fix OOM kills: tune MySQL memory, reduce Nextcloud workers, increase Uptime Kuma limit

MySQL (3 OOM kills):
- Cap group_replication_message_cache_size to 128MB (default 1GB caused OOM)
- Reduce innodb_log_buffer_size from 64MB to 16MB
- Lower max_connections from 151 to 80 (peak usage ~40)
- Increase memory limit from 3Gi to 4Gi for headroom

Nextcloud (30+ apache2 OOM kills per incident):
- Reduce MaxRequestWorkers from 50 to 10 to prevent fork bomb
  when SQLite locks cause request pileup
- Lower StartServers/MinSpare/MaxSpare proportionally

Uptime Kuma (Node.js memory leak):
- Increase memory limit from 256Mi to 512Mi
- Increase CPU limit from 200m to 500m

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

stacks/nextcloud/main.tf

@@ -1,9 +1,9 @@
 variable "tls_secret_name" {
-  type = string
+  type      = string
   sensitive = true
 }
 variable "nextcloud_db_password" {
-  type = string
+  type      = string
   sensitive = true
 }
 variable "nfs_server" { type = string }
@@ -93,15 +93,15 @@ resource "kubernetes_config_map" "apache_tuning" {
   }
   data = {
     "mpm_prefork.conf" = <<-EOF
-      # Tuned for container with 6Gi memory limit
-      # Each worker uses ~220MB RSS, so 50 workers ≈ 11GB (shared pages reduce actual)
-      # Need enough workers so probes can get through during SQLite locks
+      # Tuned for container with 6Gi memory limit and SQLite backend
+      # Each worker uses ~100-200MB RSS. 10 workers = ~2GB max
+      # Low count prevents fork bomb when SQLite locks cause request pileup
       <IfModule mpm_prefork_module>
-        StartServers            5
-        MinSpareServers         3
-        MaxSpareServers         10
-        MaxRequestWorkers       50
-        MaxConnectionsPerChild  200
+        StartServers            3
+        MinSpareServers         2
+        MaxSpareServers         5
+        MaxRequestWorkers       10
+        MaxConnectionsPerChild  100
       </IfModule>
     EOF
   }
@@ -223,12 +223,12 @@ module "ingress" {
   port            = 8080
   rybbit_site_id  = "5a3bfe59a3fe"
   extra_annotations = {
-    "gethomepage.dev/enabled"        = "true"
-    "gethomepage.dev/name"           = "Nextcloud"
-    "gethomepage.dev/description"    = "Cloud productivity suite"
-    "gethomepage.dev/icon"           = "nextcloud.png"
-    "gethomepage.dev/group"          = "Productivity"
-    "gethomepage.dev/pod-selector"   = ""
+    "gethomepage.dev/enabled"         = "true"
+    "gethomepage.dev/name"            = "Nextcloud"
+    "gethomepage.dev/description"     = "Cloud productivity suite"
+    "gethomepage.dev/icon"            = "nextcloud.png"
+    "gethomepage.dev/group"           = "Productivity"
+    "gethomepage.dev/pod-selector"    = ""
     "gethomepage.dev/widget.type"     = "nextcloud"
     "gethomepage.dev/widget.url"      = "https://nextcloud.viktorbarzin.me"
     "gethomepage.dev/widget.username" = var.homepage_credentials["nextcloud"]["username"]

stacks/platform/modules/dbaas/main.tf

@@ -171,6 +171,12 @@ resource "helm_release" "mysql_cluster" {
         group_replication_member_expel_timeout=30
         group_replication_unreachable_majority_timeout=60
         group_replication_start_on_boot=ON
+        # Cap XCom cache to prevent unbounded growth (default 1GB causes OOM)
+        group_replication_message_cache_size=134217728
+        # Reduce log buffer (16MB sufficient for this workload, was 64MB)
+        innodb_log_buffer_size=16777216
+        # Limit connections (peak usage ~40, no need for 151)
+        max_connections=80
       EOT
     }
 
@@ -181,7 +187,7 @@ resource "helm_release" "mysql_cluster" {
       }
       limits = {
         cpu    = "2"
-        memory = "3Gi"
+        memory = "4Gi"
       }
     }
 

stacks/platform/modules/uptime-kuma/main.tf

@@ -71,8 +71,8 @@ resource "kubernetes_deployment" "uptime-kuma" {
               memory = "64Mi"
             }
             limits = {
-              cpu    = "200m"
-              memory = "256Mi"
+              cpu    = "500m"
+              memory = "512Mi"
             }
           }