Issuer

Issuers, and ClusterIssuers, are Kubernetes resources that represent certificate authorities (CAs) that are able to generate signed certificates by honoring certificate signing requests. All cert-manager certificates require a referenced issuer that is in a ready condition to attempt to honor the request.

An example of an Issuer type is CA. A simple CA Issuer is as follows:

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

This is a simple Issuer that will sign certificates based on a private key. The certificate stored in the secret ca-key-pair can then be used to trust newly signed certificates by this Issuer in a Public Key Infrastructure (PKI) system.

Namespaces

An Issuer is a namespaced resource, and it is not possible to issue certificates from an Issuer in a different namespace. This means you will need to create an Issuer in each namespace you wish to obtain Certificates in.

If you want to create a single Issuer that can be consumed in multiple namespaces, you should consider creating a ClusterIssuer resource. This is almost identical to the Issuer resource, however is non-namespaced so it can be used to issue Certificates across all namespaces.

Supported Issuers

cert-manager supports a number of ‘in-tree’, as well as ‘out-of-tree’ Issuer types. An exhaustive list of these Issuer types can be found in the cert-manager configuration documentation.