MinIO Kubernetes Operator

Kubernetes Version

MinIO supports maintained Kubernetes APIs for deploying the Operator.

Kubernetes infrastructure running end-of-life API versions may exhibit unexpected or undesired behavior if used for deploying the Operator.

Kustomize and kubectl

Kustomize is a YAML-based templating tool that allows you to define Kubernetes resources in a declarative and repeatable fashion. Kustomize is included with the kubectl command line tool.

This procedure assumes that your local host machine has both the matching version of kubectl for your Kubernetes cluster and the necessary access to that cluster to create new resources.

The default MinIO Operator Kustomize template provides a starting point for customizing configurations for your local environment. You can modify the default Kustomization file or apply your own patches to customize the Operator deployment for your Kubernetes cluster.

Kubernetes TLS Certificate API

The MinIO Operator manages TLS Certificate Signing Requests (CSR) using the Kubernetes certificates.k8s.io TLS certificate management API to create signed TLS certificates in the following circumstances:

• When autoCert is enabled.

• For the MinIO Console when the MINIO_CONSOLE_TLS_ENABLE environment variable is set to on.

• For STS service when OPERATOR_STS_ENABLED environment variable is set to on.

• For retrieving the health of the cluster.

The MinIO Operator reads certificates inside the operator-ca-tls secret and syncs this secret within the tenant namespace to trust private certificate authorities, such as when using cert-manager.

For any of these circumstances, the MinIO Operator requires that the Kubernetes kube-controller-manager configuration include the following configuration settings:

• --cluster-signing-key-file - Specify the PEM-encoded RSA or ECDSA private key used to sign cluster-scoped certificates.

• --cluster-signing-cert-file - Specify the PEM-encoded x.509 Certificate Authority certificate used to issue cluster-scoped certificates.

The Kubernetes TLS API uses the CA signature algorithm for generating new TLS certificate. MinIO recommends ECDSA (e.g. NIST P-256 curve) or EdDSA (e.g. Curve25519) TLS private keys/certificates due to their lower computation requirements compared to RSA. See Supported TLS Cipher Suites for a complete list of supported TLS Cipher Suites.

If the Kubernetes cluster is not configured to respond to a generated CSR, the Operator cannot complete initialization. Some Kubernetes providers do not specify these configuration values by default.

To check whether the kube-controller-manager specifies the cluster signing key and certificate files, use the following command:

kubectl get pod kube-controller-manager-$CLUSTERNAME-control-plane \
  -n kube-system -o yaml

• Replace $CLUSTERNAME with the name of the Kubernetes cluster.

Confirm that the output contains the highlighted lines. The output of the example command above may differ from the output in your terminal:

 spec:
 containers:
 - command:
     - kube-controller-manager
     - --allocate-node-cidrs=true
     - --authentication-kubeconfig=/etc/kubernetes/controller-manager.conf
     - --authorization-kubeconfig=/etc/kubernetes/controller-manager.conf
     - --bind-address=127.0.0.1
     - --client-ca-file=/etc/kubernetes/pki/ca.crt
     - --cluster-cidr=10.244.0.0/16
     - --cluster-name=my-cluster-name
     - --cluster-signing-cert-file=/etc/kubernetes/pki/ca.crt
     - --cluster-signing-key-file=/etc/kubernetes/pki/ca.key
 ...