feat: web healthcheck returns 503 status code if database is unavailable

docker-compose.yml

@@ -33,12 +33,11 @@ services:
     ports:
       - "8081:80"
     depends_on:
-      data_handler:
+      db:
         condition: service_started
     # all the way zoomed out, with hamburg at the center, at least one camera should be returned
     healthcheck:
-      test: >
-        ["CMD", "curl -s 'http://localhost/camera.php?bbox=-92.52991540527346,30.683278176916133,131.7689595947266,72.87186315234298&zoom=4&width=2552&height=867' | grep '^\[.+\]$'"]
+      test: ["CMD", "curl", "-f", "http://localhost/sync-state.php"]
       interval: 10s
       timeout: 5s
       start_period: 30s

web/www/sunders/sync-state.php

@@ -6,8 +6,9 @@
   /* Connect to database */
   $mysqli = new mysqli(MYSQL_HOST, MYSQL_USER, MYSQL_PASSWORD, MYSQL_DB);
   if($mysqli->connect_errno) {
+    http_response_code(503);
     header('Content-type: application/json');
-    $result = '{"error":"error while connecting to db : ' . $mysqli->error . '"}';
+    $result = '{"error":"Database unavailable"}';
     echo $result;
     exit;
   }