In cert-manager, the
represents a human readable definition of a certificate request that is to be
honored by an issuer which is to be kept up-to-date. This is the usual way that
you will interact with cert-manager to request signed certificates.
In order to issue any certificates, you’ll need to configure an
Issuer resource first.
Creating Certificate Resources
Certificate resource specifies fields that are used to generated certificate
signing requests which are then fulfilled by the issuer type you have
Certificates specify which issuer they want to obtain the
certificate from by specifying the
Certificate resource, for the
www.example.com DNS names,
spiffe://cluster.local/ns/sandbox/sa/example URI Subject Alternative Name,
that is valid for 90 days and renews 15 days before expiry is below. It contains
an exhaustive list of all options a
Certificate resource may have however only
a subset of fields are required as labelled.
apiVersion: cert-manager.io/v1 kind: Certificate metadata: name: example-com namespace: sandbox spec: # Secret names are always required. secretName: example-com-tls duration: 2160h # 90d renewBefore: 360h # 15d subject: organizations: - jetstack # The use of the common name field has been deprecated since 2000 and is # discouraged from being used. commonName: example.com isCA: false privateKey: algorithm: RSA encoding: PKCS1 size: 2048 usages: - server auth - client auth # At least one of a DNS Name, URI, or IP address is required. dnsNames: - example.com - www.example.com uris: - spiffe://cluster.local/ns/sandbox/sa/example ipAddresses: - 192.168.0.5 # Issuer references are always required. issuerRef: name: ca-issuer # We can reference ClusterIssuers by changing the kind here. # The default value is Issuer (i.e. a locally namespaced Issuer) kind: Issuer # This is optional since cert-manager will default to this value however # if you are using an external issuer, change this to that issuer group. group: cert-manager.io
The signed certificate will be stored in a
Secret resource named
example-com-tls in the same namespace as the
Certificate once the issuer has
successfully issued the requested certificate.
Certificate will be issued using the issuer named
ca-issuer in the
sandbox namespace (the same namespace as the
Note: If you want to create an
Issuerthat can be referenced by
Certificateresources in all namespaces, you should create a
ClusterIssuerresource and set the
durationfields must be specified using a Go
time.Durationstring format, which does not allow the
d(days) suffix. You must specify these values using
hsuffixes instead. Failing to do so without installing the
webhook componentcan prevent cert-manager from functioning correctly
Note: Take care when setting the
renewBeforefield to be very close to the
durationas this can lead to a renewal loop, where the
Certificateis always in the renewal period. Some
notBeforefield on their issued x509 certificates before the issue time to fix clock-skew issues, leading to the working duration of a certificate to be less than the full duration of the certificate. For example, Let’s Encrypt sets it to be one hour before issue time, so the actual working duration of the certificate is 89 days, 23 hours (the full duration remains 90 days).
A full list of the fields supported on the Certificate resource can be found in the API reference documentation
cert-manager supports requesting certificates that have a number of custom key
usages and extended key usages. Although cert-manager will attempt to honor this
request, some issuers will remove, add defaults, or otherwise completely ignore
the request and is determined on an issuer by issuer basis. The
Issuer will always return certificates matching the usages you have
Unless any number of usages has been set, cert-manager will set the default requested usages of “digital signature”, “key encipherment”, and “server auth”. cert-manager will not attempt to request a new certificate if the current certificate does not match the current key usages set.
An exhaustive list of supported key usages can be found in the API reference documentation.
Temporary Certificates whilst Issuing
When requesting certificates using ingress-shim, the component
ingress-gce, if used, requires that a temporary certificate is present while
waiting for issuance of a signed certificate when serving. To facilitate this,
if the annotation
"cert-manager.io/issue-temporary-certificate": "true" is
present on the certificate, a self signed temporary certificate will be present
Secret until it is overwritten once the signed certificate has been
Configuring private key rotation
WARNING: This feature requires enabling the
ExperimentalCertificateControllersfeature gate by passing the
--feature-gates=ExperimentalCertificateControllers=trueflag to the controller component, or adding
--set featureGates=ExperimentalCertificateControllers=truewhen deploying using the Helm chart.
When a certificate is re-issued for any reason, including because it is nearing expiry, when a change to the spec is made or a re-issuance is manually triggered, cert-manager supports configuring the ‘private key rotation policy’ to either always re-use the existing private key (the default behavior) or to regenerate a new private key on each issuance (the recommended behavior).
This is configured using the
spec.privateKey.rotationPolicy like so:
apiVersion: cert-manager.io/v1 kind: Certificate metadata: name: my-cert ... spec: secretName: my-cert-tls dnsNames: - example.com privateKey: rotationPolicy: Always
There are two supported rotation policies:
- Never (default): a private key is only generated if one does not already exist in
the target Secret resource (using the
tls.keykey). All further issuance’s will re-use this private key. This is the default in order to maintain compatibility with previous releases.
- Always: a new private key will be generated each time a new certificate is issued.
It is recommended you configure this
rotationPolicyon your Certificate resources as it is good practice to rotate private keys when a certificate is renewed.
Some Issuer types may disallow re-using private keys. If this is the case, you must explicitly
rotationPolicy for each of your Certificates accordingly.
Cleaning up Secrets when Certificates are deleted
By default, cert-manager does not delete the
Secret resource containing the signed certificate when the corresponding
Certificate resource is deleted.
This means that deleting a
Certificate won’t take down any services that are currently relying on that certificate, but the certificate will no longer be renewed.
Secret needs to be manually deleted if it is no longer needed.
If you would prefer the
Secret to be deleted automatically when the
Certificate is deleted, you need to configure your installation to pass the
--enable-certificate-owner-ref flag to the controller.