This is how to install portainer on the swarm you created using this gist note this should work on non-swarm installs too!
Download the portain stack yaml that will do this for you
curl -L https://downloads.portainer.io/ce2-17/portainer-agent-stack.yml -o portainer-agent-stack.yml
now run it
sudo docker stack deploy -c portainer-agent-stack.yml portainer
this will create a single portainer container that runs on the management node and deploy the agent to all worker nodes, once complete you can now access portainer at http://docker-host-ip:9000 and define your admin users etc
You now have a fully function docker swarm with portainer and can deploy containers, stacks or templates.
How to use portainer is beyond the scope of this gist
This is the portainer install doc at time of writing for reference but the instructions above will work just fine
One step forward two steps back. So I installed a BE portainer outside the 3-node swarm. It works, now the problem is that I'm stuck with the license limit of 3 nodes that I now surpassed. They are asking 150 dollars per year. What do you think ?
Potential workaround, install a standalone agent on one of the nodes. → doesn't work