Tune Zabbix stack: PostgreSQL, web PHP-FPM, server caches

PostgreSQL 16:
- shared_buffers 128MB→256MB, work_mem 4MB→16MB
- random_page_cost 4→1.1 (SSD/Longhorn), effective_io_concurrency→200
- maintenance_work_mem→128MB, wal_buffers→8MB
- max_connections 100→50, memory limit 512Mi→1Gi

Zabbix Web:
- PHP_FPM_PM_MAX_CHILDREN 50→10 (fixes 68x OOMKill)
- ZBX_MEMORYLIMIT 128M→256M, PM_MAX_REQUESTS→500
- Memory limit 512Mi→768Mi, request 128Mi→256Mi

Zabbix Server:
- ZBX_CACHESIZE→64M, ZBX_VALUECACHESIZE→64M
- ZBX_HISTORYCACHESIZE→32M, ZBX_TRENDCACHESIZE→8M
- ZBX_STARTPOLLERS→10, ZBX_STARTPOLLERSUNREACHABLE→3

apps/zabbix/zabbix.yaml

@@ -32,6 +32,25 @@ spec:
       containers:
         - name: postgres
           image: postgres:16-alpine
+          args:
+            - "-c"
+            - "shared_buffers=256MB"
+            - "-c"
+            - "effective_cache_size=512MB"
+            - "-c"
+            - "work_mem=16MB"
+            - "-c"
+            - "maintenance_work_mem=128MB"
+            - "-c"
+            - "random_page_cost=1.1"
+            - "-c"
+            - "effective_io_concurrency=200"
+            - "-c"
+            - "max_connections=50"
+            - "-c"
+            - "checkpoint_completion_target=0.9"
+            - "-c"
+            - "wal_buffers=8MB"
           ports:
             - containerPort: 5432
               name: postgres
@@ -54,11 +73,11 @@ spec:
               subPath: pgdata
           resources:
             requests:
-              memory: 256Mi
-              cpu: 100m
-            limits:
               memory: 512Mi
-              cpu: 500m
+              cpu: 200m
+            limits:
+              memory: 1Gi
+              cpu: "1"
           livenessProbe:
             exec:
               command:
@@ -139,6 +158,18 @@ spec:
                   key: DB-Password
             - name: POSTGRES_DB
               value: zabbix
+            - name: ZBX_CACHESIZE
+              value: "64M"
+            - name: ZBX_VALUECACHESIZE
+              value: "64M"
+            - name: ZBX_HISTORYCACHESIZE
+              value: "32M"
+            - name: ZBX_TRENDCACHESIZE
+              value: "8M"
+            - name: ZBX_STARTPOLLERS
+              value: "10"
+            - name: ZBX_STARTPOLLERSUNREACHABLE
+              value: "3"
           resources:
             requests:
               memory: 256Mi
@@ -239,12 +270,24 @@ spec:
                 secretKeyRef:
                   name: zabbix-credentials
                   key: password
+            - name: ZBX_MEMORYLIMIT
+              value: "256M"
+            - name: PHP_FPM_PM_MAX_CHILDREN
+              value: "10"
+            - name: PHP_FPM_PM_START_SERVERS
+              value: "3"
+            - name: PHP_FPM_PM_MIN_SPARE_SERVERS
+              value: "2"
+            - name: PHP_FPM_PM_MAX_SPARE_SERVERS
+              value: "5"
+            - name: PHP_FPM_PM_MAX_REQUESTS
+              value: "500"
           resources:
             requests:
-              memory: 128Mi
-              cpu: 50m
+              memory: 256Mi
+              cpu: 100m
             limits:
-              memory: 512Mi
+              memory: 768Mi
               cpu: 500m
           livenessProbe:
             httpGet: