From 73ac554add77992ece9ab7550122d9cf720578fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Taylan=20Bak=C4=B1rc=C4=B1o=C4=9Flu?= <taylanb@outlook.com>
Date: Mon, 17 Nov 2025 10:09:05 +0300
Subject: [PATCH] fix(backend): Skip backends with no servers in HAProxy config
 generation
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CRITICAL FIX: Backends without servers were causing HAProxy validation failures

Problem:
- Backend 'silbeni' (ID: 118) oluşturuldu ama server eklenmedi
- Config generator backend'i haproxy.cfg'ye yazdı ama server satırı olmadan
- HAProxy validation FAIL: 'backend has no servers'
- Agent config'i apply etmedi
- Frontend'de backend görünmedi (validation fail nedeniyle)

Root Cause:
- Config generator server olup olmadığını kontrol etmiyordu
- HAProxy en az 1 server gerektirir, yoksa validation fail olur
- Validation fail = agent apply etmez = backend haproxy.cfg'de görünmez

Solution:
- Backend loop başında server pre-check eklendi
- Server yoksa backend config'e yazılmaz ve WARNING log'lanır
- HAProxy validation her zaman başarılı olur (sadece valid backend'ler yazılır)

Impact:
✅ Server olmayan backend'ler artık config'e yazılmayacak
✅ HAProxy validation artık fail olmayacak
✅ Agent successfully apply edecek
✅ Kullanıcı frontend'de backend'i görecek (0/0 servers ⚠️ Empty tag ile)
✅ Kullanıcı server ekledikten sonra Apply yapınca backend haproxy.cfg'ye yazılacak

Testing:
- Server olmayan backend oluştur → Config'e yazılmaz (log: SKIPPING)
- Server ekle → Config'e yazılır
- Apply → Başarılı

Related: a39a5d6 (frontend null/undefined check)
Refs: #backend-validation #haproxy-config-generator
---
 backend/services/haproxy_config.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/backend/services/haproxy_config.py b/backend/services/haproxy_config.py
index 919ad80..0ceba1f 100644
--- a/backend/services/haproxy_config.py
+++ b/backend/services/haproxy_config.py
@@ -441,6 +441,19 @@ async def generate_haproxy_config_for_cluster(cluster_id: int, conn: Optional[An
                 logger.error("Backend with missing name detected - skipping")
                 continue
             
+            # CRITICAL PRE-CHECK: Get servers BEFORE starting backend config
+            # This allows us to skip backends with no servers before writing anything
+            # CRITICAL FIX: Handle servers with NULL cluster_id (legacy data)
+            # CRITICAL: Select ssl_certificate_id for SSL ca-file path generation
+            servers_precheck = await db_conn.fetch("""
+                SELECT id FROM backend_servers 
+                WHERE backend_name = $1 AND (cluster_id = $2 OR cluster_id IS NULL) AND is_active = TRUE
+            """, backend["name"], cluster_id)
+            
+            if not servers_precheck or len(servers_precheck) == 0:
+                logger.warning(f"⚠️  CONFIG GENERATION: Skipping backend '{backend['name']}' - NO ACTIVE SERVERS. HAProxy requires at least one server per backend.")
+                continue
+            
             config_lines.append(f"backend {backend['name']}")
             
             # --- HAProxy Configuration Best Practice Order ---