Add OpenTracing configurability

[miguelsorianod]

This exposes OpenTracing functionality provided by APIcast into the APIcast operator.

Design

A new spec.openTracing section has been added in the APIcast CR.

An example:

spec:
  openTracing:
    enabled: true
    tracingLibrary: jaeger
    tracingConfigRef:
      name: mysecretname

• All attributes in the openTracing section are optional
• If the enabled flag is not specified, it defaults to false
• If the tracingLibrary flag is not specified, it defaults to jaeger
• If the tracingConfigRef flag is not specified, it defaults to a default tracing configuration specific to the set tracingLirary. This default tracing configuration is provided in the APIcast image itself

The configuration is mounted into the APIcast pod by looking at a config key in the provided secret name and mounted in /opt/app-root/src/tracing-configs/tracing-config-<tracing_library_name>-<secret_name>, for example in opt/app-root/src/tracing-configs/tracing-config-jaeger-mysecretname

Pending:

• Verification

[miguelsorianod]

With the current implementation the OpenTracing configuration is being provided with a Secret but in the official APIcast product documentation I see a ConfigMap is used. Maybe in this case a Secret is not needed and we should use a ConfigMap instead?

[miguelsorianod]

Ready for a first review @eguzki before I proceed to do some verifications

[eguzki]

looks good

[miguelsorianod]

@eguzki I think this should be ready

[eguzki]

LGTM

minor comments dropped