Lab 2: Volume Mounting¶

What will we learn?¶

• How Telepresence mirrors a pod’s filesystem to your local machine
• Mounting ConfigMaps and Secrets locally during an intercept
• Using the TELEPRESENCE_ROOT environment variable
• Developing locally with real cluster configuration

Introduction¶

• When you intercept a service with --mount, Telepresence mirrors the pod’s entire filesystem to a local directory
• This includes ConfigMaps, Secrets, Service Account tokens, and any other mounted volumes
• Your local application can read the same config files the pod would see in the cluster

graph TB
    subgraph cluster["Kubernetes Cluster"]
        CM["ConfigMap<br/>backend-config"] --> POD["backend pod<br/>/etc/config/"]
        SA["ServiceAccount<br/>Token"] --> POD
    end
    subgraph local["Local Machine"]
        POD -.->|"telepresence --mount"| MOUNT["/tmp/tel-mount/etc/config/<br/>/tmp/tel-mount/var/run/secrets/"]
    end

    style CM fill:#8b5cf6,color:#fff
    style SA fill:#6366f1,color:#fff
    style MOUNT fill:#10b981,color:#fff

Prerequisites¶

• cluster-east running with apps deployed
• Lab 1 completed (familiar with intercept workflow)

Step 01 - Examine the ConfigMap¶

kubectl config use-context kind-cluster-east

# View the ConfigMap that the backend pod uses
kubectl get configmap backend-config -n telepresence-lab -o yaml

Step 02 - Connect and Intercept with Mount¶

telepresence connect

# Create intercept with explicit mount path
telepresence intercept backend \
  --port 5000 \
  --namespace telepresence-lab \
  --mount /tmp/tel-mount

Step 03 - Explore the Mounted Volumes¶

# List the mount root
ls -la /tmp/tel-mount/

# Find all mounted files
find /tmp/tel-mount -type f 2>/dev/null | head -20

# Read the ConfigMap files
cat /tmp/tel-mount/etc/config/app.conf
cat /tmp/tel-mount/etc/config/features.json

environment=development
log_level=debug
database_host=datastore.telepresence-lab.svc.cluster.local
cache_ttl=300

Step 04 - Use Cluster Config in Local Development¶

Create a local backend that reads the cluster’s actual configuration:

# local_backend_with_config.py
from http.server import HTTPServer, BaseHTTPRequestHandler
import json, os

# Telepresence sets this env var to the mount root
MOUNT_ROOT = os.environ.get('TELEPRESENCE_ROOT', '/tmp/tel-mount')

# Read the cluster's ConfigMap - same files the pod would see
with open(f'{MOUNT_ROOT}/etc/config/app.conf') as f:
    config_text = f.read()

with open(f'{MOUNT_ROOT}/etc/config/features.json') as f:
    features = json.load(f)

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header('Content-Type', 'application/json')
        self.end_headers()
        response = {
            "source": "LOCAL with cluster config",
            "config": config_text.strip(),
            "features": features,
        }
        self.wfile.write(json.dumps(response, indent=2).encode())

print(f"Running with cluster config from {MOUNT_ROOT}")
HTTPServer(('0.0.0.0', 5000), Handler).serve_forever()

python3 local_backend_with_config.py

Step 05 - Verify¶

curl http://backend.telepresence-lab.svc.cluster.local:5000/

The response should include the cluster’s ConfigMap values, served from your local machine.

Step 06 - Cleanup¶

telepresence leave backend-telepresence-lab
telepresence quit

Key Environment Variables¶

Validation Checklist¶