scrutiny/docs/TROUBLESHOOTING_REVERSE_PROXY.md

# Reverse Proxy Support

Scrutiny is designed so that it can be used with a reverse proxy, leveraging `domain`, `port` or `path` based matching to correctly route to the Scrutiny service.

For simple `domain` and/or `port` based routing, this is easy.

If your domain:port pair is similar to `http://scrutiny.example.com` or `http://localhost:54321`, just update your reverse proxy configuration
to route traffic to the Scrutiny backend, which is listening on `0.0.0.0:8080` by default.

```yaml
# default config
web:
  listen:
    port: 8080
    host: 0.0.0.0
```

However if you're using `path` based routing to differentiate your reverse proxy protected services, things become more complicated.

If you'd like to access Scrutiny using a path like: `http://example.com/scrutiny/`, then we need a way to configure Scrutiny so that it
understands `http://example.com/scrutiny/api/health` actually means `http://localhost:8080/api/health`.

Thankfully this can be done by changing **two** settings (both are required).

1. The webserver has a `web.listen.basepath` key
2. The collectors have a `api.endpoint` key.

## Webserver Configuration

When setting the `web.listen.basepath` key in the web config file, make sure the `basepath` key is prefixed with `/`.

```yaml
# customized webserver config
web:
  listen:
    port: 8080
    host: 0.0.0.0
    # if you're using a reverse proxy like apache/nginx, you can override this value to serve scrutiny on a subpath.
    # eg. http://example.com/custombasepath/* vs http://example.com:8080
    basepath: '/custombasepath'
```

## Collector Configuration 

Here's how you can update the collector `api.endpoint` key:

```yaml
# customized collector config
api:
  endpoint: 'http://localhost:8080/custombasepath'
```

# Environmental Variables.

You may also configure these values using the following environmental variables (both are required).

- `COLLECTOR_API_ENDPOINT=http://localhost:8080/custombasepath`
- `SCRUTINY_WEB_LISTEN_BASEPATH=/custombasepath`

# Real Examples

## Caddy

1. Create a Caddyfile
    ```yaml
    # Caddyfile
    :9090
    
    # The `scrutiny` text in this file must match the service name in the docker-compose file below. 
    # The `/custom/` text is the custom base path scrutiny will be availble on. 
    reverse_proxy /custom/* scrutiny:8080

    ```
2. Create a `docker-compose.yml` file

    ```yaml
    # docker-compose.yml
    version: '3.5'
    
    services:
      scrutiny:
        container_name: scrutiny
        image: ghcr.io/analogj/scrutiny:master-omnibus
        cap_add:
          - SYS_RAWIO
        ports:
          - "8086:8086" # influxDB admin
        volumes:
          - /run/udev:/run/udev:ro
          - ./config:/opt/scrutiny/config
          - ./influxdb:/opt/scrutiny/influxdb
        devices:
          - "/dev/sda"
          - "/dev/sdb"
        environment:
          - SCRUTINY_WEB_LISTEN_BASEPATH=/custom
          - COLLECTOR_API_ENDPOINT=http://localhost:8080/custom
      caddy:
        image: caddy
        volumes:
          - ./Caddyfile:/etc/caddy/Caddyfile
        ports:
          - "9090:9090"
    ```
3. run `docker-compose up`
4. visit [http://localhost:9090/custom/web](http://localhost:9090/custom/web) - access the scrutiny container via caddy reverse proxy