Kubeblocks Engine Clickhouse

ClickHouse Engine Entry

Use this as the primary create-time entry for ClickHouse. Tier-1 ClickHouse never falls back to kubeblocks-engine-generic.

Cold-Start Contract

• Run kubeblocks-preflight whenever the environment is not already profiled.
• Treat engine-create-matrix as the create-time truth for topology, version strategy, sizing, validation, next hops, and forbidden routes.
• Use observability-capability-matrix before promising scrape readiness.
• Use addon examples as evidence, not as a reason to invent a different create path.

Topology Selection

• Default topology: cluster
• standalone: use for local analytics evaluation or one-node testing only.
• cluster: default production path; this includes ClickHouse server shards plus ClickHouse Keeper coordination.
• If the user needs distributed analytics or failover, stay on cluster.

ServiceVersion / Version Strategy

• Strategy: use the stable addon default from current examples unless the user explicitly pins a serviceVersion
• Current addon evidence surfaces ClickHouse 22, 24, and 25, with example-driven defaults anchored on shipped addon lines.
• If the user asks for "latest", stay on an addon-backed supported line instead of a raw upstream tag.

Preflight Interpretation

• storage_class: required before apply because server and keeper data persist to PVCs.
• volume_binding_mode: confirm storage placement before distributed rollout.
• addon_readiness: ClickHouse addon must be installed first.
• observability_mode: ClickHouse has scrape examples; choose existing-stack vs bootstrap before rollout.

Sizing Profiles

• demo: standalone or a very small cluster for query validation.
• production: cluster with keeper, shard sizing, and storage sized for analytical retention and merge pressure.
• Treat shard count and replica count as data-distribution decisions, not just replica cosmetics.

Minimal Create Path

apiVersion: apps.kubeblocks.io/v1
kind: Cluster
metadata:
  name: <cluster>
  namespace: <ns>
spec:
  terminationPolicy: Delete

• Do not leave this skill to read raw addon examples before drafting the manifest.
• Set clusterDef: clickhouse for every ClickHouse create path in this wave.
• standalone: set topology: standalone and keep the data plane as a single ClickHouse service path without shardings:.
• cluster: set topology: cluster, keep name: ch-keeper under componentSpecs, and put the actual ClickHouse data plane under shardings: with template name: clickhouse.
• Validate with kubectl apply --dry-run=server -f <clickhouse-cluster.yaml>.
• Apply with kubectl apply -f <clickhouse-cluster.yaml>.
• Watch kubectl get cluster <name> -n <ns> -w until the phase is Running.

Connection and Validation

• Supported connection methods: in-cluster service, port-forward, nodeport-or-loadbalancer
• First validation step: kubectl get cluster <name> -n <ns> and wait for Running.
• Default validation: connect with clickhouse-client --host <endpoint> --port 9000 --user admin --password.
• If TLS is enabled, validate the secure client path before handing the endpoint to users.

Next Hops

• Day-2 operations currently route to kubeblocks-op-lifecycle, kubeblocks-op-horizontal-scale, kubeblocks-op-backup, and kubeblocks-observability-router.
• Password and Secret handling can route to kubeblocks-manage-accounts when the create path used system accounts.
• Treat kubeblocks-configure-tls as engine-specific validation work, not a universal default.
• Do not send this path to kubeblocks-rebuild-replica; ClickHouse recovery should stay on backup, restore, or troubleshoot paths.
• Route keeper, shard, or exposure failures to kubeblocks-troubleshoot.

Forbidden Routes

• Never route ClickHouse create through kubeblocks-engine-generic or kubeblocks-family-ts-analytics.
• If the request is really GreptimeDB or another analytics engine, switch engines before apply.

Evidence Anchors

• Use the evidence anchors below only as optional secondary evidence and parity checks after the manifest is already drafted here. A cold-start runtime should not need these files, but a stronger agent may inspect them when available.
• Current addon evidence: examples/clickhouse/cluster-standalone.yaml, examples/clickhouse/cluster.yaml, examples/clickhouse/cluster-with-nodeport.yaml.