Admission controllers

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This is the current list of admission controllers used by Docker:

Default

Custom

  • UCPAuthorization This custom admission controller does several things:
    • Annotates Docker Compose-on-Kubernetes Stack resources with the identity of the user performing the request so that the Docker Compose-on-Kubernetes resource controller can manage Stacks with correct user authorization.
    • Detects when ServiceAccount resources are deleted so that they can be correctly removed from UCP’s Node scheduling authorization backend.
    • Simplifies creation of RoleBindings and ClusterRoleBindings resources by automatically converting user, organization, and team Subject names into their corresponding unique identifiers.
    • Prevents users from deleting the built-in cluster-admin ClusterRole or ClusterRoleBinding resources.
    • Prevents under-privileged users from creating or updating PersistintVolume resources with host paths.
    • Works in conjunction with the built-in PodSecurityPolicies admission controller to prevent under-privileged users from creating Pods with privileged options.
  • CheckImageSigning Enforces UCP’s Docker Content Trust policy which, if enabled, requires that all pods use container images which have been digitally signed by trusted and authorized users which are members of one or more teams in UCP.
  • UCPNodeSelector Adds a com.docker.ucp.orchestrator.kubernetes:* toleration to pods in the kube-system namespace and removes com.docker.ucp.orchestrator.kubernetes tolerations from pods in other namespaces. This ensures that user workloads do not run on swarm-only nodes, which UCP taints with com.docker.ucp.orchestrator.kubernetes:NoExecute. It also adds a node affinity to prevent pods from running on manager nodes depending on UCP’s settings.

Note: you cannot enable or disable your own admission controllers. For more information, see Supportability of custom kubernetes flags in universal control plane

For more information about pod security policies in Docker, see Pod security policies.

cluster, psp, security