Running in Docker

Why Docker needs special handling on macOS and Windows

When dynamoip starts, it detects your machine's LAN IP to register DNS records and start the proxy. On a bare machine this works automatically — os.networkInterfaces() returns the real network interfaces.

Inside a Docker container the situation changes by platform:

Linux — Docker supports network_mode: host, which makes the container share the host's network stack. os.networkInterfaces() sees the real interfaces and auto-detection works with no extra config.

macOS and Windows — network_mode: host is not supported (Docker Desktop runs containers inside a Linux VM). The container only sees virtual interfaces (e.g. 172.17.0.2), not the host's actual LAN IP. Auto-detection returns the wrong address.

host.docker.internal does not solve this either — it resolves to the Docker Desktop VM's bridge IP (e.g. 192.168.65.2), not the LAN IP your router assigned to your machine.

The solution is to pass the LAN IP explicitly via the LAN_IP environment variable.

The LAN_IP environment variable

When LAN_IP is set, dynamoip uses it directly and skips auto-detection.

LAN_IP=192.168.1.42

docker-compose setup

Pass LAN_IP through using ${LAN_IP:-}. This means: use the value if set, otherwise pass nothing (so auto-detection runs on Linux where LAN_IP is left unset).

services:
  dynamoip:
    image: your-dynamoip-image
    network_mode: host          # Linux only — remove on macOS/Windows
    environment:
      LAN_IP: ${LAN_IP:-}
      CF_API_TOKEN: ${CF_API_TOKEN}
      CF_EMAIL: ${CF_EMAIL:-}
    volumes:
      - ./dynamoip.config.json:/app/dynamoip.config.json:ro
      - dynamoip-certs:/root/.localmap/certs

volumes:
  dynamoip-certs:

On macOS and Windows, remove network_mode: host — it is not supported and will cause an error.

Finding your LAN IP

macOS:

ipconfig getifaddr en0         # Wi-Fi
ipconfig getifaddr en1         # Ethernet

Or auto-detect from the default route:

route -n get default | awk '/interface:/{print $2}' | xargs ipconfig getifaddr

Linux:

ip route get 1 | awk '{print $7; exit}'

Windows (PowerShell):

(Get-NetRoute -DestinationPrefix '0.0.0.0/0' | Sort-Object RouteMetric |
    Select-Object -First 1 | Get-NetIPAddress -AddressFamily IPv4).IPAddress

Recommended: auto-detect with a startup script

Instead of manually setting LAN_IP every time, use a script that detects it and injects it before docker compose up.

macOS/Linux (start.sh):

#!/bin/bash
IFACE=$(route -n get default 2>/dev/null | awk '/interface:/{print $2}')
export LAN_IP=$(ipconfig getifaddr "$IFACE" 2>/dev/null)

# Linux fallback
if [ -z "$LAN_IP" ]; then
  export LAN_IP=$(ip route get 1 2>/dev/null | awk '{print $7; exit}')
fi

echo "LAN_IP=$LAN_IP"
docker compose up "$@"

Windows (start.ps1):

$env:LAN_IP = (Get-NetRoute -DestinationPrefix '0.0.0.0/0' |
    Sort-Object RouteMetric | Select-Object -First 1 |
    Get-NetIPAddress -AddressFamily IPv4).IPAddress

Write-Host "LAN_IP=$($env:LAN_IP)"
docker compose up

Run ./start.sh (or .\start.ps1) instead of docker compose up directly.

Linux: no extra config needed

On Linux, use network_mode: host and leave LAN_IP unset. dynamoip will auto-detect the LAN IP inside the container just as it does on a bare host.

services:
  dynamoip:
    network_mode: host
    environment:
      CF_API_TOKEN: ${CF_API_TOKEN}

Summary