reconnaissance is a small Erlang application for node discovery in a local network.
git clone git@github.com:wooga/reconnaissance.git
cd reconnaissance
./rebar com
reconnaissance comes preconfigured with a callback module that sends the host, port and node name:
When started twice with erl -pz ebin -s reconnaissance you can use reconnaissance:discover(). to find other nodes also having reconaissance running:
reconnaissance:discover().
[{{172,19,255,43},63616,<<"nonode@nohost">>}]
Here is the build-in callback module:
% Creates the payload that is sent as multicast packet
request() ->
<<"hello">>.
% Request is the payload from the request() function above
% The output is the response payload
response(_IP, _Port, Request) ->
list_to_binary(atom_to_list(node())).
% Called when the response from discoverd nodes is received
% Output will be stored in the node list
handle_response(IP, Port, Response) ->
{IP, Port, Response}.
The API calls are:
reconnaissance:discover/0meaning "find other nodes, wait half a second for responses and give me the list"reconnaissance:discover/1use a server name other thanreconnaissancereconnaissance:discover/2also specify the time to wait in ms.
Et voilá: reconnaissance!
Use in the environment:
{reconnaissance, [
{port, 31337},
{callback_module, reconnaissance_example_callback}
]}
Make sure multicast is routed propery by the OS:
sudo route add 224.0.0.1 10.8.0.3