Using Existing Operators

Where Operators Come From

OperatorHub.io catalogs OLM-packaged operators; ArtifactHub aggregates those alongside Helm charts, OPA policies, and more. Each entry shows supported distributions, channels (stable, fast, edge), and maturity — the Operator Maturity model grades capabilities from install/upgrade through failover and auto-tuning.

OLM (Operator Lifecycle Manager), standard on OpenShift and installable elsewhere, manages the lifecycle: it installs ClusterServiceVersion (CSV) objects describing the operator's permissions, deploy modes (AllNamespaces vs OwnNamespace), webhooks, and upgrade rules. Operators not distributed through OLM are usually plain Helm charts — check ArtifactHub for both.

Installing and Managing

With OLM, subscribe to a package:

apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata: { name: etcd-operator, namespace: operators }
spec:
  name: etcd-operator
  source: community-operators
  channel: stable
  installPlanApproval: Automatic

Then inspect: kubectl get csv -n operators, kubectl get subscriptions -n operators, kubectl get installplan -n operators. With Manual approval, upgrades create an InstallPlan you must approve explicitly — a deliberate production gate. Without OLM, install via Helm (helm install postgresql bitnami/postgresql); for air-gapped fleets, build an index with opm and serve a local catalog source.

Pitfalls and Interview Angles

Maturity mismatch. An operator graded only at "install" will not upgrade your data safely — for stateful workloads demand upgrade/failover levels or be prepared to run the upgrade yourself.

Cluster-wide RBAC. Many operators request AllNamespaces and ClusterRoles spanning many groups. Read the CSV/Role before install; OwnNamespace or SingleNamespace modes exist for a reason.

Conflicting owners. Two operators managing the same CRD or webhook fight over finalizers and conversions — check which CSV owns each CRD.

Channel blindness. installPlanApproval: Automatic on stable can apply an upgrade the moment it appears; pin versions or switch to Manual for critical operators.

Interview angle: explain the OLM object chain (Subscription → InstallPlan → CSV → deployment) and how you evaluate an operator before it touches production.