Concepts

Generally, a ctrlmesh-proxy container will be injected into each operator Pod that has configured in ShardingConfigs. This proxy container will intercept and handle the connection by between API/Oth Server and controllers/webhooks in the Pod.

ApiServer proxy method:

• iptables nat:
• fake kubeconfig:

The ctrlmesh-manager dispatches rules to the proxies, so that they can route requests according to the rules.

A core CRD of ControllerMesh is ShardingConfig. It contains all rules for user's controller:

apiVersion: ctrlmesh.kusionstack.io/v1alpha1
kind: ShardingConfig
metadata:
  name: sharding-demo
  namespace: operator-demo
spec:
  controller:
    leaderElectionName: operator-leader
  webhook:
    certDir: /tmp/webhook-certs
    port: 9443
  limits:
  - relateResources:
    - apiGroups:
      - '*'
      resources:
      - pods
      - services
    selector:
      matchExpressions:
      - key: ctrlmesh.kusionstack.io/namespace
        operator: In
        values:
        - ns-a
        - ns-b
      matchLabels:
        app: foo
  selector:
    matchExpressions:
    - key: statefulset.kubernetes.io/pod-name
      operator: In
      values:
      - operator-demo-0

• selector: for all pods under a shard. It can be a subset of pods under a StatefulSet.
• controller: configuration for controller, including leader election name
• webhook: configuration for webhook, including certDir and port of this webhook
• limits: shard isolation is achieved through a set of ObjectSelector.

When manager is first launched, shard labels will be added to all configured resources.

• ctrlmesh.kusionstack.io/sharding-hash: the hash value calculated based on the namespace ranges from 0 to 31.
• ctrlmesh.kusionstack.io/namespace: the namespace referring to this resource.
• ctrlmesh.kusionstack.io/control: under ctrlmesh-manager control.

In this repo, we only support ObjectSelector type of flow control, which means the ctrlmesh-proxy will proxy http/s requests to the ApiServer, and inject a LabelSelector into the request param for the requested resource type.

Router: