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Using TLS Certificates

Replicated KOTS provides default self-signed certificates that renew automatically. For embedded clusters created with Replicated kURL, the self-signed certificate renews 30 days before expiration when you enable the kURL EKCO add-on version 0.7.0 and later.

Custom TLS options are supported:

  • Existing clusters: The expectation is for the end customer to bring their own Ingress Controller such as Contour or Istio and upload their own kubernetes.io/tls secret. For an example, see Ingress with TLS in the Kubernetes documentation.

  • Embedded kURL clusters: End customers can upload a custom TLS certificate. Replicated kURL creates a TLS secret that can reused by other Kubernetes resources, such as Deployment or Ingress, which can be easier than providing and maintaining multiple certificates. As a vendor, you can enable the use of custom TLS certificates with these additional resources.

For example, if your application does TLS termination, your deployment would need the TLS secret. Or if the application is connecting to another deployment that is also secured using the same SSL certificate (which may not be a trusted certificate), the custom TLS certificate can be used to do validation without relying on the trust chain.

Get the TLS Secret​

kURL sets up a Kubernetes secret called kotsadm-tls. The secret stores the TLS certificate, key, and hostname. Initially, the secret has an annotation set called acceptAnonymousUploads. This indicates that a new TLS certificate can be uploaded by the end customer during the deployment process. For more information about deployment, see About Installing an Application in the Enterprise User documentation.

Before you can reference the TLS certificate in other resources, you must get the kotsadm-tls secret output.

To get the kots-adm-tls secret, run:

kubectl get secret kotsadm-tls -o yaml

In the output, the tls.crt and tls.key hold the certificate and key that can be referenced in other Kubernetes resources.

Example Output:

apiVersion: v1
kind: Secret
type: kubernetes.io/tls
metadata:
  name: kotsadm-tls
data:
  tls.crt: <base64_encoded>
  tls.key: <base64_encoded>

Use TLS in a Deployment Resource​

This procedure shows how to reference the kotsadm-tls secret using an example nginx Deployment resource (kind: Deployment).

To use the kotsadm-tls secret in a Deployment resource:

  1. In the Deployment YAML file, configure SSL for volumeMounts and volumes, and add the kotsadm-tls secret to volumes:

    Example:

    apiVersion:  apps/v1
    kind: Deployment
    metadata:
      name: nginx
    spec:
      template:
        spec:
          containers:
            volumeMounts:
              - mountPath: "/etc/nginx/ssl"
                name: nginx-ssl
                readOnly: true
          volumes:
            - name: nginx-ssl
              secret:
                secretName: kotsadm-tls

  2. Deploy the release, and then verify the pod deployment using the kubectl exec command:

    Example:

    export POD_NAME=nginx-<hash>
    kubectl exec -it ${POD_NAME} bash

  3. Run the ls and cat commands to verify that the certificate and key were deployed to the specified volumeMount:

    Example:

    $ ls /etc/nginx/ssl
    tls.crt tls.key

    $ cat /etc/nginx/ssl/tls.crt
    -----BEGIN CERTIFICATE-----
    MIID8zCCAtugAwIBAgIUZF+NWHnpJCt2R1rDUhYjwgVv72UwDQYJKoZIhvcNAQEL

    $ cat /etc/nginx/ssl/tls.key
    -----BEGIN PRIVATE KEY-----
    MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQCyiGNuHw2LY3Rv

Use TLS in an Ingress Resource​

You can add the kotsadm-tls secret to the Ingress resource to terminate TLS at the contour layer. The following example shows how to configure secretName: kotsadm-tls under the TLS hosts field in an Ingress resource (kind: Ingress):

Example:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: nginx
spec:
  rules:
  tls:
    - hosts:
      - 'tls.foo.com'
        secretName: kotsadm-tls
  - host: tls.foo.com
    http:
      paths:
        - path: /
          backend:
            serviceName: nginx
            servicePort: 80
note

tls.foo.com must resolve to a valid IP, and also must match the Common Name (CN) or Subjective Alternative Name (SAN) of the TLS certificate.