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Configure a Kubernetes build farm to use self-signed certificates

CI build infrastructure pods can interact with servers using self-signed certificates. This option is useful for organizations that prefer to use internal certificates instead of certificates generated by a public Certificate Authority (CA).

Important notes​

  • This topic assumes that you are familiar with how to implement SSL in Kubernetes. General information about implementing SSL is outside the scope of this topic.
  • With a Kubernetes cluster build infrastructure, all Build and Push steps use kaniko. Kaniko uses the path /kaniko/ssl/certs/additional-ca-cert-bundle.crt to read certificates.
  • Harness uses a UBI image for the Git Clone step. UBI reads certificates from /etc/ssl/certs/ca-bundle.crt.
  • Different base images use different paths as their default certificate location. For example, Alpine images use this path to recognize certificates: /etc/ssl/certs/ca-certificates.crt For any other image, make sure you verify the default certificate path.

STO pipelines​

If you have STO scan steps in your pipeline, you can set up your certificates using the workflow described below. However, there are some additional steps and requirements. For more information, go to Adding Custom Artifacts to STO Pipelines.

Enable self-signed certificates​

  1. Create a Kubernetes secret or config map with the required certificates in the same namespace used by the Harness Delegate.

    Here's a YAML example:

    apiVersion: v1  
    kind: Secret  
    metadata:  
      name: addcerts  
      namespace: harness-delegate-ng  
    type: Opaque  
    stringData:                             
      ca.bundle: |  
        -----BEGIN CERTIFICATE-----  
        XXXXXXXXXXXXXXXXXXXXXXXXXXX  
        -----END CERTIFICATE-------  
        -----BEGIN CERTIFICATE-----  
        XXXXXXXXXXXXXXXXXXXXXXXXXXX  
        -----END CERTIFICATE-------

  2. Mount the secret as a volume on the Delegate pod.

    For details, go to Configure a Pod to Use a Volume for Storage in the Kubernetes documentation.

    You need to specify the following environment variables in the Delegate pod:

    • ADDITIONAL_CERTS_PATH: The path to the certificates in the Delegate, for example: /tmp/ca.bundle.
    • CI_MOUNT_VOLUMES: A comma-separated list of source:destination mappings. The source is the certificate path on the delegate, and the destination is the path where you want to expose the certificates on the build containers, for example: /tmp/ca.bundle:/etc/ssl/certs/ca-bundle.crt,/tmp/ca.bundle:/kaniko/ssl/certs/additional-ca-cert-bundle.crt.

    This list must include all certificates that your build containers need to interact with external services.

    Here's a YAML example:

    apiVersion: apps/v1  
    kind: StatefulSet  
    spec:  
      template:  
        spec:  
            env:  
            - name: ADDITIONAL_CERTS_PATH  
              value: /tmp/ca.bundle  
            - name: CI_MOUNT_VOLUMES  
              value: /tmp/ca.bundle:/etc/ssl/certs/ca-bundle.crt,/tmp/ca.bundle:/kaniko/ssl/certs/additional-ca-cert-bundle.crt  
            volumeMounts:  
            - name: certvol  
              mountPath: /tmp/ca.bundle  
              subPath:  ca.bundle 
           volumes:  
            - name: certvol  
              secret:  
                secretName: addcerts  
                items:  
                - key: ca.bundle  
                  path: ca.bundle
    caution

    Make sure that the destination path is not same as the default CA certificate path of the corresponding container image.

    If you want to override the default certificate file, make sure the Kubernetes secret or config map (from step one) includes all certificates required by the pipelines that will use this build infrastructure.

  3. Restart the Delegate. Once it is up and running, exec into the container and ensure that the volume exists at the mounted path and contains your certificates.

Troubleshooting​

If your builds fail due to a problem connecting to the scm service, add SCM_SKIP_SSL=true to the environment section of the delegate YAML. For more information about this issue, go to Troubleshoot CI.

If the volumes are not getting mounted to the build containers, or you continue to see certificate errors in your pipeline, try the following:

  1. Add a Run step that prints the contents of the destination path. For example, you can include a command such as:

    cat /kaniko/ssl/certs/additional-ca-cert-bundle.crt

  2. Double-check that the base image used in the step reads certificates from the same path given in the destination path on the Delegate.