	// Timeout
	if t, ok := e.getEnvValue("TIMEOUT"); ok {
	if d, err := strconv.Atoi(t); err == nil {
	opts = append(opts, WithTimeout(time.Duration(d)*time.Millisecond))
	}
	}
	if t, ok := e.getEnvValue("TRACES_TIMEOUT"); ok {
	if d, err := strconv.Atoi(t); err == nil {
	opts = append(opts, WithTimeout(time.Duration(d)*time.Millisecond))
	}
	}
	return opts
	}

[MrAlias]

@pellared can you add this in a follow on PR?

[pellared]

@MrAlias Added to my TODO list. I will try to do it next week.

[MrAlias]

@MrAlias Added to my TODO list. I will try to do it next week.

🎉 thanks 😄

[pellared]

PR: #2222

[MrAlias]

This looks like an incremental improvement to the docs. Thanks for the contribution.

The suggestions are not blocking.

[MrAlias]

This is the last PR blocking our next RC release. I'm going to see if I can push some code to move this along.

[MrAlias]

@dashpole @pellared please take another look.