Add the memcached plugin (object caching)

docker/wp-config.php

@@ -126,7 +126,6 @@ define('AUTH_SALT',         $noblogs_config['secrets']['auth_salt']);
 define('SECURE_AUTH_SALT',  $noblogs_config['secrets']['secure_auth_salt']);
 define('LOGGED_IN_SALT',    $noblogs_config['secrets']['logged_in_salt']);
 define('NONCE_SALT',        $noblogs_config['secrets']['nonce_salt']);
-define('WP_CACHE_KEY_SALT', $noblogs_config['secrets']['wp_cache_key_salt']);
 
 /**#@-*/
 
@@ -181,6 +180,18 @@ if (array_key_exists('debug_cookie_name', $noblogs_config) &&
         define('WP_DEBUG', true);
         define('WP_DEBUG_LOG', true);
         define('WP_DEBUG_DISPLAY', false);
+
+    // Warning handler that dumps stack traces.
+    class WarningWithStacktrace extends ErrorException {}
+    set_error_handler(function($severity, $message, $file, $line) {
+        if ($severity & (E_WARNING | E_NOTICE | E_USER_WARNING | E_USER_NOTICE)) {
+            $ex = new WarningWithStacktrace($message, 0, $severity, $file, $line);
+            error_log("\n" . $ex. "\n");
+            return true;
+        } 
+        return false;
+    });
+
 } else {
     define('WP_DEBUG', false);
 }