Description:

 It has been advised in OSSM docs to include the namespace containing OpenTelemetryCollector in ServiceMeshMemberRoll.

I cam across a situation where end users tend to keep TempoStack and OpenTelemetryCollector in same namespace and they added the namespace in SMMR resource as well. Because of this, querying of traces returns timeout because all of the traffic is denied by default. 

It would be better to have a section of documentation to allow connections from openshift-cluster-observability-operator as DistributedTracing UIPlugin runs in that namespace. Below NetworkPolicy needs to be created to fix the same:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-openshift-observability-operator
  namespace: tracing-system  // Namespace containing tempostack and otelcol
spec:
  podSelector: {}
  policyTypes:
    - Ingress
  ingress:
    - from:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: openshift-cluster-observability-operator 

Documentation:

 [-]https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html-single/service_mesh/index#ossm-overview-distr-tracing_observability