Hi, The current Docker integration in 0.20 does a "docker pull" from the registry before running any task. This means that your entire Mesos cluster becomes unusable if the registry goes down.
The docs allow you to configure a custom .dockercfg for your tasks to point to a private docker registry. However it is not easy to run an HA docker registry. The docker-registry project recommend using S3 storage buy this is definitely not an option for some people. I know that for regular artifacts, Mesos can use HDFS storage and you can run your HDFS datanodes as Mesos tasks. So even if I attempt to have a docker registry storage in HDFS (which is not supported by docker-registry at the moment), I am stuck on a chicken and egg problem. I want to have as little services outside of Mesos as possible and it is hard to maintain HA services (especially outside of Mesos). Is there anyone running Mesos with Docker in production without S3? I am trying to make all the services outside of Mesos (the "infra" services that are necessary to run Mesos like DNS, Haproxy, Chef server... etc) either HA or not critical for the cluster to run. The docker registry is a new piece of infra outside of Mesos that is critical... Best, Maxime
