in_kubernetes_events: allow listening to a single namespace.

[pwhelan]

Summary

Add the kube_namespace parameter to specify a single namespace to listen to events for. This is crucial when listening to events with a service account that does not have cluster-wide permissions for events.

To create a token

kubectl create serviceaccount $SVC_ACCOUNT_NAME
kubectl create role $ROLE_EVENTS --verb=get,list --resource=events
kubectl create rolebinding $ROLE_EVENTS_BINDING \
    --serviceaccount=system:serviceaccount:$NAMESPACE:$SVC_ACCOUNT_NAME \
    --role=$ROLE_EVENTS
kubectl create token $SVC_ACCOUNT_NAME > token.txt

---

Enter [N/A] in the box, if an item is not applicable to your change.

Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature

Backporting

• Backport to latest stable release.

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.