Demo Telepresence Intercept

In this lesson, you’ll learn how to use Telepresence to intercept traffic from a Kubernetes service and run the workload locally for fast, iterative debugging.

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Prerequisites

A Kubernetes cluster and kubectl configured to the correct context
Telepresence CLI installed (brew install telepresence or see the official docs)
Node.js (v14+) and npm

Make sure your Kubernetes context is set to the target namespace, and you have permissions to create interceptions.

1. List Your Deployments

Identify the deployment you want to intercept:

kubectl get deployment
# Example output:
# NAME             READY   UP-TO-DATE   AVAILABLE   AGE
# auth-depl        1/1     1            1           4h55m
# inventory-depl   1/1     1            1           5h32m
# products-depl    1/1     1            1           4h47m

2. Create an Intercept

First, connect Telepresence to your cluster if you haven’t already:

telepresence connect

Then run:

telepresence intercept auth-depl -p 8000:3000

Local Port	Container Port	Description
8000	3000	Auth service HTTP traffic

Here’s the relevant snippet from the Kubernetes manifest:

# Deployment spec excerpt
spec:
  template:
    spec:
      containers:
      - name: auth
        image: sanjeevkt720/telepresence-auth
        ports:
        - containerPort: 3000
          name: web
---
apiVersion: v1
kind: Service
metadata:
  name: auth-service
spec:
  selector:
    app: auth
  ports:
    - port: 3000
      targetPort: 3000

You should see output similar to:

Using Deployment auth-depl
  Intercept name          : auth-depl
  State                   : ACTIVE
  Workload kind           : Deployment
  Destination             : 127.0.0.1:8000
  Service Port Identifier : 3000/TCP
  Volume Mount Point      : /tmp/telfs-1680244885
  Intercepting            : all TCP connections

3. Run the Service Locally

Switch to your local service directory and start the server on port 8000:

cd ~/telepresence/auth
npm install
npm run dev

Ensure your Express app listens on port 8000:

// index.js
const express = require("express");
const app = express();
const port = 8000;

app.get("/", (req, res) => {
  res.json({ message: "auth service running locally via Telepresence" });
});

app.listen(port, () => {
  console.log(`Auth service listening on port ${port}`);
});

4. Verify the Intercept

Use curl to hit the Kubernetes service name. Telepresence will route this to your local process:

curl http://auth-service:3000

Expected response:

{"message":"auth service running locally via Telepresence"}

5. Inspect the Pod

Observe both the original container and Telepresence’s traffic agent:

POD_NAME=$(kubectl get pod -l app=auth -o jsonpath='{.items[0].metadata.name}')
kubectl describe pod $POD_NAME

Look for two containers:

auth (port 3000/TCP)
traffic-agent (port 9900/TCP)

6. Remove the Intercept

When you’re done debugging, clear the intercept:

telepresence leave auth-depl
telepresence list
# Should report: No active intercepts

7. Switch to the Products Service

Stop your local auth service (Ctrl+C)
List deployments again:
kubectl get deployment

Intercept the products deployment:

telepresence intercept products-depl -p 8000:3000

Run the products service locally:

cd ~/telepresence/products
npm install
npm run dev

Verify with:

curl "http://products-service:3000/?product_ids=1,2,3"

8. Debugging an Error

If your request hangs and you see:

TypeError: Failed to parse URL from undefined?product_ids=1,2,3

Inspect your route handler:

app.get("/", async (req, res) => {
  try {
    const productIds = req.query.product_ids;
    const idsArray = productIds.split(",").map(id => parseInt(id, 10));
    const response = await fetch(`${apiURL}?product_ids=${idsArray.join(",")}`);
    // ...
  } catch (error) {
    console.error(error);
  }
});

apiURL is undefined locally because the environment variable from the Pod isn’t set in your shell.

9. Import Environment Variables

To mirror the Pod’s settings, pull the env vars into your local shell:

# Fetch one of the app pods
POD_NAME=$(kubectl get pod -l app=products -o jsonpath='{.items[0].metadata.name}')
# Export all environment variables from the container to your local session
kubectl exec $POD_NAME -- printenv | grep API_URL | sed 's/^/export /' > pod-env.sh
source pod-env.sh

Now restart your local service so it picks up API_URL and any other Pod-specific variables.

Course Introduction

Telepresence For Kubernetes

Demo Telepresence Intercept

Prerequisites

1. List Your Deployments

2. Create an Intercept

3. Run the Service Locally

4. Verify the Intercept

5. Inspect the Pod

6. Remove the Intercept

7. Switch to the Products Service

8. Debugging an Error

9. Import Environment Variables

Links and References

Watch Video

​Prerequisites

​1. List Your Deployments

​2. Create an Intercept

​3. Run the Service Locally

​4. Verify the Intercept

​5. Inspect the Pod

​6. Remove the Intercept

​7. Switch to the Products Service

​8. Debugging an Error

​9. Import Environment Variables

​Links and References

Watch Video

Prerequisites

1. List Your Deployments

2. Create an Intercept

3. Run the Service Locally

4. Verify the Intercept

5. Inspect the Pod

6. Remove the Intercept

7. Switch to the Products Service

8. Debugging an Error

9. Import Environment Variables

Links and References