Merge pull request 'Adoption mode: guards, and a filter unit that never flushes the ruleset (hq ADR 0100, 0103)' (#38) from feat/adoption-mode into main

modules/lavinmq/module.json

@@ -53,6 +53,9 @@
       "why": "modules on any machine that were granted a queue"
     }
   ],
+  "guards": [
+    15672
+  ],
   "resources": [
     {
       "id": "mesh-state",

modules/nftables/client.ts

@@ -1,7 +1,8 @@
 // The firewall's own code, in the module (novox/hq ADR 0039). The mesh computes this node's whole
 // rule set from every module's `listens` and writes it to /etc/nftables.conf (novox/hq ADR 0045);
-// the module loads it (the nftables service, reloaded whenever the rules change). This code exists
+// the module loads it through its own mesh-filter unit, reloaded whenever the rules change, whose
-// only to read back what is actually enforced — the enforcement itself is declarative.
+// stop deletes only the mesh's table and never flushes the whole ruleset (novox/hq ADR 0100). This
+// code exists only to read back what is actually enforced — the enforcement itself is declarative.
 
 import { execFile } from "node:child_process";
 import { promisify } from "node:util";

modules/nftables/module.json

@@ -19,13 +19,31 @@
       "type": "package",
       "package": "nftables"
     },
+    {
+      "id": "unit",
+      "type": "file",
+      "path": "/etc/systemd/system/mesh-filter.service",
+      "content": "[Unit]\nDescription=The mesh's packet filter, derived from what is assigned to this node\nWants=network-pre.target\nBefore=network-pre.target\n\n[Service]\nType=oneshot\nRemainAfterExit=yes\nExecStart=nft -f /etc/nftables.conf\nExecReload=nft -f /etc/nftables.conf\nExecStop=nft delete table inet mesh\n\n[Install]\nWantedBy=multi-user.target\n",
+      "mode": "0644"
+    },
+    {
+      "id": "stock-unit-stop",
+      "type": "file",
+      "path": "/etc/systemd/system/nftables.service.d/mesh.conf",
+      "content": "# The mesh: stopping the stock unit deletes only the mesh's table, never the whole ruleset\n# (novox/hq ADR 0100) — a flush would take the container runtime's rules and any firewall with it.\n[Service]\nExecStop=\nExecStop=nft delete table inet mesh\n",
+      "mode": "0644"
+    },
     {
       "id": "load",
       "type": "service",
-      "unit": "nftables.service",
+      "unit": "mesh-filter.service",
       "state": "running",
       "boot": "enabled",
       "restart-on": [
+        "unit",
+        "stock-unit-stop"
+      ],
+      "reload-on": [
         "filtering"
       ]
     }

modules/postgres/module.json

@@ -32,6 +32,9 @@
       "why": "modules on any machine that were granted a database"
     }
   ],
+  "guards": [
+    5432
+  ],
   "serves": {
     "postgres-database": {
       "port": 5432