Massed Compute

WebSocket connections require special proxy handling because they use an HTTP Upgrade handshake to switch from HTTP to the ws:// protocol. A standard HTTP proxy will break this handshake, but Nginx can forward the Upgrade header properly to maintain persistent connections.

This configuration supports Socket.IO applications, MQTT-over-WebSocket brokers, real-time chat applications, and any WebSocket server that needs to be accessible through a proxy layer.

Massed Compute VM Pricing

Step-by-Step Deployment

# Using Massed Compute CLI
mc instances launch \
  --name websocket-proxy \
  --image ubuntu-22.04 \
  --sku cpu_mini_amd_epyc \
  --ssh-key your-key-name

ssh ubuntu@YOUR_VM_IP

sudo apt-get update
sudo apt-get install -y nginx

# Install websocat for WebSocket testing
sudo wget -O /usr/local/bin/websocat https://github.com/vi/websocat/releases/download/v1.13.0/websocat.x86_64-unknown-linux-musl
sudo chmod +x /usr/local/bin/websocat

# Create the proxy configuration
sudo tee /etc/nginx/sites-available/wsproxy <<EOF
map \$http_upgrade \$connection_upgrade {
    default upgrade;
    '' close;
}

server {
    listen 80 default_server;
    listen [::]:80 default_server;

    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade \$http_upgrade;
        proxy_set_header Connection \$connection_upgrade;
        proxy_set_header Host \$host;
        proxy_set_header X-Real-IP \$remote_addr;
        proxy_set_header X-Forwarded-For \$proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto \$scheme;

        # Long timeouts for WebSocket connections
        proxy_read_timeout 3600s;
        proxy_send_timeout 3600s;
    }
}
EOF

# Remove default site
sudo rm /etc/nginx/sites-enabled/default

# Enable WebSocket proxy site
sudo ln -s /etc/nginx/sites-available/wsproxy /etc/nginx/sites-enabled/

# Test configuration
sudo nginx -t

# Restart Nginx
sudo systemctl restart nginx
sudo systemctl enable nginx

# Start a simple WebSocket echo server on port 3000
websocat -s 127.0.0.1:3000 &

# Test WebSocket connection through proxy
echo "Hello WebSocket" | websocat ws://YOUR_VM_IP/

# Should echo back: Hello WebSocket

# Install Certbot
sudo apt-get install -y certbot python3-certbot-nginx

# Get SSL certificate (replace example.com)
sudo certbot --nginx -d your-domain.com

# Certbot will automatically update Nginx config for HTTPS

Troubleshooting

WebSocket Connection Fails

If WebSocket connections fail to establish, check the Nginx error log and verify the upstream service is running:

# Check Nginx error logs
sudo tail -f /var/log/nginx/error.log

# Verify upstream service is listening
netstat -tlnp | grep :3000

# Test direct connection to upstream
echo "test" | websocat ws://127.0.0.1:3000/

Connection Drops After Idle Time

If connections drop during idle periods, increase the proxy timeouts or add keepalive settings:

# Add to location block in Nginx config
proxy_read_timeout 7200s;
proxy_send_timeout 7200s;
proxy_connect_timeout 60s;

SSL Certificate Issues

For wss:// connections, ensure your SSL certificate covers the domain and Nginx is configured for HTTPS:

# Check SSL certificate status
sudo certbot certificates

# Test SSL configuration
nginx -t

# Verify HTTPS is working
curl -I https://your-domain.com

Skip All of This: Deploy with an AI Agent

This entire guide exists as a tested, machine-readable recipe in the Massed Compute MCP. Instead of running these commands manually, connect an AI agent with MCP support:

{
  "mcpServers": {
    "massed-compute": {
      "type": "http",
      "url": "https://vm.massedcompute.com/api/mcp",
      "headers": { "Authorization": "Bearer MC_TOKEN" }
    }
  }
}

Then say:

The agent matches your request against the recipe catalog, provisions the right VM shape, runs the setup and verification steps above, and reports back with the connection details. If any step fails, the deployment stops and reports the specific error.

Recipe last tested: May 29, 2026

Quick Setup Guide

For experienced users, here’s the condensed version:

# 1. Launch VM and connect
mc instances launch --name ws-proxy --image ubuntu-22.04 --sku cpu_mini_amd_epyc
ssh ubuntu@VM_IP

# 2. Install and configure
sudo apt-get update && sudo apt-get install -y nginx
sudo wget -O /usr/local/bin/websocat https://github.com/vi/websocat/releases/download/v1.13.0/websocat.x86_64-unknown-linux-musl
sudo chmod +x /usr/local/bin/websocat

# 3. Create proxy config
sudo tee /etc/nginx/sites-available/wsproxy <<EOF
map \$http_upgrade \$connection_upgrade {
    default upgrade;
    '' close;
}

server {
    listen 80 default_server;
    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade \$http_upgrade;
        proxy_set_header Connection \$connection_upgrade;
        proxy_read_timeout 3600s;
        proxy_send_timeout 3600s;
    }
}
EOF

# 4. Enable and test
sudo rm /etc/nginx/sites-enabled/default
sudo ln -s /etc/nginx/sites-available/wsproxy /etc/nginx/sites-enabled/
sudo systemctl restart nginx

Frequently Asked Questions