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/router/util/util.go

@@ -17,6 +17,8 @@ limitations under the License.
 package util
 
 import (
+	"net/http"
+
 	v1 "k8s.io/api/networking/v1"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -100,3 +102,8 @@ func GetDeployLabels(trigger *fv1.HTTPTrigger) map[string]string {
 		"triggerNamespace": trigger.ObjectMeta.Namespace,
 	}
 }
+
+func IsWebsocketRequest(request *http.Request) bool {
+	return request.Header.Get("Upgrade") == "websocket" &&
+		request.Header.Get("Connection") == "Upgrade"
+}