Fission meets OpenTelemetry (#2157)

* add opentracing section and otelCollectorEndpoint
* initialize OTLP exporter
* pkg/controller: changes for context propagation
* pkg/executor: changes for context propagation
* pkg/fetcher: changes for context propagation
* pkg/router: changes for context propagation
* pkg/storagesvc: changes for context propagation
* set no default value for otel collector endpoint
* update readme and add notes to charts
* move common code to pkg/utils/otel
* adding fn and env as attributes
* don't use otelhttp transport for websocket
* URL ignore with common filter UrlsToIgnore

Note: The web socket example does not work when using OTEL HTTP. Here is an issue related to that on open-telemetry/opentelemetry-js-contrib.

Signed-off-by: Gaurav Gahlot <gauravgahlot0107@gmail.com>
Co-authored-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/executor/executor.go

@@ -255,7 +255,7 @@ func serveMetric(logger *zap.Logger) {
 
 // StartExecutor Starts executor and the executor components such as Poolmgr,
 // deploymgr and potential future executor types
-func StartExecutor(logger *zap.Logger, functionNamespace string, envBuilderNamespace string, port int) error {
+func StartExecutor(logger *zap.Logger, functionNamespace string, envBuilderNamespace string, port int, openTracingEnabled bool) error {
 	fissionClient, kubernetesClient, _, metricsClient, err := crd.MakeFissionClient()
 	if err != nil {
 		return errors.Wrap(err, "failed to get kubernetes client")
@@ -345,7 +345,7 @@ func StartExecutor(logger *zap.Logger, functionNamespace string, envBuilderNames
 	}
 
 	go reaper.CleanupRoleBindings(logger, kubernetesClient, fissionClient, functionNamespace, envBuilderNamespace, time.Minute*30)
-	go api.Serve(port)
+	go api.Serve(port, openTracingEnabled)
 	go serveMetric(logger)
 
 	return nil