fix: return HTTP 503 on bootstrap error for /health endpoint

[kayjoosten]

Summary

• Wraps the env validation block in public/index.php in a try-catch(\Throwable) so misconfiguration errors (e.g. missing/short APP_SECRET) return HTTP 503 instead of a PHP fatal error page with HTTP 200
• Response format matches the openconext/monitor-bundle DOWN convention: {"status":"DOWN","message":"..."}
• Adds error_log() so bootstrap failures still appear in server logs
• Adds functional test coverage for the public /health route

Test Plan

• Set APP_ENV=prod and APP_SECRET=short in devconf .env, restart engine container, hit GET https://engine.dev.openconext.local/health — expect HTTP 503 with {"status":"DOWN","message":"APP_SECRET must be at least 32 characters long in production."}
• Revert .env, restart, hit /health again — expect HTTP 200 {"status":"UP"}
• Run ./vendor/bin/phpunit --configuration=./tests/phpunit.xml --testsuite=functional --filter=MonitorControllerTest — expect 3 tests passing

Closes #1936

[johanib]

Did some digging. Your change seems the best solution 👍
Not really nice or elegant. But it works and I think its the only way.

One suggestion in the code, and maybe it's a good idea to also intercept errors in the regular fallback handler. Otherwise, in some scenario's the fallback might hijack errors, and do a 301 redirect instead of returning a 500 on the health endpoints..

Index: src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php b/src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php
--- a/src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php	(revision 1cdd470e6c39b94a9a7344e3a471010344487772)
+++ b/src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php	(date 1775571383912)
@@ -21,6 +21,7 @@
 use EngineBlock_Exception;
 use OpenConext\EngineBlockBridge\ErrorReporter;
 use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpKernel\Event\ExceptionEvent;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
@@ -76,6 +77,15 @@
             $exception->getMessage()
         ));
 
+        $path = $event->getRequest()->getPathInfo();
+        if (in_array($path, ['/health', '/internal/health', '/info', '/internal/info'], true)) {
+            $event->setResponse(new JsonResponse(
+                ['status' => 'DOWN', 'message' => $exception->getMessage()],
+                JsonResponse::HTTP_SERVICE_UNAVAILABLE
+            ));
+            return;
+        }
+
         if ($exception instanceof EngineBlock_Exception) {
             $this->errorReporter->reportError($exception, 'Caught Unhandled EngineBlock_Exception');
         } else {

[johanib]

Maybe include everything up to and including Request::createFromGlobals() into the try?
Wdyt?