tailscale/docs/k8s

Overview

There are quite a few ways of running Tailscale inside a Kubernetes Cluster. This doc covers creating and managing your own Tailscale node deployments in cluster. If you want a higher level of automation, easier configuration, automated cleanup of stopped Tailscale devices, or a mechanism for exposing the Kubernetes API server to the tailnet, take a look at Tailscale Kubernetes operator.

⚠️ Note that the manifests generated by the following commands are not intended for production use, and you will need to tweak them based on your environment and use case. For example, the commands to generate a standalone proxy manifest, will create a standalone Pod- this will not persist across cluster upgrades etc. ⚠️

Instructions

Setup

1. (Optional) Create the following secret which will automate login.
   You will need to get an auth key from Tailscale Admin Console.
   If you don't provide the key, you can still authenticate using the url in the logs.

   apiVersion: v1
   kind: Secret
   metadata:
     name: tailscale-auth
   stringData:
     TS_AUTHKEY: tskey-...
   

2. Tailscale (v1.16+) supports storing state inside a Kubernetes Secret.

   Configure RBAC to allow the Tailscale pod to read/write the tailscale secret.

   export SA_NAME=tailscale
   export TS_KUBE_SECRET=tailscale-auth
   make rbac | kubectl apply -f-
   

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 | kubectl apply -f-
   # If not using an auth key, authenticate by grabbing the Login URL here:
   kubectl logs nginx ts-sidecar
   

2. Check if you can to 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 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 SOCKS proxy or HTTP proxy.

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

   make userspace-sidecar | kubectl apply -f-
   # If not using an auth key, authenticate by grabbing the Login URL here:
   kubectl logs nginx ts-sidecar
   

2. Check if you can to 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 | kubectl apply -f-
   # If not using an auth key, authenticate by grabbing the Login URL here:
   kubectl logs proxy
   

3. Check if you can to 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 | kubectl apply -f-
   # If not using an auth key, authenticate by grabbing the Login URL here:
   kubectl logs subnet-router
   

3. In the Tailscale 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
   

Multiple replicas

Note that if you want to use the Pod manifests generated by the commands above in a multi-replica setup (i.e a multi-replica StatefulSet) you will need to change the mechanism for storing tailscale state to ensure that multiple replicas are not attemting to use a single Kubernetes Secret to store their individual states.

To avoid proxy state clashes you could either store the state in memory or an emptyDir volume, or you could change the provided state Secret name to ensure that a unique name gets generated for each replica.

Option 1: storing in an emptyDir

You can mount an emptyDir volume and configure the mount as the tailscale state store via TS_STATE_DIR env var. You must also set TS_KUBE_SECRET to an empty string.

An example:

kind: StatefulSet
metadata:
  name: subnetrouter
spec:
  replicas: 2
  ...
  template:
    ...
    spec:
      ...
      volumes:
      - name: tsstate
        emptyDir: {}
      containers:
      - name: tailscale
        env:
        - name: TS_STATE_DIR
          value: /tsstate
        - name: TS_KUBE_SECRET
          value: ""
        volumeMounts:
        - name: tsstate
          mountPath: /tsstate

The downside of this approach is that the state will be lost when a Pod is deleted. In practice this means that when you, for example, upgrade proxy versions you will get a new set of Tailscale devices with different hostnames.

Option 2: dynamically generating unique Secret names

If you run the proxy as a StatefulSet, the Pods get stable identifiers. You can use that to pass an individual, static state Secret name to each proxy:

kind: StatefulSet
metadata:
  name: subnetrouter
spec:
  replicas: 2
  ...
  template:
    ...
    spec:
      ...
       containers:
      - name: tailscale
        env:
        - name: TS_KUBE_SECRET
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.name

In this case, each replica will store its state in a Secret named the same as the Pod and as Pod names for a StatefulSet do not change if Pods get recreated, proxy state will persist across cluster and proxy version updates etc.