Update the repositories
sudo apt-get update

Install prereqs
sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg-agent \
    software-properties-common

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

Check the fingerprint of the key
sudo apt-key fingerprint 0EBFCD88

Add the stable repository
sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"
   
Install Docker and Docker Compose
sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose

Check installed version
sudo docker version

Create Docker Swarm
From the first node (AKA: Manager node) run the following command:

docker swarm init --advertise-addr <MANAGER-IP>

docker swarm join --token <LONG-TOKEN-ID> <IP-ADDRESS-OF-MANAGER:PORT>

Install Portainer
mkdir -p /opt/portainer && cd /opt/portainer
curl -L https://downloads.portainer.io/portainer-agent-stack.yml -o portainer-agent-stack.yml


docker stack deploy --compose-file=portainer-agent-stack.yml portainer