docker-home-server/docker-compose/watchtower/docker-compose.yml

version: "3"
services:
  watchtower:
  # replace containrrr/watchtower with nicholas-fedor/watchtower
    image: nickfedor/watchtower
    container_name: watchtower
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/localtime:/etc/localtime:ro
    environment:
      WATCHTOWER_SCHEDULE: 0 0 1 * * *
      #TZ: America/New_York
      WATCHTOWER_CLEANUP: "true"
      WATCHTOWER_DEBUG: "true"
      WATCHTOWER_NOTIFICATION_REPORT: "true"
      WATCHTOWER_NOTIFICATION_URL: >
        discord://YourDiscordToken@YourDiscordID,generic://discord.com/api/webhooks/YourDiscordID/YourDiscordToken
#        slack://yourworkspace@YourSlackToken@YourChannelID
      WATCHTOWER_NOTIFICATION_TEMPLATE: |
        {{- if .Report -}}
          {{- with .Report -}}
        {{len .Scanned}} Scanned, {{len .Updated}} Updated, {{len .Failed}} Failed
              {{- range .Updated}}
        - {{.Name}} ({{.ImageName}}): {{.CurrentImageID.ShortID}} updated to {{.LatestImageID.ShortID}}
              {{- end -}}
              {{- range .Fresh}}
        - {{.Name}} ({{.ImageName}}): {{.State}}
            {{- end -}}
            {{- range .Skipped}}
        - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}}
            {{- end -}}
            {{- range .Failed}}
        - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}}
            {{- end -}}
          {{- end -}}
        {{- else -}}
          {{range .Entries -}}{{.Message}}{{"\n"}}{{- end -}}
        {{- end -}}
    restart: always
    stdin_open: true    # to attach to containers
    tty: true           # also used to attach to containers
#    network_mode: service:wireguard     # To run through vpn service container, in turn UI port must be forwarded inside vpn. No local access unless otherwise defined
    networks:           # Specify network for container
      - homelab
networks:    # I don't know why but you have to specify the network 2x. In service, and in this tag area..
  homelab:
    external: true      # This option causes compose to join the above network instead of making a _default one (supposedly)