Setting Up Local SSL Certificates for Rails with Caddy

Developing web applications locally with HTTPS can be tricky, but Caddy makes it seamless. Caddy is a modern web server with automatic HTTPS built-in. In this guide, we'll cover how to use Caddy to:

✅ Serve a local Rails app over HTTPS
✅ Use a custom domain name for local development
✅ Set up reverse proxying with automatic SSL certificates

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🚀 Why Use Caddy for Local SSL?

While you can use tools like mkcert to create local certificates, Caddy simplifies the process by:

• Automatically generating and trusting certificates

• Handling reverse proxying and HTTPS termination

• Requiring minimal configuration with its Caddyfile

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📝 Step 1: Install Caddy

You can install Caddy easily via the instructions on the official website. On macOS with Homebrew:

brew install caddy

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🏗️ Step 2: Set Up Your Rails Server

Start your Rails server on port 3000 (the default development port):

rails server

Make sure it's running at http://localhost:3000.

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🖥️ Step 3: Configure a Custom Local Domain

To use a custom domain like myapp.local, you need to modify your hosts file:

Update /etc/hosts:

sudo nano /etc/hosts

Add the following line:

127.0.0.1 myapp.local

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🗄️ Step 4: Create a Caddyfile

Create a Caddyfile in your project root:

touch Caddyfile

Add the following content:

myapp.local {
    reverse_proxy localhost:3000
}

🔎 Explanation:

• myapp.local: The domain you set up in /etc/hosts.

• reverse_proxy localhost:3000: Proxies HTTPS requests to your Rails server running on port 3000.

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⚙️ Step 5: Run Caddy

Start Caddy with your configuration:

caddy run

Caddy will automatically issue a local SSL certificate for myapp.local and serve your Rails app over HTTPS.

🌐 Visit https://myapp.local to see your Rails app secured with HTTPS!

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🔒 Step 6 (Optional): Trust the Local Certificate

Some browsers or systems might not trust the automatically generated certificate. To trust it system-wide:

bashCopyEditcaddy trust

This command installs the generated root certificate into your system's trust store.

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🏎️ Alternative: One-Liner Reverse Proxy

If you don't want to use a Caddyfile, you can run:

caddy reverse-proxy --from myapp.local --to :3000

This achieves the same result but is more suitable for quick tests.

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🧪 Testing the Setup

1. Make sure Rails is running:

    rails server
   

2. Start Caddy with your Caddyfile:

    caddy run
   

3. Visit https://myapp.local in your browser.

🔐 You should now see your Rails app served over HTTPS with no certificate warnings!

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🎉 Conclusion

Using Caddy for local SSL in your Rails development environment provides a smooth, production-like setup. With automatic HTTPS and reverse proxying, you can focus on development without dealing with the complexities of certificate generation.