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>

charts/fission-core/templates/router.yaml

@@ -55,8 +55,12 @@ spec:
             value: {{ .Values.router.svcAddressUpdateTimeout | default "30s" | quote }}
           - name: ROUTER_UNTAP_SERVICE_TIMEOUT
             value: {{ .Values.router.unTapServiceTimeout | default "3600s" | quote }}
+          - name: OTEL_COLLECTOR_ENDPOINT
+            value: "{{ .Values.otelCollectorEndpoint }}"
+          - name: OPENTRACING_ENABLED
+            value: {{ .Values.openTracing.enabled | default false | quote }}
           - name: TRACE_JAEGER_COLLECTOR_ENDPOINT
-            value: "{{ .Values.traceCollectorEndpoint }}"
+            value: "{{ .Values.openTracing.collectorEndpoint }}"
           - name: TRACING_SAMPLING_RATE
             value: {{ .Values.router.traceSamplingRate | default "0.5" | quote }}
           - name: USE_ENCODED_PATH