# Proxy with PHP

> Serve the MetricRaven script and events from one plain PHP file with curl.

Source: https://metricraven.com/docs/proxy-php  
Markdown: https://metricraven.com/docs/proxy-php.md  
Section: Proxy

One PHP file relays the script and events. It works on most shared hosting.

## Set it up

1. **Upload a.php to your web root**

   It needs PHP 7.4 or later with the `curl` extension, which most hosts enable.

   ```php title="a.php"
   <?php
   // a.php · plain PHP 7.4+ with the curl extension, next to your site's index.php
   $kind = $_GET['kind'] ?? '';
   $method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
   $isScript = $kind === 'script' && $method === 'GET';
   $isEvent = $kind === 'event' && $method === 'POST';
   if (!$isScript && !$isEvent) {
       http_response_code(404);
       exit;
   }

   // Behind a CDN or load balancer, REMOTE_ADDR is that proxy: use the header it sets instead.
   $headers = ['X-Visitor-IP: ' . $_SERVER['REMOTE_ADDR']];
   $forward = ['CONTENT_TYPE' => 'Content-Type', 'HTTP_ORIGIN' => 'Origin', 'HTTP_USER_AGENT' => 'User-Agent'];
   foreach ($forward as $key => $name) {
       if (!empty($_SERVER[$key])) $headers[] = $name . ': ' . $_SERVER[$key];
   }

   $ch = curl_init($isScript ? 'https://metricraven.com/js/script.js' : 'https://metricraven.com/api/v1/collect');
   curl_setopt_array($ch, [
       CURLOPT_RETURNTRANSFER => true,
       CURLOPT_HTTPHEADER => $headers,
       CURLOPT_TIMEOUT => 15,
       CURLOPT_ENCODING => '',
   ]);
   if ($isEvent) {
       curl_setopt($ch, CURLOPT_POST, true);
       curl_setopt($ch, CURLOPT_POSTFIELDS, file_get_contents('php://input'));
   }
   $body = curl_exec($ch);
   if ($body === false) {
       http_response_code(502);
       exit;
   }
   http_response_code(curl_getinfo($ch, CURLINFO_RESPONSE_CODE));
   header('Content-Type: ' . (curl_getinfo($ch, CURLINFO_CONTENT_TYPE) ?: 'application/octet-stream'));
   header('Cache-Control: ' . ($isScript ? 'public, max-age=3600' : 'no-store'));
   echo $body;
   ```

2. **Map /a/script and /a/event to it**

   On Apache, add this to the `.htaccess` in the same folder:

   ```apacheconf title=".htaccess"
   # .htaccess · Apache with mod_rewrite: serve a.php at /a/script and /a/event
   RewriteEngine On
   RewriteRule ^a/(script|event)$ a.php?kind=$1 [L,QSA]
   ```

   Can't use rewrites? Skip this step and use this tag instead of the one below:

   ```html
   <script
     defer
     src="/a.php?kind=script"
     data-api="/a.php?kind=event"
     data-site-id="YOUR_SITE_ID"
   ></script>
   ```

3. **Point your script tag at your own paths**

   Replace your MetricRaven tag with this one. `src` loads the tracker from your domain and `data-api` sends its events there too.

   ```html title="Your website's shared layout"
   <script defer src="/a/script" data-api="/a/event" data-site-id="YOUR_SITE_ID"></script>
   ```

> **Verify it works**
>
> Open your live site. In the browser's Network panel, `/a/script` loads the tracker and `/a/event` answers with `ok: true`. Nothing goes to `metricraven.com` from the browser.
>
> In **Traffic**, your own visit should show your real country and city. If every visit appears to come from your server's or host's location, the visitor IP isn't being forwarded.

## Notes

- If a CDN or load balancer sits in front of this server, the connecting address is that proxy, not the visitor. Use the visitor IP header it sets (and only one it overwrites, so visitors can't fake it).
- On WordPress, Laravel or another framework, prefer its own routing; see [Laravel](https://metricraven.com/docs/proxy-laravel).

How the proxy works and which headers it must send: [Use your own domain](https://metricraven.com/docs/proxy).

## Details

- The proxy forwards only `Content-Type`, `Origin`, `User-Agent` and the visitor's IP as `x-visitor-ip`. Your site's cookies and auth headers never leave your server.
- `Origin` matters: MetricRaven checks it against your site's allowed domains. A missing or wrong origin is refused with `domain_not_allowed`.
- MetricRaven allows about 120 events per minute per visitor IP. Without `x-visitor-ip`, all of your visitors share the proxy's IP, so busy sites lose events as well as locations.
- A proxy doesn't guarantee that every blocker will allow tracking.