Demo Volumes

In this lesson we’ll learn how to access Kubernetes volumes attached to a pod when intercepting that service with Telepresence for Kubernetes. By mounting pod volumes on your local machine you can let a local process read the same ConfigMaps or files the in-cluster pod uses — enabling a dev workflow where your local service behaves like the cluster service. Key pieces:

A local Node.js application that simulates the service.
A Deployment that mounts a ConfigMap as a volume.
The ConfigMap with the data keys.
Telepresence intercept steps that mount the pod volume locally.

Local Node.js example (local service)

This Node.js example reads configuration from the environment (process.env) but, when using Telepresence mounts, you can also read values from files placed by a ConfigMap mount.

require('dotenv').config({ override: true });
const express = require('express');
const app = express();
const port = 8000;

const apiURL = process.env.API_URL;
console.log('API_URL:', apiURL);

const products = [
  {
    id: 1,
    name: "iphone 14",
    price: 900,
    category: "electronics",
    onSale: false,
  }
];

app.get('/products', (req, res) => {
  res.json(products);
});

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

Deployment volume configuration (mounting a ConfigMap)

This snippet shows the Deployment mounting a ConfigMap named db-info as a volume called db-config into the pod at /tmp.

spec:
  selector:
    matchLabels:
      app: products
  template:
    metadata:
      labels:
        app: products
    spec:
      volumes:
      - name: db-config
        configMap:
          name: db-info
      containers:
      - name: products
        image: sanjeevkt720/telepresence-products
        imagePullPolicy: Always
        volumeMounts:
        - name: db-config
          mountPath: /tmp
        ports:
        - containerPort: 3000
          name: web
        env:
          # environment entries (if any)

ConfigMap (db-info)

The ConfigMap contains DB connection values that will appear as files when mounted as a volume.

apiVersion: v1
kind: ConfigMap
metadata:
  name: db-info
data:
  DB_HOST: "prod.db"
  DB_PASSWORD: "mypassword123"
  DB_USERNAME: "myusername123"

How it works — explanation

The Deployment mounts the db-info ConfigMap into the pod at /tmp using a volume named db-config.
When the ConfigMap is mounted as a volume, Kubernetes creates files in the container filesystem — one file per key (DB_HOST, DB_PASSWORD, DB_USERNAME) with the corresponding content.
When you run a Telepresence intercept that mounts pod volumes, Telepresence mirrors that volume onto your local filesystem so your local process can access the same files.
Telepresence either creates a random mount path by default or you can request a specific mount path.

Mounting a ConfigMap as files does not populate process environment variables (e.g., process.env). If your application expects env vars, either: (a) use envFrom or explicit env entries in the Deployment for in-cluster pods, (b) read the files from the Telepresence mount in your local app, or (c) generate a local .env or export variables before running your local process.

Quick reference table

Resource	Purpose	Example / Notes
Node.js app	Local service for development	Reads `process.env` or files from Telepresence mount
Deployment volume	Mounts ConfigMap into pod filesystem	volume `db-config` -> mountPath `/tmp`
ConfigMap `db-info`	Stores DB keys as plain data	Keys become files: `DB_HOST`, `DB_PASSWORD`, `DB_USERNAME`
Telepresence intercept	Mounts pod volumes to local filesystem	`telepresence intercept products-depl -p 8000 --env-file .env --mount=true`

Telepresence commands and examples

Check current intercepts:

telepresence list
# Example output:
# auth-depl       : ready to intercept (traffic-agent already installed)
# inventory-depl  : ready to intercept (traffic-agent not yet installed)
# products-depl   : ready to intercept (traffic-agent already installed)

Create an intercept and mount volumes (automatic/random mount location):

telepresence intercept products-depl -p 8000 --env-file .env --mount=true

When you run that command, Telepresence prints details similar to:

Workload kind              : Deployment
Destination                : 127.0.0.1:8000
Service Port Identifier   : 3000/TCP
Volume Mount Point        : /tmp/telfs-2189772442
Intercepting              : all TCP connections

Open a new shell and inspect the automatic mount point (use the mount path shown in your Telepresence output):

# change into the Telepresence mount folder shown in output
cd /tmp/telfs-2189772442/tmp

ls
cat DB_HOST
cat DB_PASSWORD
# mypassword123

Note: Telepresence exposes the ConfigMap keys as files in the mount directory. Your local application must either read those files (or use symlinks) or you must set environment variables locally so the app can access config via process.env.

If you prefer a consistent local path instead of a random Telepresence mount path, you can specify a fixed mount path with the --mount= option. Ensure the target directory is writable by Telepresence.

Specify a custom mount path

Leave the current intercept:

telepresence leave products-depl

Re-intercept and provide a mount path (example /tmp/example123):

telepresence intercept products-depl -p 8000 --env-file .env --mount=/tmp/example123

Inspect the chosen path:

cd /tmp/example123/tmp

ls
cat DB_HOST
# prod.db

Summary

Telepresence for Kubernetes can mount Kubernetes volumes (including ConfigMaps mounted as volumes) into a local directory when you intercept a service.
By default Telepresence creates a mount at a random path; use --mount=/path to choose a fixed path.
Mounting a ConfigMap exposes its keys as files — it does not automatically create environment variables in your local process. Adjust your local application to read the Telepresence mount, create symlinks, or export variables before running.

Links and references

Telepresence course: Telepresence for Kubernetes
Project docs: Telepresence documentation
Kubernetes docs: ConfigMap and Volumes

Course Introduction

Telepresence For Kubernetes

Local Node.js example (local service)

Deployment volume configuration (mounting a ConfigMap)

ConfigMap (db-info)

How it works — explanation

Quick reference table

Telepresence commands and examples

Specify a custom mount path

Summary

Links and references

Watch Video

​Local Node.js example (local service)

​Deployment volume configuration (mounting a ConfigMap)

​ConfigMap (db-info)

​How it works — explanation

​Quick reference table

​Telepresence commands and examples

​Specify a custom mount path

​Summary

​Links and references

Watch Video

Local Node.js example (local service)

Deployment volume configuration (mounting a ConfigMap)

ConfigMap (db-info)

How it works — explanation

Quick reference table

Telepresence commands and examples

Specify a custom mount path

Summary

Links and references