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Kubernetes Sidecar Client

This guide shows you how to access a Ziti service from a pre-existing (or third party) application that's running in a Kubernetes Pod. To provide access to the service, we will deploy the ziti-tunnel client in a sidecar container.

Overview

The Ziti Network Quickstart walked you through standing up a Ziti instance and accessing a Ziti service from your workstation with ziti-tunnel. In this guide we'll deploy the same ziti-tunnel client, but instead of running it from the command line we will deploy it in a sidecar container in a Kubernetes Pod.

This guide also demonstrates ziti-tunnel's internal DNS server, which allows us to access Ziti services by hostname instead of IP address.

Here's some detail on how the various intercept modes work on Linux

Solution Overview

Diagram of solution

Prerequisites

  • Complete the Ziti Network Quickstart. This guide uses the Ziti Controller and Ziti Edge Router that are created in the Ziti Quickstart.
  • Admin-level access to a Kubernetes cluster via kubectl.

Create an Identity and AppWAN

This guide will re-use the "eth0.ziti.cli" service that was created in the Ziti Network Quickstart.

We will create a new identity for our client, with a new AppWAN that uses the eth0.ziti.cli service.

Create the Identity:

ziti edge controller create identity device tunnel-sidecar -o tunnel-sidecar.jwt

Create the AppWAN and reference the service created in the Ziti Network Quickstart. We'll be using eth0.ziti.cli here but if you created eth0.ziti.ui in the quickstart - use that instead. Also note that in the tunnel-sidecar-demo.yaml:

ziti edge controller create app-wan ziti-tunnel-appwan -i tunnel-sidecar -s eth0.ziti.cli

Create a Kubernetes Secret

The ziti-tunnel sidecar will access its identity by mounting a Kubernetes secret in the container. We can mount the JWT as a secret like this:

$ kubectl create secret generic tunnel-sidecar.jwt --from-file=tunnel-sidecar.jwt
secret/tunnel-sidecar.jwt created

Deploy the Pod

Deploy a Pod that runs a client application and ziti-tunnel as a sidecar container. For this demonstration, the client application is curl. Our Pod runs curl in a loop so we can see content from our Ziti service in the Pod's logs.

Save the following yaml to a file named tunnel-sidecar-demo.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: tunnel-sidecar-pv-claim
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 100Mi
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: ziti-tunnel-sidecar-demo
spec:
replicas: 1
selector:
matchLabels:
app: ziti-tunnel-sidecar-demo
strategy:
type: Recreate
template:
metadata:
labels:
app: ziti-tunnel-sidecar-demo
spec:
containers:
- image: centos
name: testclient
command: ["sh","-c","while true; set -x; do curl -sSLf eth0.ziti.cli 2>&1; set +x; sleep 5; done"]
- image: netfoundry/ziti-tunnel:latest
name: ziti-tunnel
env:
- name: NF_REG_NAME
value: tunnel-sidecar
volumeMounts:
- name: tunnel-sidecar-jwt
mountPath: "/var/run/secrets/kubernetes.io/enrollment-token"
readOnly: true
- name: ziti-tunnel-persistent-storage
mountPath: /netfoundry
securityContext:
capabilities:
add:
- NET_ADMIN
dnsPolicy: "None"
dnsConfig:
nameservers:
- 127.0.0.1
- 8.8.8.8
restartPolicy: Always
volumes:
- name: ziti-tunnel-persistent-storage
persistentVolumeClaim:
claimName: tunnel-sidecar-pv-claim
- name: tunnel-sidecar-jwt
secret:
secretName: tunnel-sidecar.jwt

You'll notice that the ziti-tunnel sidecar container has a few requirements:

  1. The name of the identity that is assumed by ziti-tunnel must be passed into the container with the NF_REG_NAME environment variable.
  2. The secret that we created above for the enrollment token must be mounted into the container at "/var/run/secrets/netfoundry.io/enrollment-token".
  3. A persistent volume must be mounted at "/netfoundry". This volume is used to save the json file that is created when the one-time enrollment token is used. If this volume is not persistent, you will need to provide a new enrollment token each time the Pod is restarted!

Once the yaml is saved, we can deploy the Pod with kubectl

$ kubectl apply -f ./tunnel-sidecar-demo.yaml
persistentvolumeclaim/tunnel-sidecar-pv-claim created
deployment.apps/ziti-tunnel-sidecar-demo created

Test the Service

First we need to get the name of the Pod that Kubernetes deployed for us:

$ kubectl get pods
ziti-tunnel-sidecar-demo-749c476989-6wpfn 1/1 Running 0 42s

Then we can tail the logs for the "testclient" container:

$ kubectl logs -f ziti-tunnel-sidecar-demo-749c476989-6wpfn --container testclient
54.67.121.213
54.67.121.213
54.67.121.213

Notice that the curl client is using the DNS name that we provided in the Ziti service definition to make the request.