handle OTEL_EXPORTER_OTLP_TRACES and fix unix endpoints (#100)

* handle OTEL_EXPORTER_OTLP_TRACES env variables

Defined in https://github.com/open-telemetry/opentelemetry-specification/blob/v1.8.0/specification/protocol/exporter.md

These variables are defined more specifically
so take priority over the generic vars if set.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

* fix handling of unix URLs

Unix URLs should not need any special handling but
current implementation handles values without the
schema that is not allowed by the spec.

If this can be removed in the future then all these
exceptions can be removed as well and WithInsecure
is automatically detected by the endpoint value
in otlptracegrpc package.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

otelcli/plumbing.go

@@ -34,7 +34,7 @@ func grpcOptions() []otlpgrpc.Option {
 	// an obvious "localhost", "127.0.0.x", or "::1" address.
 	if config.Insecure || isLoopbackAddr(config.Endpoint) {
 		grpcOpts = append(grpcOpts, otlpgrpc.WithInsecure())
-	} else {
+	} else if !isInsecureSchema(config.Endpoint) {
 		var tlsConfig *tls.Config
 		if config.NoTlsVerify {
 			tlsConfig = &tls.Config{
@@ -95,7 +95,7 @@ func httpOptions() []otlphttp.Option {
 	// "127.0.0.x", or "::1" address.
 	if config.Insecure || isLoopbackAddr(config.Endpoint) {
 		httpOpts = append(httpOpts, otlphttp.WithInsecure())
-	} else {
+	} else if !isInsecureSchema(config.Endpoint) {
 		var tlsConfig *tls.Config
 		if config.NoTlsVerify {
 			tlsConfig = &tls.Config{
@@ -203,6 +203,8 @@ func isLoopbackAddr(endpoint string) bool {
 			softFail("error parsing provided URI '%s': %s", endpoint, err)
 		}
 		hostname = u.Hostname()
+	} else if strings.HasPrefix(endpoint, "unix://") {
+		return false
 	} else {
 		softFail("'%s' is not a valid endpoint, must be host:port or a URI", endpoint)
 	}
@@ -224,3 +226,9 @@ func isLoopbackAddr(endpoint string) bool {
 	diagnostics.DetectedLocalhost = allAreLoopback
 	return allAreLoopback
 }
+
+// isInsecureSchema returns true if the provided endpoint is an unencrypted HTTP URL or unix socket
+func isInsecureSchema(endpoint string) bool {
+	return strings.HasPrefix(endpoint, "http://") ||
+		strings.HasPrefix(endpoint, "unix://")
+}

otelcli/root.go

@@ -51,6 +51,12 @@ func addCommonParams(cmd *cobra.Command) {
 		"timeout":  "OTEL_EXPORTER_OTLP_TIMEOUT",
 		"verbose":  "OTEL_CLI_VERBOSE",
 	}
+	if _, ok := os.LookupEnv("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT"); ok {
+		common_env_flags["endpoint"] = "OTEL_EXPORTER_OTLP_TRACES_ENDPOINT"
+	}
+	if _, ok := os.LookupEnv("OTEL_EXPORTER_OTLP_TRACES_TIMEOUT"); ok {
+		common_env_flags["timeout"] = "OTEL_EXPORTER_OTLP_TRACES_TIMEOUT"
+	}
 
 	for config_key, env_value := range common_env_flags {
 		viper.BindPFlag(config_key, cmd.Flags().Lookup(config_key))