Hostfile-mDNS: Simple Multicast DNS Server with Hostfile

Simple mDNS server utilizing hostfile-like config file, syncing config between hierarchical mDNS nodes

Features

• mDNS-server
  • Run mDNS server with a simple, hostfile-like config file
• hostfile-sync
  • Build mDNS networks across multiple subnets with hostfile-sync function, syncing parent and children nodes
    • (Optional) Set HMDNS_PARENT_HOSTNAME container environment variable to the address of the sync parent. If not set, hostfile-sync function is disabled
    • Note: mDNS requests/responses from other mDNS server are not forwarded, only hostfiles of this server are synced
    • When a child Hostfile-mDNS cannot connect to the parent, hostfile of the child remains untouched until connected

Getting Started

• All commands below are for POSIX shell environments.
• Make sure the host local port 5353 (default, both TCP and UDP) is not in use.

Command-only method

• Deploy

  • podman

    # export HMDNS_PARENT_HOSTNAME=parent.address.to.sync   # uncomment to sync with parent
    
    podman run -d --network host -v hmdns-config:/config \
               --health-cmd "/healthcheck" --name "hmdns" \
               -e HMDNS_PARENT_HOSTNAME \
               docker.io/snoopy3476/hostfile-mdns:v1.0

  • docker

    # export HMDNS_PARENT_HOSTNAME=parent.address.to.sync   # uncomment to sync with parent
    
    docker run -d --network host -v hmdns-config:/config \
               --health-cmd "/healthcheck" --name "hmdns" \
               -e HMDNS_PARENT_HOSTNAME \
               docker.io/snoopy3476/hostfile-mdns:v1.0

• Configure

  • podman

    podman exec -it hmdns hostfile read   # print hostfile
    podman exec -it hmdns hostfile edit   # edit hostfile with vi command
    podman exec -it hmdns hostfile write   # write to hostfile from [stdin]
    
    # e.g.) replace inner hostfile with a new file 'new-list'
    # podman exec -i hmdns hostfile write < new-list

  • docker

    docker exec -it hmdns hostfile read   # print hostfile
    docker exec -it hmdns hostfile edit   # edit hostfile with vi command
    docker exec -it hmdns hostfile write   # write to hostfile from [stdin]
    
    # e.g.) replace inner hostfile with a new file 'new-list'
    # docker exec -i hmdns hostfile write < new-list

• C.f.)

  • It is also possible to bind-mounting /etc/hosts on the host directly, without managing the internal file hosts in the volume

    # podman
    podman run -d --network host -v /etc/hosts:/config/hosts \
        --health-cmd "/healthcheck" --name "hmdns" \
        docker.io/snoopy3476/hostfile-mdns:v1.0
    
    # docker
    docker run -d --network host -v /etc/hosts:/config/hosts \
        --health-cmd "/healthcheck" --name "hmdns" \
        docker.io/snoopy3476/hostfile-mdns:v1.0

With compose.yml file

• Deploy

  • podman

    # echo "HMDNS_PARENT_HOSTNAME=parent.address.to.sync" >> .env   # uncomment to sync with parent
    
    curl -fLO https://github.com/snoopy3476/Hostfile-mDNS/releases/download/v1.0/compose.yml \
      && podman-compose up -d

  • docker

    # echo "HMDNS_PARENT_HOSTNAME=parent.address.to.sync" >> .env   # uncomment to sync with parent
    
    curl -fLO https://github.com/snoopy3476/Hostfile-mDNS/releases/download/v1.0/compose.yml \
      && docker compose up -d

• Configure

  • podman

    podman-compose exec hmdns hostfile read   # print hostfile
    podman-compose exec hmdns hostfile edit   # edit hostfile with vi command
    podman-compose exec hmdns hostfile write   # write to hostfile from [stdin]
    
    # e.g.) replace inner hostfile with a new file 'new-list'
    # podman-compose exec -T hmdns hostfile write < new-list

  • docker

    docker compose exec hmdns hostfile read   # print hostfile
    docker compose exec hmdns hostfile edit   # edit hostfile with vi command
    docker compose exec hmdns hostfile write   # write to hostfile from [stdin]
    
    # e.g.) replace inner hostfile with a new file 'new-list'
    # docker compose exec -T hmdns hostfile write < new-list

• C.f.)

  • It is also possible to bind-mounting /etc/hosts on the host directly, without managing the internal file hosts in the volume

    # podman
    curl -fL https://github.com/snoopy3476/Hostfile-mDNS/releases/download/v1.0/compose-global-hostfile.yml -o compose.yml \
      && podman-compose up -d
    
    # docker
    curl -fL https://github.com/snoopy3476/Hostfile-mDNS/releases/download/v1.0/compose-global-hostfile.yml -o compose.yml \
      && docker compose up -d

Configuration

• Format of hostfile (hosts)

  • Line format: <target-ip> <domain-1.local> [domain-2.local] [domain-3.local] ...

    • Multiple lines to the same IP is allowed

    • Invalid lines are ignored on scan

    • Comments are ignored (string after '#' characters)

    • E.g.)

      # line format: <target-ip> <src-domain-1.local> [src-domain-2.local] ...
      #   e.g.) 192.168.1.1  mdns-domain.local another-domain.local third-domain.local
      192.168.1.1    mdns-domain.local another-domain.local third-domain.local
      
      192.168.1.2    mdns-domain2.local     # comment
      192.168.1.2    mdns-domain3.local     # same ip with different domain, on different line
      

  • When file changed, Hostfile-mDNS will reload it right after the save

• Configurable container environment variables

  • HMDNS_HOSTNAME: Hostname to bind
    (default: 0.0.0.0)
  • HMDNS_PORT: Port to bind (using TCP for syncing hostfile, and UDP for broadcasting mDNS)
    (default: 5353)
  • HMDNS_TTL: Time-to-Live of domains in seconds
    (default: 3600)
  • HMDNS_PARENT_HOSTNAME: Hostname of parent mDNS to sync hostfile.
    Current mDNS server syncs its hostfile with the one from the parent server HMDNS_PARENT_HOSTNAME: disabled if null
    (default: null)
  • HMDNS_PARENT_PORT: Port of parent mDNS to sync hostfile
    (default: 5353)
  • HMDNS_PARENT_SYNC_INTERVAL: Interval in seconds to sync hostfile with parent mDNS
    (default: 60)

Remarks

• Run this image with network mode host, as mDNS multicast packets are not broadcasted beyond its container subnet!