We would like to show what we are doing with mesos at Allegro. Allegro is the largest retail and auction site in Poland. Mesos is our main production system (right now one thousand CPUs big) for deploying microservices. During the presentation we are going to share our experience from around 1 year of setting automation of entire clusters that integrate with our cloud ecosystem. The stack we are going to talk about is based on: Zookeeper, Terraform, Marathon, Puppet, OpenStack, Nginx, Graphite, Grafana and many more. We would like to show how these tools are used in our daily workflow to cope with our developers needs. There will be a few points about size and problems encountered along the road and some major achievements in operating Mesos in production at scale in Allegro. We are going to show a demo of our production environment to picture our daily workflow with mesos environment.