CA

The CA issuer represents a Certificate Authority whereby its certificate and private key are stored inside the cluster as a Kubernetes Secret, and will be used to sign incoming certificate requests. This internal CA certificate can then be used to trust resulting signed certificates.

This issuer type is typically used in a Public Key Infrastructure (PKI) setup to secure your infrastructure components to establish mTLS or otherwise provide a means to issue certificates where you also own the private key. Signed certificates will not be trusted by clients, such a web browser, by default.

Deployment

In order to create your CA issuer, you must first submit your CA certificate and signing private key to the Kubernetes API server so that cert-manager is able to retrieve them and sign certificates. This secret should reside in the same namespace as the Issuer, or otherwise in the Cluster Resource Namespace in the case of a ClusterIssuer. The Cluster Resource Namespace is defaulted as being the cert-manager namespace, however can be configured using the --cluster-resource-namespace flag on the cert-manager controller component.

Below is an example of a secret resource that will be used for signing. Take note of the index keys used for each field as these are required in order for cert-manager to find the certificate and key. Also note that, like all secrets, data must be base64 encoded. The command $ cat crt.pem | base64 -w0 should help you on GNU-based systems (Debian, Ubuntu, etc.) and $ cat crt.pem | base64 -b0 on BSD-based systems (most notably macOS).

apiVersion: v1
kind: Secret
metadata:
  name: ca-key-pair
  namespace: sandbox
data:
  tls.crt: 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
  tls.key: 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

Note: If your issuer represents an intermediate, ensure that tls.crt contains the issuer's full chain in the correct order: issuer -> intermediate(s) -> root. The root (self-signed) CA certificate is optional, but adding it will ensure that the correct CA certificate is stored in the secrets for issued Certificates under the ca.crt key. If you fail to provide a complete chain, it might not be possible for consumers of issued Certificates to verify whether they're trusted.

Next is to deploy the CA issuer which references this Secret. This is done by referencing the secret name under the ca stanza in the Issuer spec.

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: ca-issuer
  namespace: sandbox
spec:
  ca:
    secretName: ca-key-pair

Optionally, you can specify CRL Distribution Points. An array of strings each of which identifies the location of the CRL from which the revocation of this certificate can be checked:

...
spec:
  ca:
    secretName: ca-key-pair
    crlDistributionPoints:
    - "http://example.com"

Once deployed, you can then check that the issuer has been successfully configured by checking the ready status of the certificate. Replace issuers here with clusterissuers if that is what has been deployed.

configured for the CLI.

$ kubectl get issuers ca-issuer -n sandbox -o wide
NAME          READY   STATUS                AGE
ca-issuer     True    Signing CA verified   2m

Certificates are now ready to be requested by using the CA Issuer named ca-issuer within the sandbox namespace.