KKP uses cert-manager for managing all TLS certificates used for KKP itself, as well as Dex and the Identity-Aware Proxies (IAP). The default configuration sets up Certificate Issuers for Let’s Encrypt, but other issuers can be configured as well. This section describes the various options for using a custom CA: using cert-manager or managing certificates manually outside of the cluster.
cert-manager offers a CA Issuer that can automatically create and sign certificates inside the cluster. This requires that the CA itself is stored inside the cluster as a Kubernetes Secret, so care must be taken to prevent unauthorized access (e.g. by setting up proper RBAC rules).
If having the CA certificate and key inside the cluster is not a problem, this approach is recommended, as it introduces the least friction and can be achieved rather easily.
cert-manager Helm chart that is part of KKP does not support creating non-ACME
ClusterIssuers (i.e ClusterIssuers that do not use Let’s Encrypt). New issuers must therefore be
created manually. Please follow the description in
the cert-manager documentation.
Once the new ClusterIssuer has been created, KKP and the IAP need to be adjusted to use the new issuer.
For KKP, update the
KubermaticConfiguration and configure
spec: ingress: certificateIssuer: name: my-own-ca-issuer
Re-apply the changed configuration and the KKP Operator will reconcile the Certificate resource, after which cert-manager will provision a new certificate Secret.
Similarly, update your Helm
values.yaml that is used for the Dex/IAP deployment and configure
the new issuer:
dex: certIssuer: name: my-own-ca-issuer iap: certIssuer: name: my-own-ca-issuer
iap Helm chart to perform the changes and update the Certificate resources.
If issuing certificates inside the cluster is not possible, static certificates can also be provided. The cluster admin is responsible for renewing and updating them as needed. Going forward, it is assumed that proper certificates have already been created and now need to be configured inside the cluster.
The KKP Operator manages a single Ingress for the KKP API/dashboard. This by default includes setting up the required annotations and spec settings for usage with cert-manager. However, if the cert-manager integration is disabled, the cluster admin is free to manage these settings themselves.
To disable the cert-manager integration, set the
spec.ingress.certificateIssuer.name to an empty string
spec: ingress: certificateIssuer: name: ""
It is now possible to set
spec.tls on the
kubermatic Ingress to a custom certificate:
spec: tls: - secretName: my-custom-kubermatic-cert hosts: - kubermatic.example.com
Refer to the Kubernetes documentation for details on the format for certificate Secrets.
The same technique used for KKP is applicable to Dex as well: Set the name of the cert issuer to an empty
string to be able to configure your own certificates. Update the Helm
values.yaml used to deploy the
chart like so:
dex: certIssuer: name: ""
Re-deploy the chart and the Certificate resource will not be created anymore. You have to manually create
dex-tls Secret in Dex’s namespace. This Secret follows the
same format as the one for KKP’s API.
The configuration is identical to Dex: Disable the cert issuer’s name and then manually create the TLS certificates.
iap: certIssuer: name: ""
For each configured Deployment (
iap.deployments) a matching Secret needs to be created. For a Deployment
grafana, the Secret needs to be called
Both the KKP API and the OAuth-Proxy from the IAP need to validate the OAuth tokens (generated by Dex, by default). If the the token issuer uses a custom CA, this CA needs to be configured for KKP and all IAPs.
In both cases, the full certificate chain (including intermediates) needs to be configured.
The token issuer (not to be confused with a cert-manager certificate issuer) is configured in the
KubermaticConfiguration and by default requires a valid certificate. The required adjustments for this
are the same for custom internal or external CA’s.
spec: auth: caBundle: "" tokenIssuer: https://example.com/dex # this should never be enabled in production environments skipTokenIssuerTLSVerify: false
If the certificate used for Dex is not issued by a CA that is trusted by default (e.g. Let’s Encrypt),
the issuing CA’s certificate chain needs to be configured in
spec.auth.caBundle. This field is a
multiline string that should contain the PEM-encoded certificate(s), like so:
spec: auth: caBundle: | -----BEGIN CERTIFICATE----- <certificate 1 here> -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- <certificate 2 here> -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- <certificate 3 here> -----END CERTIFICATE-----
Do note that if the OIDC Endpoint Feature is enabled in KKP, this CA bundle is also configured for the Kubernetes apiserver, so that it can also validate the tokens issued by Dex.
The certificate chain can be put into a Kubernetes Secret and then be referred to from the
Create a Secret inside the IAP’s namespace (
iap by default) and then update your
values.yaml like so:
iap: customProviderCA: secretName: my-ca-secret secretKey: ca.crt
iap Helm chart to apply the changes.
Generally the KKP stack is built to use dedicated certificates for each Ingress / application, but it’s possible to instead configure a single (usually wildcard) certificate in nginx that will be used as the default certificate for all domains.
As with all other custom certificates, create a new Secret with the certificate and private key in it,
and then adjust your Helm
values.yaml to configure nginx like so:
nginx: extraArgs: # The value of this flag is in the form "namespace/name". - '--default-ssl-certificate=mynamespace/mysecret'
nginx-ingress-controller Helm chart to enable the changes.