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In this guide, we’ll walk through intercepting the products deployment with Telepresence, exporting its Kubernetes environment variables into a .env file, and running the service locally so it can call the inventory service exactly as it does inside the cluster.

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1. Reproducing the Error

First, start an intercept on the products deployment: 
telepresence intercept products-depl -p 8000
When you request multiple products, you’ll see this in your local logs: 
TypeError: Failed to parse URL from undefined?product_ids=1,2,3
    at new URL (node:internal/url:816:29)
    at new Request (node:internal/deps/undici:9474:25)
    at fetch (node:internal/deps/undici:10203:26)
  code: 'ERR_INVALID_URL',
  input: 'undefined?product_ids=1,2,3'
}
This error shows that API_URL is undefined in your local environment.

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2. Application Code (index.js)

The service reads API_URL from the environment and queries the inventory service: 
const express = require("express");
const fetch = require("node-fetch");
const app = express();
const port = 8000;

const apiURL = process.env.API_URL; // undefined when running without .env
console.log("API_URL:", apiURL);

const products = [
  { id: 1, name: "iphone 14", price: 900, category: "electronics", onSale: false },
  { id: 2, name: "Samsung 40in TV", price: 500, category: "electronics", onSale: true },
  { id: 3, name: "Apple MacbookPro", price: 2500, category: "electronics", onSale: false }
];

app.get("/", async (req, res) => {
  try {
    const productIds = req.query.product_ids;
    const idsArray = productIds.split(",").map(id => parseInt(id.trim(), 10));
    const filtered = products.filter(p => idsArray.includes(p.id));

    const response = await fetch(`${apiURL}?product_ids=${idsArray.join(",")}`);
    if (!response.ok) throw new Error(`HTTP error! Status: ${response.status}`);

    const data = await response.json();
    res.json({ data });
  } catch (error) {
    console.error(error);
    res.status(500).send("Internal Server Error");
  }
});

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

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3. Kubernetes Deployment Spec

Normally, the Pod spec injects API_URL: 
spec:
  template:
    spec:
      containers:
        - name: products
          ports:
            - containerPort: 8000
              name: web
          env:
            - name: API_URL
              value: "http://inventory-service:3000/"
---
apiVersion: v1
kind: Service
metadata:
  name: products-service
spec:
  type: LoadBalancer
Since Telepresence runs the container locally, those Pod environment variables won’t be available by default.

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4. Pulling Environment Variables with Telepresence

  1. Stop and remove the current intercept 
    telepresence list
telepresence leave products-depl
  2. Restart with .env dump and mount 
    telepresence intercept products-depl \
  -p 8000 \
  --env-file my-envs.env \
  --mount=true
    This generates my-envs.env: 
    API_URL=http://inventory-service:3000/
AUTH_SERVICE_PORT=tcp://10.100.10.52:3000
INVENTORY_SERVICE_PORT_3000_TCP_ADDR=10.100.246.69
KUBERNETES_PORT_443_TCP_ADDR=10.100.1.1
...
The --mount=true flag ensures your local process can read my-envs.env as if it were on your filesystem.

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5. Loading the .env File in Node.js

Install and configure dotenv: 
npm install dotenv
At the top of index.js, override existing env vars: 
require("dotenv").config({ override: true });
const express = require("express");
const fetch = require("node-fetch");
// ... rest of the code ...
Now when you run the intercept, process.env.API_URL matches the cluster’s value.

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6. Testing the Setup

With the intercept active, send a request through your cluster’s LoadBalancer: 
curl http://a45190821a848c3d9760c9e3b9-515600148.us-east-1.elb.amazonaws.com:3000/?product_ids=1,2,3
You should receive: 
{
  "data": [
    {
      "id": 1,
      "name": "iphone 14",
      "price": 900,
      "category": "electronics",
      "onSale": false,
      "inventoryCount": 158
    },
    {
      "id": 2,
      "name": "Samsung 40in TV",
      "price": 500,
      "category": "electronics",
      "onSale": true,
      "inventoryCount": 54
    },
    {
      "id": 3,
      "name": "Apple MacbookPro",
      "price": 2500,
      "category": "electronics",
      "onSale": false,
      "inventoryCount": 607
    }
  ]
}
This confirms that your local service reads the same environment variables as in Kubernetes and correctly calls the inventory service.

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