Elixir

Connecting nodes on different machines

Jun 18, 2016

Let’s see how we can connect multiple nodes on the same machine:

$ iex --sname foo
iex(foo@yosriady)> Node.list
[]
$ iex --sname bar
iex(bar@yosriady)> Node.list
[]

We have two nodes, both unaware of each other. Let’s connect them:

iex(foo@yosriady)> Node.ping :"bar@yosriady"
:pong # returns :pang if ping failed
iex(foo@yosriady)> Node.list
[:"bar@yosriady"]
iex(bar@yosriady)> Node.list
[:"foo@yosriady"]

Both nodes are now aware of each other!

Now let’s see how we can connect multiple nodes on different machines over the network. You’ll need to get the two machines’ IP addresses via ifconfig:

$ ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
	options=3<RXCSUM,TXCSUM>
	inet6 ::1 prefixlen 128
	inet 127.0.0.1 netmask 0xff000000
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
	nd6 options=1<PERFORMNUD>
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	ether 34:36:3b:d4:fc:dc
	inet6 fe80::3636:3bff:fed4:fcdc%en0 prefixlen 64 scopeid 0x4
	inet 10.238.82.82 netmask 0xfffffe00 broadcast 10.238.83.255
	nd6 options=1<PERFORMNUD>
	media: autoselect
	status: active

From the above, my IP address is 10.238.82.82. My other machine has IP 10.238.82.85:

$ iex --name foo@10.238.82.82 --cookie chocolate
iex(foo@10.238.82.82)> Node.ping :"bar@10.238.82.85"
:pong
iex(foo@10.238.82.82)> Node.list
[:"bar@10.238.82.85"]
$ iex --name bar@10.238.82.85 --cookie chocolate
iex(bar@10.238.82.85)> Node.list
[:"foo@10.238.82.82"]