# Configuration Overview (/configuration)



Rustinx uses a single TOML file for all configuration. By default, it looks for `/etc/rustinx/rustinx.toml`. You can change this with the `--config` flag.

## Config Structure [#config-structure]

A Rustinx config file has four sections:

```toml title="rustinx.toml"
# Server-level settings
[server]
listen = "0.0.0.0:9090"

# Access logging
[logging]
enabled = false

# Default settings for all virtual hosts
[defaults]
block_dot_paths = true

# Virtual hosts (one or more)
[[vhost]]
hostnames = ["mysite.com"]
root = "/static"
```

## Minimal Config [#minimal-config]

The smallest useful config file:

```toml title="rustinx.toml"
[[vhost]]
hostnames = ["_"]
root = "/static"
```

This serves files from `/static` on port 9090, matching any hostname. All security defaults are applied automatically.

## How Defaults Work [#how-defaults-work]

The `[defaults]` section sets values that apply to every virtual host. Each vhost can override these values.

```toml title="rustinx.toml"
[defaults]
block_dot_paths = true
etag = true
allowed_methods = ["GET", "HEAD"]

[defaults.headers]
X-Content-Type-Options = "nosniff"
X-Frame-Options = "DENY"

# This vhost inherits all defaults
[[vhost]]
hostnames = ["site-a.com"]
root = "/static/site-a"

# This vhost overrides X-Frame-Options
[[vhost]]
hostnames = ["site-b.com"]
root = "/static/site-b"

[vhost.headers]
X-Frame-Options = "SAMEORIGIN"
```

## Config Validation [#config-validation]

Rustinx validates the entire config file at startup. If anything is wrong, it prints a clear error and exits before serving any traffic.

Things that are checked:

* All hostnames are valid DNS names
* No duplicate hostnames across vhosts
* All file paths are safe (no `..`, no dotfiles, no absolute paths in targets)
* Security headers have valid values
* Redirect URLs are safe (HTTPS only, no protocol-relative, no credentials)
* Server limits are within bounds
* Root directories exist and are accessible
* Unknown config keys are rejected (catches typos)

```shell
$ rustinx --config bad.toml
[rustinx] config error: method 'OPTIONS' not supported — only GET and HEAD are valid for static serving
```

## Unknown Fields [#unknown-fields]

Rustinx rejects unknown config keys. This catches typos that could silently disable security features:

```toml
[server]
max_connectionz = 5  # typo: should be max_connections
```

```ansi
[rustinx] config error: parse config: unknown field `max_connectionz`
```