New TrafficLog design (new name: MeshLogging)

[lahabana]

Description

Rebuild traffic log to have it work with the new selectors.

Open questions:

• should the backends be inlined in the policy? This would make it easier to have per zone backends.
• We should support inbound and outbound logs.
• MeshAccessLog for grpc #3324
• logging config uses defaultBackend in mesh config when we use enabledBackend in other policies #3242

[slonka]

@lahabana - could you explain how inlining would make it easier to have per zone backends?

should the backends be inlined in the policy? This would make it easier to have per zone backends.

FYI @lobkovilya

[lahabana]

Because you define a policy:

name: log-zone-a
spec:
   targetRef:
      type: proxySubset
      tags:
        kuma.io/zone: foo
    to:
       - targetRef:
            type: mesh
          default:
             backend: my-zone-specific-backend 

[slonka]

I'm still not sure. It's this:

apiVersion: kuma.io/v1alpha1
kind: Mesh
metadata:
  name: default
spec:
  logging:
    backends:
      - name: logstash-zone-a
        type: tcp
        conf:
          address: 127.0.0.1:5000
      - name: logstash-zone-b
        type: tcp
        conf:
          address: 127.0.0.2:5000
---
type: MeshLogging
mesh: default
name: log-zone-a
spec:
  targetRef:
    kind: MeshSubset
    tags:
      kuma.io/zone: zone-a
  from:
    - targetRef:
        kind: Mesh
        name: default
      default:
        backends:
          - logstash-zone-a
---
type: MeshLogging
mesh: default
name: log-zone-b
spec:
  targetRef:
    kind: MeshSubset
    tags:
      kuma.io/zone: zone-b
  from:
    - targetRef:
        kind: Mesh
        name: default
      default:
        backends:
          - logstash-zone-b

vs this:

type: MeshLogging
mesh: default
name: log-zone-a
spec:
  targetRef:
    kind: MeshSubset
    tags:
      kuma.io/zone: zone-a
  from:
    - targetRef:
        kind: Mesh
        name: default
      default:
        backends:
          - name: logstash-zone-a
            type: tcp
            conf:
              address: 127.0.0.1:5000
---
type: MeshLogging
mesh: default
name: log-zone-b
spec:
  targetRef:
    kind: MeshSubset
    tags:
      kuma.io/zone: zone-b
  from:
    - targetRef:
        kind: Mesh
        name: default
      default:
        backends:
          - name: logstash-zone-b
            type: tcp
            conf:
              address: 127.0.0.2:5000

how is one easier than the other? or, is my example wrong?