flungo-docker/avahi

Docker image for the Avahi mDNS/DNS-SD daemon.

Avahi Docker Image

Docker image for the Avahi mDNS/DNS-SD daemon. Built on Alpine Linux to make the image as small as possible. Highly configurable through environment variables to support most usecases which need an Avahi Daemon.

Usage

Basic usage consists of running the docker container with the appropriate environment variables and volumes to achieve your desired behaviour.

docker run flungo/avahi

Environment variables

Environment variables are made available for all of the options of avahi-daemon.conf. The variable names are in the format <SECTION>_<OPTION> where <SECTION> is the capitalised section name from the configuration file and <OPTION> is the capitalised option name with - replaced by _. The table below outlines the available options:

Section	Option	Variable
server	host-name	SERVER_HOST_NAME
server	domain-name	SERVER_DOMAIN_NAME
server	browse-domains	SERVER_BROWSE_DOMAINS
server	use-ipv4	SERVER_USE_IPV4
server	use-ipv6	SERVER_USE_IPV6
server	allow-interfaces	SERVER_ALLOW_INTERFACES
server	deny-interfaces	SERVER_DENY_INTERFACES
server	check-response-ttl	SERVER_CHECK_RESPONSE_TTL
server	use-iff-running	SERVER_USE_IFF_RUNNING
server	enable-dbus	SERVER_ENABLE_DBUS
server	disallow-other-stacks	SERVER_DISALLOW_OTHER_STACKS
server	allow-point-to-point	SERVER_ALLOW_POINT_TO_POINT
server	cache-entries-max	SERVER_CACHE_ENTRIES_MAX
server	clients-max	SERVER_CLIENTS_MAX
server	objects-per-client-max	SERVER_OBJECTS_PER_CLIENT_MAX
server	entries-per-entry-group-max	SERVER_ENTRIES_PER_ENTRY_GROUP_MAX
server	ratelimit-interval-usec	SERVER_RATELIMIT_INTERVAL_USEC
server	ratelimit-burst	SERVER_RATELIMIT_BURST
wide-area	enable-wide-area	WIDE_AREA_ENABLE_WIDE_AREA
publish	disable-publishing	PUBLISH_DISABLE_PUBLISHING
publish	disable-user-service-publishing	PUBLISH_DISABLE_USER_SERVICE_PUBLISHING
publish	add-service-cookie	PUBLISH_ADD_SERVICE_COOKIE
publish	publish-addresses	PUBLISH_PUBLISH_ADDRESSES
publish	publish-hinfo	PUBLISH_PUBLISH_HINFO
publish	publish-workstation	PUBLISH_PUBLISH_WORKSTATION
publish	publish-domain	PUBLISH_PUBLISH_DOMAIN
publish	publish-dns-servers	PUBLISH_PUBLISH_DNS_SERVERS
publish	publish-resolv-conf-dns-servers	PUBLISH_PUBLISH_RESOLV_CONF_DNS_SERVERS
publish	publish-aaaa-on-ipv4	PUBLISH_PUBLISH_AAAA_ON_IPV4
publish	publish-a-on-ipv6	PUBLISH_PUBLISH_A_ON_IPV6
reflector	enable-reflector	REFLECTOR_ENABLE_REFLECTOR
reflector	reflect-ipv	REFLECTOR_REFLECT_IPV
reflector	reflect-filters	REFLECTOR_REFLECT_FILTERS
rlimits	rlimit-as	RLIMITS_RLIMIT_AS
rlimits	rlimit-core	RLIMITS_RLIMIT_CORE
rlimits	rlimit-data	RLIMITS_RLIMIT_DATA
rlimits	rlimit-fsize	RLIMITS_RLIMIT_FSIZE
rlimits	rlimit-nofile	RLIMITS_RLIMIT_NOFILE
rlimits	rlimit-stack	RLIMITS_RLIMIT_STACK
rlimits	rlimit-nproc	RLIMITS_RLIMIT_NPROC

If you find an option you require is missing, report this or make a PR adding that feature.

Examples

This sections contains several example usages for the. If you use this container for a common scenrio or if any of the examples can be improved, please let me know the configurtion you have used so that I can add it here or submit a PR adding it as an example.

Reflect mDNS broadcasts between networks

To reflect mDNS broadcasts between two docker networks (net1 and net2 in the example given) the reflector should be enabled by setting REFLECTOR_ENABLE_REFLECTOR=yes.

# Create a container named mdns-reflector attached to net1
docker run -d --name=mdns-reflector \
  --network net1 \
  -e REFLECTOR_ENABLE_REFLECTOR=yes \
  flungo/avahi
# Attach the container to the net2 network
docker network connect net2 mdns-reflector

See Connecting to a phyiscal network to see how you can connect the container to a physical network - for example if you wanted to reflect mDNS between two WiFi VLANs).

Connecting to a physical network

It is common to want to use this container with one or more physical networks (e.g. as a reflector between WiFi network), in order to do this a docker network can be created using the macvlan driver. The following example creates a macvlan network named physical connected to the eno1 interface with subnet 10.0.0.0/24 and gateway 10.0.0.1.

docker network create --driver macvlan --subnet 10.0.0.0/24 --gateway 10.0.0.1 --opt parent=eno1 physical

You can also connect to a VLAN on a physical interface by suffixing the parent with . and the VLAN ID (e.g. --opt parent=eno1.123 for VLAN 123 on the eno1 interface. The sub-interface does not need to exist before running the command to create the network as the driver will automatically create this.

To ensure that an IP conflict does not occur, you should specify an available IP address on your physical network when attaching the network to your container. Assuming that your container is called avahi and 10.0.0.10 is an available IP in that network, you can connect this network as follows:

docker network connect physical avahi --ip 10.0.0.10

avahi's Issues

this sucks...

I don't get how you could settle for this being an option for anything

Does it really work?

Sorry for asking, maybe I just don't understand your code:

After adding "avahi-tools" to Dockerfile and sh'ing into the running container I do:
avahi-browse --all --resolve
which yields:
Failed to create client object: Daemon not running

Also with SERVER_ENABLE_DBUS=yes avahi-daemon cannot start.

Which means that I cannot publish any service to avahi-daemon (from other containers).

Ideas / suggestions? Thanks!

avahi to reflect mDNS between docker internal LAN and outside real-world networking

Hi, love the idea of your container (so thank you!)- i thought you solved my problem. You probably still can but im stumbling on the setup to the outside world.

Your README.md spells out how to connect avahi container between two internal docker networks (net1 to net2 in your example)..... but I need to go from an internal docker LAN (named 'kTier2_PROXYtoAPP' in my case - which is 172.20.2.0/24) to the outside world (in my case, the NIC of the ubuntu host, on 10.1.3.0/24), which is where the mDNS announce packets are coming from.

after booting your container (attaching to --network kTier2_PROXYtoAPP), I tried 'docker network connect' to

• 'host' (wasn't allowed) and
• 'bridge' (allowed, but connected me to docker0 LAN - 172.12.0.0/24 - which is unused for me)
  but neither worked.

any ideas? Im a bit of a noob to docker networking (im a real world networking expert though if that helps!).
thanks,
Keiran.

ARM Containers

Hello,

Any chance there's going to be an arm compatible image?

Thanks.

Avahi PID file not removed on unclean shutdown of container/Daemon already running on PID 1

Hi there. Thanks for making this.

If the container shuts down uncleanly, a PID file is left in /var/run/avahi-daemon/pid

This file prevents avahi from starting, and the container restarts indefinitely.

I've observed this happens when my server reboots (which I've raised the shutdown timeout to 120s to help mitigation), and when I kill the container.

I tried both of these lines in my docker-compose file which didn't help.
entrypoint: ["rm","-f","/var/run/avahi-daemon/pid"]
command: rm -f /var/run/avahi-daemon/pid

Would you be able to alter the entrypoint/startup scripts in the container to remove an existing pid file?

Feature request: remote networks

I'd love to be able to run this docker on separate systems connected to separate networks (that already have routing enabled) and allow the instances to talk to each other rather than having one docker with all the networks needed present.

Container healthcheck

Anyway, I could setup healthcheck for the container? Everyone few weeks the container stops functioning for unknown reason with not much info in the logs. It shows running and no signs of issues, however the mDNS fails to function. Only a restart of the container restores it.

I have a deunhealth container which monitors for unhealthy containers and if found then it automatically restarts them. The containers however need the healthcheck feature on for this.

Avahi dbus

Hii,
was just wondering if theres any way of enabling dbus internally? Making it run on container side and not host???? Im running rancher and i cant seem to find a way to run avahi dbus.