add status information to reflect the number of AZs a cluster is spread across

[k15r]

Description

Add a status field in the NATS-CR to reflect the current number of AZs used by the NATS cluster

Acceptance

• watch the Pods created for the NATS cluster
• sum up the number of different AZs used by the K8S-Nodes the NATS Pods are scheduled on
• for clusters with 3 or more Nodes set a condition reflecting if the cluster is HACapable (3 AZs (or more for bigger cluster sizes) are currently used)
• export the number of AZs used by NATS Pods as a metric
  • either create a query for the monitoring system
  • or create a configuration to reflect the newly introduced status field using kubestate-metrics

[mfaizanse]

Status

Different zones

status:
  availabilityZonesUsed: 3
  conditions:
  - lastTransitionTime: "2024-04-23T12:12:55Z"
    message: StatefulSet is ready
    reason: Available
    status: "True"
    type: StatefulSet
  - lastTransitionTime: "2024-04-23T12:12:55Z"
    message: NATS is deployed
    reason: Deployed
    status: "True"
    type: Available
  - lastTransitionTime: "2024-04-23T12:12:55Z"
    message: NATS is deployed in different availability zones.
    reason: Deployed
    status: "True"
    type: AvailabilityZones
  state: Ready
  url: nats://eventing-nats.kyma-system.svc.cluster.local:4222

Same zones

status:
  availabilityZonesUsed: 1
  conditions:
  - lastTransitionTime: "2024-04-23T13:00:30Z"
    message: StatefulSet is ready
    reason: Available
    status: "True"
    type: StatefulSet
  - lastTransitionTime: "2024-04-23T13:00:30Z"
    message: NATS is deployed
    reason: Deployed
    status: "True"
    type: Available
  - lastTransitionTime: "2024-04-23T12:15:52Z"
    message: 'NATS is not currently using enough availability zones (Recommended:
      3, current: 1).'
    reason: Unknown
    status: "False"
    type: AvailabilityZones
  state: Warning
  url: nats://eventing-nats.kyma-system.svc.cluster.local:4222

Metrics

# HELP nats_manager_availability_zones_used_count The number of availability zones used by NATS Pods.
# TYPE nats_manager_availability_zones_used_count gauge
nats_manager_availability_zones_used_count 3

# HELP nats_manager_cr_nats_nodes_count The cluster size configured in the NATS CR.
# TYPE nats_manager_cr_nats_nodes_count gauge
nats_manager_cr_nats_nodes_count 3

[mfaizanse]