monaco/new-backend/TUNNEL-CONNECTION-FIX.md

Tunnel Connection Options - Troubleshooting Guide

The Problem

When the tunnel runs in Docker and tries to reach your backend on the host, there are different ways to address the host machine. The method that works depends on your Docker setup.

Solution 1: Direct Bridge IP (config.tunnel-only.json) ✅ WORKING

Files:

• Dockerfile.tunnel-only
• docker-compose.tunnel-only.yml
• config.tunnel-only.json (updated to use 172.18.0.1:9090)

How it works:

• Uses the Docker bridge network IP directly
• You verified this works: curl 172.18.0.1:9090 ✅

Usage:

docker-compose -f docker-compose.tunnel-only.yml up --build

Config:

"service": "http://172.18.0.1:9090"

Solution 2: Host Network Mode (NEW - Recommended for Linux)

Files:

• Dockerfile.tunnel-only-v2
• docker-compose.tunnel-only-v2.yml
• config.tunnel-only-v2.json (uses localhost:9090)

How it works:

• Container runs in host network mode
• Can access localhost:9090 directly as if running on host

Usage:

docker-compose -f docker-compose.tunnel-only-v2.yml up --build

Config:

"service": "http://localhost:9090"

Note: Host network mode works best on Linux. May have limitations on Windows/Mac.

Quick Test Guide

1. Rebuild and restart with updated config (Solution 1)

# Stop current tunnel
docker-compose -f docker-compose.tunnel-only.yml down

# Rebuild with updated config (now uses 172.18.0.1)
docker-compose -f docker-compose.tunnel-only.yml up --build

2. Or try host network mode (Solution 2)

docker-compose -f docker-compose.tunnel-only-v2.yml up --build

Expected Success Output

INF Registered tunnel connection connIndex=0 connection=xxx event=0 ip=xxx location=bom protocol=http2
INF Registered tunnel connection connIndex=1 connection=xxx event=0 ip=xxx location=bom protocol=http2
INF Registered tunnel connection connIndex=2 connection=xxx event=0 ip=xxx location=bom protocol=http2
INF Registered tunnel connection connIndex=3 connection=xxx event=0 ip=xxx location=bom protocol=http2

No "Unable to reach the origin service" errors!

Test the Connection

From outside Docker (your current working test):

curl 172.18.0.1:9090
# Should return: Monaco Code Execution Server v1.0.0

From the tunnel (once running):

# Test via the public URL
curl https://api.ishikabhoyar.tech

Troubleshooting

If Solution 1 still doesn't work:

1. Check if Docker bridge IP changed:

   docker network inspect bridge | grep Gateway
   

2. Update config.tunnel-only.json with the correct IP

If Solution 2 doesn't work:

• Host network mode may not be fully supported on your OS
• Fall back to Solution 1 with correct bridge IP

Check tunnel logs:

docker-compose -f docker-compose.tunnel-only.yml logs -f

Verify backend is accessible from Docker:

docker run --rm alpine/curl:latest curl http://172.18.0.1:9090

Summary

Current Status: ✅ Config updated to use 172.18.0.1:9090

Next Step: Rebuild and restart the tunnel:

docker-compose -f docker-compose.tunnel-only.yml down
docker-compose -f docker-compose.tunnel-only.yml up --build

The tunnel should now successfully connect to your backend! 🎉