Setting up a swarm
The first step for running a swarm is to have a number of hosts ready with Docker installed. It does not matter if you use the install script from get.docker.com or if you use Docker Machine. You also need to be sure that a few ports are open between the servers, as given here:
2377 TCP port for cluster management
7946 TCP and UDP port for node communication
4789 TCP and UDP port for overlay network
Take a moment to get or assign a static IP address to the hosts that will be the swarm managers. Each manager must have a static IP address so that workers know how to connect to them. Worker addresses can be dynamic but the IP of the manager must be static.
As you plan your swarm, take a moment to decide how many managers you are going to need. The minimum number to run and still maintain fault tolerance is three. For larger clusters, you may need as many as five or seven. Very rarely will you need more than that. In any case, the number of managers should be odd. Docker Swarm...
