Docker GNATSD Cluster example

Below is an example of how to setup gnatsd cluster using Docker.

I have put 3 different configurations (one per gnatsd server) under a folder named conf as follows:

tree conf

conf
|-- gnatsd-A.conf
|-- gnatsd-B.conf
`-- gnatsd-C.conf

Each one of those files have the following content below: (Here I am using ip 192.168.59.103 as an example, so just replace with the proper ip from your server)

Example: Setting up a cluster on 3 different servers provisioned beforehand

gnatsd-A

# Cluster Server A

port: 7222

cluster {
  host: '0.0.0.0'
  port: 7244

  routes = [
    nats-route://192.168.59.103:7246
    nats-route://192.168.59.103:7248
  ]
}

gnatsd-B

# Cluster Server B

port: 8222

cluster {
  host: '0.0.0.0'
  port: 7246

  routes = [
    nats-route://192.168.59.103:7244
    nats-route://192.168.59.103:7248
  ]
}

gnatsd-C

# Cluster Server C

port: 9222

cluster {
  host: '0.0.0.0'
  port: 7248

  routes = [
    nats-route://192.168.59.103:7244
    nats-route://192.168.59.103:7246
  ]
}

Starting the containers

Then on each one of your servers, you should be able to start the gnatsd image as follows:

docker run -it -p 0.0.0.0:7222:7222 -p 0.0.0.0:7244:7244 --rm -v $(pwd)/conf/gnatsd-A.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 7222 -D -V

docker run -it -p 0.0.0.0:8222:8222 -p 0.0.0.0:7246:7246 --rm -v $(pwd)/conf/gnatsd-B.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 8222 -D -V

docker run -it -p 0.0.0.0:9222:9222 -p 0.0.0.0:7248:7248 --rm -v $(pwd)/conf/gnatsd-C.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 9222 -D -V

Example: Setting a gnatsd cluster one by one

In this scenario:

We bring up A and get its ip (nats-route://192.168.59.103:7244)
Then create B and then use address of A in its configuration.
Get the address of B nats-route://192.168.59.104:7246 and create C and use the addresses of A and B.

First, we create the Node A and start up a gnatsd server with the following config:

# Cluster Server A

port: 4222

cluster {
  host: '0.0.0.0'
  port: 7244

}

docker run -it -p 0.0.0.0:4222:4222 -p 0.0.0.0:7244:7244 --rm -v $(pwd)/conf/gnatsd-A.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 4222 -D -V

Then we proceed to create the next node. We realize that the first node has ip:port as 192.168.59.103:7244 so we add this to the routes configuration as follows:

# Cluster Server B

port: 4222

cluster {
  host: '0.0.0.0'
  port: 7244

  routes = [
    nats-route://192.168.59.103:7244
  ]
}

Then start server B:

docker run -it -p 0.0.0.0:4222:4222 -p 0.0.0.0:7244:7244 --rm -v $(pwd)/conf/gnatsd-B.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 4222 -D -V

Finally, we create another Node C. We now know the routes of A and B so we can add it to its configuration:

# Cluster Server C

port: 4222

cluster {
  host: '0.0.0.0'
  port: 7244

  routes = [
    nats-route://192.168.59.103:7244
    nats-route://192.168.59.104:7244
  ]
}

Then start it:

docker run -it -p 0.0.0.0:4222:4222 -p 0.0.0.0:7244:7244 --rm -v $(pwd)/conf/gnatsd-C.conf:/tmp/cluster.conf apcera/gnatsd -c /tmp/cluster.conf -p 9222 -D -V

Now, the following should work: make a subscription to Node A then publish to Node C. You should be able to to receive the message without problems.

nats-sub -s "nats://192.168.59.103:7222" hello &

nats-pub -s "nats://192.168.59.105:7222" hello world

[#1] Received on [hello] : 'world'

# GNATSD on Node C logs:
[1] 2015/06/23 05:20:31.100032 [TRC] 192.168.59.103:7244 - rid:2 - <<- [MSG hello RSID:8:2 5]

# GNATSD on Node A logs:
[1] 2015/06/23 05:20:31.100600 [TRC] 10.0.2.2:51007 - cid:8 - <<- [MSG hello 2 5]

wallyqs/docker-gnatsd-cluster.org