Tailscale on Kubernetes

Kubernetes is a popular method for deploying, scaling, and managing containerized applications. There are many ways you can run Tailscale in inside a Kubernetes Cluster, e.g., as a sidecar, as a proxy, or as a subnet router. This doc shows several common ways.

Tailscale’s managed Docker image

Tailscale has a published Docker image that Tailscale manages and builds from source. It’s available in Docker Hub and GitHub Packages, just run:

docker pull tailscale/tailscale:latest

or

docker pull ghcr.io/tailscale/tailscale:latest

The current version of the Makefile required for the examples in this doc is in the tailscale repo.

Prerequisites

You can follow the examples in this doc by cloning from GitHub. For example:

gh repo clone tailscale/tailscale
cd tailscale/docs/k8s

Setup

  1. (Optional) You can choose to use an auth key to automate your container logging in to your tailnet. Navigate to the auth keys page of the admin console. We recommend using an ephemeral key for this purpose, since it will automatically clean up devices after they shut down.

    Tailscale's auth key generation page

    If you don’t provide the key, you can still authenticate by logging in at the URL provided in logs when using the container image below.

    apiVersion: v1
    kind: Secret
    metadata:
      name: tailscale-auth
    stringData:
      TS_AUTH_KEY: tskey-0123456789abcdef
    
  2. Build and push the container

    export IMAGE_TAG=tailscale-k8s:latest
    make push
    
  3. Tailscale (v1.16 or later) supports storing state inside a Kubernetes Secret.

    Configure role-based access control (RBAC) to allow the Tailscale pod to read/write the tailscale secret.

    export SA_NAME=tailscale
    export TS_KUBE_SECRET=tailscale-auth
    make rbac
    

Sample Sidecar

Running as a sidecar allows you to directly expose a Kubernetes pod over Tailscale. This is particularly useful if you do not wish to expose a service on the public internet. This method allows bi-directional connectivity between the pod and other devices on the tailnet. You can use ACLs to control traffic flow.

  1. Create and login to the sample nginx pod with a Tailscale sidecar:

    make sidecar
    # If not using an auth key, authenticate by grabbing the Login URL here:
    kubectl logs nginx ts-sidecar
    
  2. Check if you can connect to nginx over Tailscale:

    curl http://nginx
    

    Or, if you have MagicDNS disabled:

    curl "http://$(tailscale ip -4 nginx)"
    

Userspace Sidecar

You can also run the sidecar in userspace networking mode. The obvious benefit is reducing the amount of permissions Tailscale needs to run. The downside is that for outbound connectivity from the pod to the tailnet you would need to use either the SOCKS5 proxy or HTTP proxy.

  1. Create and login to the sample nginx pod with a Tailscale sidecar:

    make userspace-sidecar
    # If not using an auth key, authenticate by grabbing the Login URL here:
    kubectl logs nginx ts-sidecar
    
  2. Check if you can connect to nginx over Tailscale:

    curl http://nginx
    

    Or, if you have MagicDNS disabled:

    curl "http://$(tailscale ip -4 nginx)"
    

Sample Proxy

Running a Tailscale proxy allows you to provide inbound connectivity to a Kubernetes Service.

  1. Provide the ClusterIP of the service you want to reach by either:

    Creating a new deployment

    kubectl create deployment nginx --image nginx
    kubectl expose deployment nginx --port 80
    export TS_DEST_IP="$(kubectl get svc nginx -o=jsonpath='{.spec.clusterIP}')"
    

    Using an existing service

    export TS_DEST_IP="$(kubectl get svc <SVC_NAME> -o=jsonpath='{.spec.clusterIP}')"
    
  2. Deploy the proxy pod:

    make proxy
    # If not using an auth key, authenticate by grabbing the Login URL here:
    kubectl logs proxy
    
  3. Check if you can connect to nginx over Tailscale:

    curl http://proxy
    

    Or, if you have MagicDNS disabled:

    curl "http://$(tailscale ip -4 proxy)"
    

Subnet Router

Running a Tailscale subnet router allows you to access the entire Kubernetes cluster network (assuming NetworkPolicies allow) over Tailscale.

  1. Identify the Pod/Service CIDRs that cover your Kubernetes cluster. These will vary depending on which CNI you are using and on the Cloud Provider you are using. Add these to the TS_ROUTES variable as comma-separated values.

    SERVICE_CIDR=10.20.0.0/16
    POD_CIDR=10.42.0.0/15
    export TS_ROUTES=$SERVICE_CIDR,$POD_CIDR
    
  2. Deploy the subnet-router pod.

    make subnet-router
    # If not using an auth key, authenticate by grabbing the Login URL here:
    kubectl logs subnet-router
    
  3. In the machines page of the admin console, ensure that the routes for the subnet-router are enabled.

  4. Make sure that any client you want to connect from has --accept-routes enabled.

  5. Check if you can connect to a ClusterIP or a PodIP over Tailscale:

    # Get the Service IP
    INTERNAL_IP="$(kubectl get svc <SVC_NAME> -o=jsonpath='{.spec.clusterIP}')"
    # or, the Pod IP
    # INTERNAL_IP="$(kubectl get po <POD_NAME> -o=jsonpath='{.status.podIP}')"
    INTERNAL_PORT=8080
    curl http://$INTERNAL_IP:$INTERNAL_PORT
    

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