examples: Update paperless-ngx to use PostgreSQL (#153)

Match the real-world setup with Redis + PostgreSQL + App.
Remove NFS + PostgreSQL warning since it works fine in practice.

examples/README.md

@@ -9,7 +9,7 @@ Real-world examples demonstrating compose-farm patterns for multi-host Docker de
 | [traefik](traefik/) | Infrastructure | Reverse proxy, Let's Encrypt, file-provider |
 | [mealie](mealie/) | Single container | Traefik labels, resource limits, environment vars |
 | [uptime-kuma](uptime-kuma/) | Single container | Docker socket, user mapping, custom DNS |
-| [paperless-ngx](paperless-ngx/) | Multi-container | Redis + App stack (SQLite) |
+| [paperless-ngx](paperless-ngx/) | Multi-container | Redis + PostgreSQL + App stack |
 | [autokuma](autokuma/) | Multi-host | Demonstrates `all` keyword (runs on every host) |
 
 ## Key Patterns
@@ -96,15 +96,14 @@ Database-backed apps with multiple services:
 services:
   redis:
     image: redis:7
+  db:
+    image: postgres:16
   app:
     depends_on:
       - redis
+      - db
 ```
 
-> **NFS + PostgreSQL Warning:** PostgreSQL should NOT run on NFS storage due to
-> fsync and file locking issues. Use SQLite (safe for single-writer on NFS) or
-> keep PostgreSQL data on local volumes (non-migratable).
-
 ### AutoKuma Labels (Optional)
 
 The autokuma example demonstrates compose-farm's **multi-host feature** - running the same stack on all hosts using the `all` keyword. AutoKuma itself is not part of compose-farm; it's just a good example because it needs to run on every host to monitor local Docker containers.

examples/paperless-ngx/.env

@@ -1,3 +1,4 @@
 # Copy to .env and fill in your values
 DOMAIN=example.com
-PAPERLESS_SECRET_KEY=change-me-to-a-random-string
+POSTGRES_PASSWORD=change-me-to-a-secure-password
+PAPERLESS_SECRET_KEY=change-me-to-a-long-random-string

examples/paperless-ngx/compose.yaml

@@ -1,44 +1,57 @@
 # Paperless-ngx - Document management system
 #
 # Demonstrates:
-# - HTTPS route: paperless.${DOMAIN} (e.g., paperless.example.com) with Let's Encrypt
-# - HTTP route: paperless.local for LAN access without TLS
-# - Multi-container stack (Redis + App with SQLite)
-#
-# NOTE: This example uses SQLite (the default) instead of PostgreSQL.
-# PostgreSQL should NOT be used with NFS storage due to fsync/locking issues.
-# If you need PostgreSQL, use local volumes for the database.
+# - HTTPS route: paperless.${DOMAIN} with Let's Encrypt
+# - HTTP route: paperless.local for LAN access
+# - Multi-container stack (Redis + PostgreSQL + App)
+# - Separate env_file for app-specific settings
 name: paperless-ngx
 services:
-  redis:
-    image: redis:8
+  broker:
+    image: redis:7
     container_name: paperless-redis
     restart: unless-stopped
     networks:
       - mynetwork
     volumes:
-      - /mnt/data/paperless/redis:/data
+      - /mnt/data/paperless/redisdata:/data
+
+  db:
+    image: postgres:16
+    container_name: paperless-db
+    restart: unless-stopped
+    networks:
+      - mynetwork
+    volumes:
+      - /mnt/data/paperless/pgdata:/var/lib/postgresql/data
+    environment:
+      POSTGRES_DB: paperless
+      POSTGRES_USER: paperless
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
 
   paperless:
     image: ghcr.io/paperless-ngx/paperless-ngx:latest
     container_name: paperless
     restart: unless-stopped
     depends_on:
-      - redis
+      - db
+      - broker
     networks:
       - mynetwork
     ports:
       - "8000:8000"
     volumes:
-      # SQLite database stored here (safe on NFS for single-writer)
       - /mnt/data/paperless/data:/usr/src/paperless/data
       - /mnt/data/paperless/media:/usr/src/paperless/media
       - /mnt/data/paperless/export:/usr/src/paperless/export
       - /mnt/data/paperless/consume:/usr/src/paperless/consume
     environment:
-      PAPERLESS_REDIS: redis://redis:6379
+      PAPERLESS_REDIS: redis://broker:6379
+      PAPERLESS_DBHOST: db
       PAPERLESS_URL: https://paperless.${DOMAIN}
       PAPERLESS_SECRET_KEY: ${PAPERLESS_SECRET_KEY}
+      PAPERLESS_TIME_ZONE: America/Los_Angeles
+      PAPERLESS_OCR_LANGUAGE: eng
       USERMAP_UID: 1000
       USERMAP_GID: 1000
     labels: