I defined Docker Swarm cluster with 20 nodes and created service using Nginx HTTP server Docker image. I scaled it to 1000 container instances, which took a while on my demo hardware. Containers are up and running but to get such statistics from Portainer CE UI is quite difficult, so I suggest using CLI in such a case:

docker service ps nginx3 | grep Running | wc -l

I got exacly 1000 containers on my service named “nginx3”.

Hardware is not so much utilized, combined 2 servers RAM usage oscillates around 50GB, load stays low as there is not much happening, so even using 20 VM and Docker containers, we do not get too much overhead of using both virtualization and containers. What about trying to spin 2000 or even 10 000 containers… Well, actually without putting load on those containers, measuring it will not be too much useful. We can scale even up to 1 000 000 containers, but what for?