feat(minecraft-java): auto-size JVM heap from the container memory limit (2.7.0)

minecraft-java/README.md

@@ -38,13 +38,21 @@ chosen file downloads through the same allowlist (Modrinth's CDN is listed).
 
 ## Memory / JVM heap
 
-The wizard's **JVM max heap** / **JVM initial heap** fields (configSchema
-`MAX_MEMORY` / `INIT_MEMORY`, defaults `2G` / `1G`) size the Java heap via
-the itzg image's `-Xmx`/`-Xms` plumbing. Keep the max heap roughly **25%
-below the container memory limit**: the limit only caps the cgroup — it
-does not size the heap — so a heap at or above the limit gets the server
-OOM-killed, and a limit far above the heap wastes RAM the JVM will never
-touch.
+Left empty (the default), the wizard's **JVM max heap** / **JVM initial
+heap** fields (configSchema `MAX_MEMORY` / `INIT_MEMORY`) are sized
+automatically to **75% of the container memory limit** — pick 8Gi of
+memory and the heap becomes 6144M, and it re-tracks the limit whenever
+you resize the server. The remaining 25% is headroom for non-heap JVM
+memory: the limit only caps the cgroup — it does not size the heap — so
+a heap at or above the limit gets the server OOM-killed, and a limit far
+above the heap wastes RAM the JVM will never touch. Automatic sizing
+needs gameplane ≥ 0.2.0-beta.6 (`gameplaneMinVersion` gates this bundle
+accordingly).
+
+Setting either field explicitly (e.g. `2G`, `3072M`) turns the automatic
+sizing off for that field and feeds the value straight to the itzg
+image's `-Xmx`/`-Xms` plumbing; keep an explicit max heap roughly 25%
+below the container limit for the same reason.
 
 ## Logs (including install)
 

minecraft-java/module.yaml

@@ -1,9 +1,9 @@
 apiVersion: gameplane.local/module/v1
 name: minecraft-java
 displayName: Minecraft (Java Edition)
-version: 2.6.0
+version: 2.7.0
 game: minecraft-java
 summary: Vanilla / Paper / Spigot / Bukkit / Purpur / Forge / NeoForge / Fabric / Quilt servers (itzg/minecraft-server) with a version+loader picker spanning 1.16.5–latest, per-loader mod volumes, and in-app Modrinth browse.
 homepage: https://www.minecraft.net/
 license: MIT
-gameplaneMinVersion: 0.2.0
+gameplaneMinVersion: 0.2.0-beta.6

minecraft-java/template.yaml

@@ -519,22 +519,31 @@ spec:
       type: int
       default: "10"
 
-    # The itzg image passes these to the JVM as -Xms/-Xmx. They must track
-    # the container memory limit: the limit only caps the cgroup, it does
-    # NOT size the heap, so a 3Gi limit with the old hardcoded 2G heap
-    # wasted a gigabyte — and a limit *below* heap + JVM overhead got the
-    # container OOM-killed.
+    # The itzg image passes these to the JVM as -Xms/-Xmx. Left empty,
+    # the operator sizes both to 75% of the container memory limit
+    # (autoFromMemoryLimit — needs gameplane ≥ 0.2.0-beta.6; the
+    # remaining 25% is headroom for non-heap JVM memory, which is what
+    # keeps the cgroup from OOM-killing the server). Equal -Xms/-Xmx
+    # gives a fixed heap, which game servers prefer over GC-driven
+    # resizes.
     - name: MAX_MEMORY
       displayName: JVM max heap
       description: >-
-        Java heap ceiling (e.g. 2G, 3072M). Keep roughly 25% below the
-        container memory limit — the JVM needs headroom for non-heap
-        memory, and exceeding the limit gets the server OOM-killed.
+        Java heap ceiling (-Xmx, e.g. 2G, 3072M). Leave empty to size it
+        automatically to 75% of the container memory limit — it then
+        tracks the limit whenever you resize the server. If you set it
+        yourself, keep roughly 25% below the limit: the JVM needs
+        headroom for non-heap memory, and exceeding the limit gets the
+        server OOM-killed.
       type: string
-      default: "2G"
+      autoFromMemoryLimit:
+        percent: 75
 
     - name: INIT_MEMORY
       displayName: JVM initial heap
-      description: Starting heap size (-Xms). At most JVM max heap.
+      description: >-
+        Starting heap size (-Xms), at most JVM max heap. Leave empty to
+        match the automatic max heap (a fixed heap avoids GC resizes).
       type: string
-      default: "1G"
+      autoFromMemoryLimit:
+        percent: 75