Watchtower Docker on Synology NAS — Full Setup Guide

Why Run Watchtower on Synology?

Synology NAS devices running DSM 7.x with Container Manager are popular homelab Docker hosts for services like Plex, Nextcloud, Home Assistant, Vaultwarden, and Portainer. Without watchtower docker synology setup, every image update for these self-hosted services requires SSH sessions and manual docker pull + restart commands.

Installing docker watchtower synology automates all of this — your Synology apps stay current with zero maintenance overhead.

Prerequisites

• Synology NAS with DSM 7.x
• Container Manager (formerly Docker package) installed from Package Center
• SSH enabled on the NAS (Control Panel → Terminal & SNMP)
• Admin or docker-group access

Method 1: Install via SSH (Recommended)

SSH into your Synology and run the standard Docker install command:

# SSH into Synology
ssh admin@192.168.1.x

# Install watchtower docker synology
sudo docker run -d \
  --name watchtower \
  --restart unless-stopped \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e WATCHTOWER_CLEANUP=true \
  -e WATCHTOWER_POLL_INTERVAL=21600 \
  containrrr/watchtower

Method 2: Docker Compose via SSH

Create a compose file on the NAS:

# Create directory for watchtower config
mkdir -p /volume1/docker/watchtower
cd /volume1/docker/watchtower

# Create docker-compose.yml
cat > docker-compose.yml <<'EOF'
version: "3.8"
services:
  watchtower:
    image: containrrr/watchtower
    container_name: watchtower
    restart: unless-stopped
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/localtime:/etc/localtime:ro
    environment:
      - WATCHTOWER_CLEANUP=true
      - WATCHTOWER_POLL_INTERVAL=21600
      - WATCHTOWER_SCHEDULE=0 0 4 * * *
EOF

# Start watchtower
sudo docker compose up -d

Method 3: Container Manager GUI

Using the Synology Container Manager web interface:

1. Open Container Manager from the Synology desktop
2. Go to Registry and search for containrrr/watchtower
3. Download the latest image
4. Go to Container → Create
5. Select the watchtower image
6. Under Volume, add a bind mount: Host path /var/run/docker.sock → Mount path /var/run/docker.sock
7. Under Environment, add: WATCHTOWER_CLEANUP=true, WATCHTOWER_POLL_INTERVAL=21600
8. Enable Auto Restart
9. Click Done

Common Synology Watchtower Issues

Issue: "Permission denied: /var/run/docker.sock"

# Add your user to the docker group
sudo synogroup --add docker $USER
# OR run with sudo explicitly

Issue: Container Manager shows "Unhealthy" after install

Watchtower doesn't have a built-in Docker health check endpoint — "Unhealthy" in Container Manager's UI is cosmetic. Check sudo docker logs watchtower to confirm it's actually running and checking containers.

Issue: Watchtower updates Synology packages unexpectedly

Use the label-exclude method to protect containers you don't want auto-updated:

# Add to any sensitive container
labels:
  - "com.centurylinklabs.watchtower.enable=false"

Recommended Synology Configuration

services:
  watchtower:
    image: containrrr/watchtower
    container_name: watchtower
    restart: unless-stopped
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/localtime:/etc/localtime:ro
    environment:
      - WATCHTOWER_CLEANUP=true
      - WATCHTOWER_SCHEDULE=0 0 3 * * *    # 3 AM daily
      - WATCHTOWER_NOTIFICATIONS=slack
      - WATCHTOWER_NOTIFICATION_SLACK_HOOK_URL=https://hooks.slack.com/...