⚙️ Fly.io Deployment Guide for MCP Gateway¶

This guide covers the complete deployment workflow for the MCP Gateway on Fly.io, including common troubleshooting steps.

Overview¶

Fly.io is a global app platform for running containers close to your users, with built-in TLS, persistent volumes, and managed Postgres support. It offers a generous free tier and automatic HTTPS with fly.dev subdomains.

1 - Prerequisites¶

2 - Quick Start (Recommended)¶

2.1 Initialize Fly project¶

fly launch --name your-app-name --no-deploy

2.2 Create and attach Fly Postgres¶

# Create postgres (choose Development configuration for testing)
fly postgres create --name your-app-db --region yyz

# Note the connection details from the output, you'll need the password

2.3 Set secrets¶

# Set authentication secrets
fly secrets set JWT_SECRET_KEY=$(openssl rand -hex 32)
fly secrets set BASIC_AUTH_USER=admin BASIC_AUTH_PASSWORD=your-secure-password

# Set database URL (CRITICAL: use postgresql:// not postgres://)
fly secrets set DATABASE_URL="postgresql://postgres:YOUR_PASSWORD@your-app-db.flycast:5432/postgres"

⚠️ Important: Always use postgresql:// scheme, not postgres://. The latter causes SQLAlchemy dialect loading errors.

2.4 Deploy the app¶

fly deploy

3 - Containerfile Requirements¶

Ensure your Containerfile explicitly installs PostgreSQL dependencies:

# Create virtual environment, upgrade pip and install dependencies
RUN python3 -m venv /app/.venv && \
/app/.venv/bin/python3 -m pip install --upgrade pip setuptools pdm uv && \
/app/.venv/bin/python3 -m pip install psycopg2-binary && \
/app/.venv/bin/python3 -m uv pip install ".[redis]"

The explicit psycopg2-binary installation is required because uv may not properly install optional dependencies.

4 - fly.toml Configuration¶

Your fly.toml should look like this:

app = "your-app-name"
primary_region = "yyz"

[build]
dockerfile = "Containerfile"

[env]
HOST = "0.0.0.0"
PORT = "4444"

[http_service]
internal_port = 4444
force_https = true
auto_stop_machines = "stop"
auto_start_machines = true
min_machines_running = 0
processes = ["app"]

[[vm]]
memory = "1gb"
cpu_kind = "shared"
cpus = 1

Note: Don't put secrets like DATABASE_URL in fly.toml - use fly secrets set instead.

5 - Testing Your Deployment¶

5.1 Check app status¶

fly status
fly logs

5.2 Test endpoints¶

# Health check (no auth required)
curl https://your-app-name.fly.dev/health

# Protected endpoints (require auth)
curl -u admin:your-password https://your-app-name.fly.dev/docs
curl -u admin:your-password https://your-app-name.fly.dev/tools

5.3 Expected responses¶

• Health: {"status":"healthy"}
• Protected endpoints without auth: {"detail":"Not authenticated"}
• Protected endpoints with auth: JSON response with data

6 - Troubleshooting¶

Common Issue 1: SQLAlchemy postgres dialect error¶

sqlalchemy.exc.NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:postgres

Solutions: 1. Ensure psycopg2-binary is explicitly installed in Containerfile 2. Use postgresql:// not postgres:// in DATABASE_URL 3. Rebuild with fly deploy --no-cache

Common Issue 2: Database connection refused¶

Solutions: 1. Verify DATABASE_URL format: postgresql://postgres:PASSWORD@your-db.flycast:5432/postgres 2. Check postgres app is running: fly status -a your-app-db 3. Verify password matches postgres creation output

Common Issue 3: Machines not updating¶

Solutions:

# Force machine updates
fly machine list
fly machine update MACHINE_ID --image your-new-image

# Or restart all machines
fly scale count 0
fly scale count 1

7 - Production Considerations¶

Security¶

• Change default BASIC_AUTH_PASSWORD to a strong password
• Consider using JWT tokens for API access
• Enable Fly's private networking for database connections

Scaling¶

# Scale to multiple machines for HA
fly scale count 2

# Scale machine resources
fly scale memory 2gb

Monitoring¶

# View real-time logs
fly logs -f

# Check machine metrics
fly machine status MACHINE_ID

8 - Clean Deployment Script¶

For a completely fresh deployment:

#!/bin/bash
set -e

APP_NAME="your-app-name"
DB_NAME="${APP_NAME}-db"
REGION="yyz"
PASSWORD=$(openssl rand -base64 32)

echo "🚀 Deploying MCP Gateway to Fly.io..."

# Create app
fly launch --name $APP_NAME --no-deploy --region $REGION

# Create postgres
fly postgres create --name $DB_NAME --region $REGION

# Set secrets
fly secrets set JWT_SECRET_KEY=$(openssl rand -hex 32)
fly secrets set BASIC_AUTH_USER=admin
fly secrets set BASIC_AUTH_PASSWORD=$PASSWORD

# Get postgres password and set DATABASE_URL
echo "⚠️  Set your DATABASE_URL manually with the postgres password:"
echo "fly secrets set DATABASE_URL=\"postgresql://postgres:YOUR_PG_PASSWORD@${DB_NAME}.flycast:5432/postgres\""

# Deploy
echo "🏗️  Ready to deploy. Run: fly deploy"

9 - Additional Resources¶

• Fly.io Documentation
• Fly Postgres Guide
• Fly Secrets Management

Success indicators: - ✅ fly status shows machines as "started" - ✅ /health endpoint returns {"status":"healthy"} - ✅ Protected endpoints require authentication - ✅ No SQLAlchemy errors in logs