warn when a host's kernel has cgroup memory accounting disabled

src/lib/openapi.generated.json

@@ -12505,6 +12505,9 @@
                         },
                         "name": {
                           "type": "string"
+                        },
+                        "memoryLimitSupported": {
+                          "type": "boolean"
                         }
                       }
                     },
@@ -12523,7 +12526,8 @@
                     "serverVersion": "string",
                     "containers": 0,
                     "images": 0,
-                    "name": "string"
+                    "name": "string",
+                    "memoryLimitSupported": true
                   },
                   "hawser": {}
                 }

src/lib/utils/memory-support.ts

@@ -0,0 +1,30 @@
+/**
+ * Whether the daemon's kernel supports per-container memory accounting, read from
+ * Docker `/info`. When the cgroup memory controller is disabled in the kernel boot
+ * config (common on Raspberry Pi and some ARM boards), the daemon reports
+ * `MemoryLimit: false` and every container's memory usage shows as 0. Docker itself
+ * detects this - we surface it so the user isn't left guessing why memory is blank.
+ */
+
+export interface MemorySupportInfo {
+	/** true = the UI can show a warning that memory accounting is off. */
+	warn: boolean;
+	/** Docker's own `/info.MemoryLimit`. */
+	memoryLimitSupported: boolean;
+	/** Docker's own `/info.SwapLimit`. */
+	swapLimitSupported: boolean;
+}
+
+/**
+ * Derive the memory-support flags from a Docker `/info` response. `MemoryLimit`/
+ * `SwapLimit` are booleans; a missing/undefined field is treated as SUPPORTED (no
+ * warning) so an older daemon or a partial info payload never produces a false alarm.
+ */
+export function memorySupportFromInfo(info: { MemoryLimit?: boolean; SwapLimit?: boolean } | null | undefined): MemorySupportInfo {
+	const memoryLimitSupported = info?.MemoryLimit !== false;
+	const swapLimitSupported = info?.SwapLimit !== false;
+	return { warn: !memoryLimitSupported, memoryLimitSupported, swapLimitSupported };
+}
+
+/** Link to the manual section explaining how to enable cgroup memory accounting. */
+export const MEMORY_SUPPORT_DOC_URL = 'https://dockhand.pro/manual/#troubleshooting-rpi-memory';