n8n: its own image built from source, placed data, and what its workflows use

The module named /var/lib/n8n, /services/n8n/n8n-data and n8n.novox.be -
paths and a domain no definition may carry (ADR 0112). State and data are
placed directories; the public name is ${bound:route:name} (depends on
mesh-controller #149), for N8N_HOST and WEBHOOK_URL alike.

The endpoint said 5682 while the container publishes 5678. 5682 was one
machine's host port; the endpoint is the software's port and the mesh
assigns the machine's (ADR 0038).

n8n had been run from an image in a registry that no longer exists: the
upstream image plus shadow, a `media` group (2000) with `node` in it, and
a global `uuid`. That recipe is now this module's Dockerfile, built on the
upstream 1.71.3 image named in build.on by digest, with uuid pinned to the
version the running image carries (14.0.1) - Code nodes require() it. The
media group is how the container writes into the shared media library, a
read-write `access` (ADR 0051), mounted where workflows expect it,
/media-library.

The workflows also use a redis (the Redis nodes of the chat workflows) and a
Selenium Chrome (the scraper), which the previous deployment ran beside n8n.
Both are containers on the module's own network, publishing nothing, pinned
to the digests in use; redis keeps its append-only file in a placed
directory.

The basic-auth secret is gone: N8N_BASIC_AUTH_* was removed in n8n 1.0 and
did nothing. The grant's password is a 0400 file owned by `node`, read
through DB_POSTGRESDB_PASSWORD_FILE, so nothing secret is in the
environment. The credentials' encryption key is n8n's own, in the data
directory (config), and moves with it - nothing to mint or accept.

Verified: catalogue tests with MESH_CATALOGUE set; the Dockerfile built
against the pinned base gives n8n 1.71.3, uid 1000 in group 2000, uuid
14.0.1 - the running image's shape. Throwaway containers: an instance on
PostgreSQL 15 with an owner, a workflow and an encrypted credential;
stopped, copied, dumped from the copy, restored (--no-owner --role, the
uuid-ossp extension pre-made by the superuser) into a grant-shaped
database on the postgres module's pgvector image (PG17); the new shape
(password from the file, data dir copied) serves /healthz, the owner logs
in, the workflow is listed, and the credential decrypts with the carried
key. The node user writes into a root:2000 0775 library through the media
group; redis and Selenium resolve by name on the module network and
Selenium reports ready. Test containers and data removed.

modules/n8n/Dockerfile

@@ -0,0 +1,20 @@
+# n8n with what its workflows reach for beyond the upstream image.
+#
+# The base is named, not pinned here (novox/hq issue 044): module.json's `build.on` declares N8N_BASE
+# as the upstream image by digest, and the mesh hands the build its own copy (ADR 0097).
+ARG N8N_BASE
+FROM ${N8N_BASE}
+
+USER root
+# - `media` (GID 2000), with `node` in it: the shared media library is group-writable by the
+#   operator's media group, and a workflow files downloads into it. A container resource cannot add
+#   a supplementary group, so the image's own /etc/group carries it. 2000 is the operator's media
+#   group today; novox/hq 153 proposes reading it from the accessed data (${access:<id>:gid}).
+# - uuid, pinned to the version the workflows were written against: Code nodes require() it
+#   (NODE_FUNCTION_ALLOW_EXTERNAL=*), and a Code node can only require what is installed.
+RUN apk add --no-cache shadow \
+ && groupadd -g 2000 media \
+ && usermod -aG media node \
+ && npm install -g uuid@14.0.1
+
+USER node

modules/n8n/module.json

@@ -18,44 +18,60 @@
     }
   },
   "binds": {
-    "postgres-database": "/var/lib/n8n/database.json",
+    "postgres-database": "${dir:state}/database.json",
-    "route": "/var/lib/n8n/route.json"
+    "route": "${dir:state}/route.json"
   },
   "secrets": {
-    "postgres-database": "/var/lib/n8n/database.secret"
+    "postgres-database": "${dir:state}/database.secret"
-  },
-  "own-secrets": {
-    "basic-auth": "/var/lib/n8n/basic-auth.secret"
   },
+  "accesses": [
+    {
+      "path": "/services/media",
+      "mode": "read-write"
+    }
+  ],
   "listens": [
     {
       "name": "web",
-      "port": 5682,
+      "port": 5678,
       "protocol": "tcp",
       "from": "mesh",
-      "why": "the n8n editor and webhook endpoints over http; its public name is a route grant, and route-proxy reaches it on this published port"
+      "why": "the n8n editor, its REST API and the webhook endpoints workflows are triggered through; a public name is the route's"
     }
   ],
   "resources": [
     {
       "id": "state",
       "type": "directory",
-      "path": "/var/lib/n8n",
+      "mode": "0700",
-      "mode": "0700"
+      "place": "."
     },
     {
       "id": "data",
       "type": "directory",
-      "path": "/services/n8n/n8n-data",
       "mode": "0700",
       "owner": "1000:1000"
     },
+    {
+      "id": "cache",
+      "type": "directory",
+      "mode": "0700",
+      "owner": "999:999"
+    },
+    {
+      "id": "database-secret",
+      "type": "file",
+      "path": "${dir:state}/n8n-database.secret",
+      "mode": "0400",
+      "owner": "1000:1000",
+      "content": "${secret:postgres-database}"
+    },
     {
       "id": "server-env",
       "type": "file",
-      "path": "/var/lib/n8n/server.env",
+      "path": "${dir:state}/server.env",
       "mode": "0600",
-      "content": "N8N_HOST=${bound:route:name}\nN8N_PORT=5678\nN8N_PROTOCOL=https\nWEBHOOK_URL=https://${bound:route:name}/\nN8N_BASIC_AUTH_ACTIVE=true\nN8N_BASIC_AUTH_USER=admin\nN8N_BASIC_AUTH_PASSWORD=${secret:basic-auth}\nNODE_FUNCTION_ALLOW_BUILTIN=*\nNODE_FUNCTION_ALLOW_EXTERNAL=*\nDB_TYPE=postgresdb\nDB_POSTGRESDB_HOST=${bound:postgres-database:at}\nDB_POSTGRESDB_PORT=${bound:postgres-database:port}\nDB_POSTGRESDB_DATABASE=${bound:postgres-database:as}\nDB_POSTGRESDB_USER=${bound:postgres-database:as}\nDB_POSTGRESDB_PASSWORD=${secret:postgres-database}\n"
+      "content": "N8N_HOST=${bound:route:name}\nN8N_PORT=5678\nN8N_PROTOCOL=https\nWEBHOOK_URL=https://${bound:route:name}/\nNODE_FUNCTION_ALLOW_BUILTIN=*\nNODE_FUNCTION_ALLOW_EXTERNAL=*\nDB_TYPE=postgresdb\nDB_POSTGRESDB_HOST=${bound:postgres-database:at}\nDB_POSTGRESDB_PORT=${bound:postgres-database:port}\nDB_POSTGRESDB_DATABASE=${bound:postgres-database:as}\nDB_POSTGRESDB_USER=${bound:postgres-database:as}\nDB_POSTGRESDB_PASSWORD_FILE=/run/secrets/database\n"
     },
     {
       "id": "net",
@@ -66,18 +82,61 @@
       "id": "server",
       "type": "container",
       "name": "n8n",
-      "image": "n8nio/n8n@sha256:4846eb2f4b874ab04cde7fc1e249d2ddaec66e9aea64439beb2972cfea88e3c0",
+      "artifact": "server",
       "network": "n8n",
       "env-file": [
-        "/var/lib/n8n/server.env"
+        "${dir:state}/server.env"
       ],
       "ports": [
         "5678"
       ],
       "volumes": [
-        "/services/n8n/n8n-data:/home/node/.n8n"
+        "${dir:data}:/home/node/.n8n",
+        "${dir:state}/n8n-database.secret:/run/secrets/database:ro",
+        "/services/media:/media-library"
+      ]
+    },
+    {
+      "id": "cache-server",
+      "type": "container",
+      "name": "n8n-redis",
+      "image": "redis@sha256:8a1efc5f479551822b47424ccae982026b633f28818eab0387348120a61e10e2",
+      "network": "n8n",
+      "args": [
+        "redis-server",
+        "--appendonly",
+        "yes"
       ],
-      "secrets-in-environment": "n8n's loader honours <VAR>_FILE for every setting; convertible, awaiting a bed that proves it (N8N_BASIC_AUTH_* was removed in n8n 1.0 and is likely dead)"
+      "volumes": [
+        "${dir:cache}:/data"
+      ]
+    },
+    {
+      "id": "browser",
+      "type": "container",
+      "name": "n8n-selenium",
+      "image": "selenium/standalone-chrome@sha256:9ae1c78e9b2ca9fe4b22e57873b5ee34aeb8e814e3122293eef4c3abe4c5f448",
+      "network": "n8n",
+      "env": {
+        "SE_ENABLE_TRACING": "false",
+        "SE_NODE_MAX_SESSIONS": "5",
+        "SE_NODE_OVERRIDE_MAX_SESSIONS": "true"
+      }
     }
-  ]
+  ],
+  "build": {
+    "on": [
+      {
+        "arg": "N8N_BASE",
+        "image": "n8nio/n8n@sha256:4846eb2f4b874ab04cde7fc1e249d2ddaec66e9aea64439beb2972cfea88e3c0"
+      }
+    ],
+    "artifacts": [
+      {
+        "name": "server",
+        "kind": "image",
+        "from": "Dockerfile"
+      }
+    ]
+  }
 }