add metrics

metrics.php

@@ -0,0 +1,41 @@
+<?php
+
+header('Content-Type: application/json; charset=utf-8');
+
+if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
+    http_response_code(405);
+    header('Allow: GET');
+    echo json_encode(['error' => 'method not allowed']);
+    exit;
+}
+
+function get_snowflake_connections()
+{
+    $metric = 'tor_snowflake_proxy_connections_total';
+    $body = file_get_contents(
+        'http://127.0.0.1:9999/internal/metrics',
+        false
+    );
+    if (!$body) {
+        return 0;
+    }
+    $conns = 0;
+    foreach (preg_split('/\r\n|\n|\r/', $body) as $line) {
+        $line = trim($line);
+        if (!$line || $line[0] === '#')
+            continue;
+        if (preg_match(
+            '/^'
+                . preg_quote($metric, '/')
+                . '(?:\{[^}]*\})?\s+([0-9]+(?:\.[0-9]+)?)$/', $line, $m
+        )) {
+            $conns = $m[1];
+            break;
+        }
+    }
+    return $conns;
+}
+
+$snowflake_connections = get_snowflake_connections();
+
+echo json_encode(['snowflake_connections' => $snowflake_connections]);