Demonstrates how to build a simple service that will be discovered via a Python script using zeroconf.

The service is a very simple API that responds with a tiny block of JSON. It's configured to run with the name simpleapi (defined in simpleapi.service).

The main client will query the network for any services and discover implementations of the service (based on it's name). Based on the discovered services it will make a request to each to obtain the simple JSON block.

Start the docker image(s):

sudo docker run --net=host -it --rm antillionos/zeroconf-example-service

Install the required Python dependencies:

pip install -r client/requirements.txt

Discover the available services using the following command (you may receive a firewall notification as it will also be listening on the socket):

python client/find_and_call.py

Assuming all goes well, you should see something like the following:

Waiting 10s for services to become available (Ctrl+C to cancel search early)

Service developmentbox simpleapi._http._tcp.local. of type _http._tcp.local. state changed: ServiceStateChange.Added
Discovered a service: {u'path': '/api/v1', u'port': 8000, u'address': '11.0.0.11'}

Querying 1 services found
Service @ 11.0.0.11 responded with 200:{"Hello": "World!"} 

If you see:

Mar  7 14:44:20 b0b7383106e2 avahi-daemon[70]: sendmsg() to 0:0:ff02:: failed: Invalid argument

Avahi is failing to broadcast to mDNS; make sure you started the container with --net=host.

If you can't see your service come up, try client/browser.py which will show all services it can find.

Pass the --debug flag if you wish to see the mDNS network traffic; be warned: it's noisy.

The service Dockerfile is based, in part, on the work from https://github.com/mhaberler/docker-avahi which solves common dbus problems.