Configure Cert Manager for ClickHouse Certificates

Generate TLS certificates for ClickHouse Server and Keeper using Cert Manager.

For the concepts behind this guide — what each certificate is for, how verification modes work, and how rotation behaves — see PKI and mTLS in ClickHouse Private.

Prerequisites

Cert Manager installed in the cluster
Cluster name chosen (this guide uses default-xx-01 as an example)

Steps

1. Create a Certificate Issuer

Create a self-signed Issuer to act as the certificate authority:

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: selfsigned-issuer
  namespace: ns-default-xx-01
spec:
  selfSigned: {}

Note: The Issuer is namespace-scoped and must be in the same namespace as the Certificate resources that reference it. A self-signed issuer is suitable for testing. For production, review the list of issuer options.

2. Create Certificate Resources

Create a Certificate resource for ClickHouse Server:

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: clickhouse-server-tls
  namespace: ns-default-xx-01
spec:
  secretName: default-xx-01-server-cert-secret
  dnsNames:
    - "*.c-default-xx-01-server-headless.ns-default-xx-01.svc.cluster.local"
  issuerRef:
    name: selfsigned-issuer
    kind: Issuer

This creates a Kubernetes secret named default-xx-01-server-cert-secret containing keys ca.crt, tls.crt, and tls.key. Repeat with the appropriate dnsNames and secretName for Keeper if needed.

3. Configure Helm Values to Use Cert-Manager Secret Keys

By default, the onprem-clickhouse-cluster Helm chart expects secret keys named ca.crt, server.crt, and server.key. Cert Manager produces ca.crt, tls.crt, and tls.key. Override the key names in your Helm values:

server:
  openSSL:
    enabled: true
    secret:
      caKey: ca.crt
      certKey: tls.crt
      keyKey: tls.key

The certificates are mounted at /etc/clickhouse-server/certs/ for Server and /etc/clickhouse-keeper/certs/ for Keeper. The Helm chart generates the correct OpenSSL configuration automatically.

Notes on ca.crt Availability

The ca.crt key is only added to the secret if it is available from the issuer. For example, ACME issuers do not include ca.crt. In that case, add the public root CA to the ca.crt key manually, or use trust-manager to generate a CA bundle and target the correct secret.

ClickHouse Cloud

Bring Your Own Cloud

ClickHouse Private

Configure Cert Manager for ClickHouse Certificates

Prerequisites

Steps

1. Create a Certificate Issuer

2. Create Certificate Resources

3. Configure Helm Values to Use Cert-Manager Secret Keys

Notes on ca.crt Availability

​Prerequisites

​Steps

​1. Create a Certificate Issuer

​2. Create Certificate Resources

​3. Configure Helm Values to Use Cert-Manager Secret Keys

​Notes on ca.crt Availability

Prerequisites

Steps

1. Create a Certificate Issuer

2. Create Certificate Resources

3. Configure Helm Values to Use Cert-Manager Secret Keys

Notes on ca.crt Availability