Docker PoC for batteries

eg4battery/docker-compose.yml

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+# eg4-battery — local Docker deployment.
+#
+# Usage:
+#   docker compose build     # one-time, after changes to Dockerfile / requirements / source
+#   docker compose up -d     # start daemon in background
+#   docker compose logs -f   # tail the daemon log
+#   docker compose down      # stop + remove
+#
+# This deployment runs side-by-side with the systemd `eg4-battery.service`.
+# Stop systemd before bringing this up, or each pack will be polled twice
+# per cycle (and HA will see duplicate publishes from two MQTT clients):
+#   sudo systemctl stop eg4-battery.service
+#
+# Side-by-side cutover, once verified:
+#   sudo systemctl disable --now eg4-battery.service
+
+services:
+  eg4-battery:
+    build: .
+    image: eg4-battery:local
+    container_name: eg4-battery
+    restart: unless-stopped
+
+    # USB-RS-485 adapters → daemon. The /dev/ttyUSBN device numbers can shift
+    # on USB reshuffles; the by-id symlinks (mounted via the volume below)
+    # are the stable identifiers the YAML config references.
+    devices:
+      - /dev/ttyUSB0:/dev/ttyUSB0
+      - /dev/ttyUSB1:/dev/ttyUSB1
+      - /dev/ttyUSB3:/dev/ttyUSB3
+
+    # Read-only bind: lets the container resolve /dev/serial/by-id/usb-FTDI_*
+    # symlinks (Docker doesn't propagate symlinks via `devices:`).
+    volumes:
+      - /dev/serial:/dev/serial:ro
+      - ${HOME}/.config/eg4-battery:/config:ro
+
+    # MQTT credentials override the YAML's mqtt: block when set. Comment out
+    # to use the values from eg4-battery.yaml.
+    environment:
+      - MQTT_HOST=10.0.0.41
+      - MQTT_USERNAME=mqtt
+      - MQTT_PASSWORD=nutterino
+
+    # Standard log driver — `docker logs` reads from stdout
+    logging:
+      driver: json-file
+      options:
+        max-size: "10m"
+        max-file: "3"