Building a Docker Swarm

1. On all three servers, install Docker CE.

sudo apt-get update

sudo apt-get -y install 
   apt-transport-https 
   ca-certificates 
   curl 
   gnupg-agent 
   software-properties-common

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

sudo add-apt-repository 
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu 
   $(lsb_release -cs) 
   stable"

sudo apt-get update

sudo apt-get install -y docker-ce=5:18.09.5~3-0~ubuntu-bionic docker-ce-cli=5:18.09.5~3-0~ubuntu-bionic containerd.io

2. Add cloud_user to the Docker group so that you can run docker commands as cloud_user.

sudo usermod -a -G docker cloud_user

Log out each server, then log back in.

3. You can verify the installation on each server like so:

docker version

1. On the swarm manager server, initialize the swarm. Be sure to replace <swarm manager private IP> in this command with the actual Private IP of the swarm manager (NOT the public IP).

docker swarm init --advertise-addr <swarm manager private IP>

1. On the swarm manager, get a join command with a token:

docker swarm join-token worker

This should provide a command that begins docker swarm join .... Copy that command and run it on both worker servers.

NOTE: If you have any trouble, on the swarm manager try: docker swarm leave --force and then docker swarm init --advertise-addr [privater ip of the swarm manager] After that, run the provided command to join the workers to the swarm.

2. Go back to the swarm manager and list the nodes.

docker node ls

Verify that you can see all three servers listed (including the manager). All three should have a status of READY. Once all three servers are ready, you have built your own Docker swarm cluster!