self-host-101/caddy/readme.md

# Caddy Web Server and Reverse Proxy

**Caddy** is a web server that:
* Serves websites and web applications
* Can act as a [reverse proxy](https://en.wikipedia.org/wiki/Reverse_proxy)
* Automatically gets and renews TLS certificates so you get HTTPS for free!!

## Installation

Follow the official [Caddy Installation guide](https://caddyserver.com/docs/install#debian-ubuntu-raspbian) to install it.

To check if Caddy is installed and running 

```bash
sudo service caddy status
# You should see something like 
# active (running) 
```

Caddy is now running! By default, it listens on port 80 (HTTP). Visit your domain name in a browser - you should see Caddy's default welcome page.

Caddy's main config file is usually at `/etc/caddy/Caddyfile`.
This is where we will configure caddy web server.

## Setting up HTTPS for secure connection

**Pre Requisite**: Make sure domain's DNS A record points to your VPS IP address.
If you haven't done this yet, go back to the [VPS setup guide](../setup-vps.md) and complete the domain name section.

Open Caddy's config file

```bash
sudo vim /etc/caddy/Caddyfile
```

You'll see something like

```Caddyfile
:80 {
    root * /var/www/html
    file_server
}
```

Replace it with your domain name

```Caddyfile
domain.com {
    root * /var/www/html    # website files to server
    file_server             # enable static file server
}
```

Caddy will automatically get TLS certificate for `domain.com`.
We need not to worry about provisioning certificates or renewning them.

After making changes, reload Caddy configuration:

```bash
sudo systemctl reload caddy
```

Now visit `https://domain.com` (notice the `https`). HTTP traffic is secure and encrypted.

## Redirects

You probably want to redirect a few things:
* Visitors using `www.domain.com` -> redirect to `domain.com`
* Visitors using your server's IP address (`192.168.1.`) -> redirect to `domain.com`

```Caddyfile
192.168.1.1,
www.domain.com {
    redir https://domain.com{uri}
}
```

This config sets up the redirects as mentioned. You can list multiple domains/addresses separated by commas or spaces.
All visitors will end up at `https://yourdomain.com`, which looks clean imo!!!

Reload Caddy after making changes
```bash
sudo systemctl reload caddy
```

## Organizing Configuration

As we add more services, Caddyfile can get long and bloated. Caddy lets you split your configuration across multiple files!

### 1. Create the Config Directory

```bash
sudo mkdir -p /etc/caddy/conf.d
```

This directory will hold service specific config files, one file per service (e.g. `pokemon-api.Caddyfile`).

### 2. Update Main Caddyfile

Add this line in the main Caddyfile

```Caddyfile
import conf.d/*.Caddyfile
```

It will load all `.Caddyfile` files from the `conf.d` directory.
We can put each service's config in its own file!

Right now we don't have any specific service, but soon we will have.

## Custom Error Page

When something goes wrong, we can show a nice custom error page instead of Caddy's default.

There's a custom error page you can use [error.html](./error.html). It uses Caddy placeholders to show the error code and message.
Save it inside `/var/www` directory.

In your Caddyfile, add error_handler inside your domain block

```Caddyfile
domain.com {
    root * /var/www/html
    file_server

    handle_errors {
        root * /var/www
        rewrite * /error.html
        templates
        file_server
    }
}
```

* `handle_errors` - Catches all error responses
* `root * /var/www` - Specifies here to find the error.html file
* `rewrite * /error.html` - shows error.html for all errors
* `templates` - Enables Caddy's templating 

**To learn more** Check out [error handling](https://caddyserver.com/docs/caddyfile/directives/handle_errors) and [templates](https://caddyserver.com/docs/caddyfile/directives/templates) documentation

Reload caddy as usual

```bash
sudo systemctl reload caddy
```

## Reverse Proxy

Reverse proxy makes it easier to run multiple services running on one server without exposing multiple ports
We can have different subdomain for each service and reverse proxy will handle the routing.
When someone visits `pokemon.domain.com`, the reverse proxy looks at the request and forwards it to the correct service running on the server.

Let's say we have a pokemon API running on port 8080, and it should accessible at `pokemon.domain.com`.

### 1. Set Up DNS

In domain's DNS settings, create an A record
- **Name**: `pokemon` (for `pokemon.domain.com`)
- **Value**: Server's IP address

Wait for few minutes for DNS to propagate.

### 2. Create the Reverse Proxy Config

Create a new config file for the pokemon api

```bash
sudo vim /etc/caddy/conf.d/pokemon.Caddyfile
```

Add this block of configuration

```Caddyfile
pokemon.domain.com {
    reverse_proxy :8080
}
```


Reload Caddy

```bash
sudo systemctl reload caddy
```

Now visit `https://pokemon.domain.com` - Caddy will forward all traffic to your service and automatically get an HTTPS certificate for this domain.

I've included a template for reverse proxy block with error handling and redirects for `www` subdomain
Checkout the [`pokemon.Caddyfile`](./pokemon.Caddyfile) file. You can use as it as for setting up reverse proxies.

**To learn more** check out [reverse proxy](https://caddyserver.com/docs/quick-starts/reverse-proxy) documentation.