certdeploy

A small utility intended to assist with pushing TLS certificates (most notably wildcard certificates produced by Let's Encrypt) to multiple Kubernetes clusters. It was built with the intention of having one place where certificates are managed and renewed separate from the clusters.

Usage

Deploy certificates to multiple Kubernetes clusters

Usage:
  certdeploy [flags]

Flags:
  -c, --config string       path to config file
  -h, --help                help for certdeploy
  -k, --kubeconfig string   path to kubeconfig file (default "$HOME/.kube/config")

Configuration

A simple example of a configuration file containing one cluster might look something like this:

secrets:
  # Key to reference the secret by
  tls-dev:
    # The name of the secret to create
    name: tls-dev
    # Key value pairs representing the data the secret will be created with
    files:
      tls.crt: /etc/letsencrypt/live/myawesomedevdomain.com/fullchain.pem
      tls.key: /etc/letsencrypt/live/myawesomedevdomain.com/privkey.pem
    # A list of namespaces where this secret will be created
    namespaces:
      - kube-system
      - my-ns

clusters:
    # A label to use for the cluster in output
  - name: dev
    # The context to use from the kubeconfig file
    context: dev-cluster
    # A list of secrets (defined above) to create in this cluster
    secrets:
      - tls-dev

Kubernetes Integration

It is highly recommended you use a Kubernetes service account when connecting to the clusters. There are some scripts included to assist with this in the scripts directory. These scripts may not be suitable for all use cases, so please modify them as necessary for your particular situation.

The service-account.yml file is an example of such a service account. It creates a cluster-wide role that allows the service account to get secrets by name, create secrets, and update secrets. This is the basic functionality that certdeploy uses. You can secure this even further if you already know what the names of your secrets will be:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: certdeploy
rules:
  - apiGroups: [""]
    resources: ["secrets"]
    resourceNames: ["my-tls-secret"]
    verbs: ["get", "create", "update"]

This will limit the service account to only being able to get, create, or update a secret with the name my-tls-secret.

To use this service account when connecting to clusters, you will need a kubeconfig file with the necessary credentials. The script create-kubeconfig.sh can assist with this once the service account has been created in your cluster(s). This script assumes that the machine you're running it from already has one or more Kubernetes contexts available to connect to clusters via tools like kubectl. Using that, it can then retrieve the service account's credentials and generate a new kubeconfig based on that information. It can also be run multiple times against the same kubeconfig file to generate multiple contexts, which is useful when using certdeploy for multiple clusters.

The following command will create a kubeconfig file in the current directory, where certdeploy is the name of the service account:

scripts/create-kubeconfig.sh certdeploy

Optionally, you can also control where the output will be placed:

scripts/create-kubeconfig.sh -o ./cfg/kubeconfig certdeploy

More information is available by running scripts/create-kubeconfig.sh --help.