With the influx of cutting edge technologies around Linux Containers, contemporary Software Defined Storage (SDS) platforms face significant opportunities as well as challenges. Containers can overcome some of the differences between Linux distributions which can make SDS platforms easier to deploy. For example, a Ceph installation has to be aware of the differences between Linux distributions and carefully pick various dependent software packages. With the introduction of the ceph-docker project, Ceph daemons are put into Linux Containers and started on the Linux host using docker run, therebysimplifying the deployment and administration overhead. An in-depth look of containerizing SDS storage servers is provided in the talk, using lessons learned with Ceph and GlusterFS as a reference.
Likewise, containers can also make SDS platforms easy to consume for the clients. Putting client software into Linux Containers can eliminate package dependency issues which is especially useful when containerized applications are scheduled on random hosts using container orchestrators. However, there are several non-trivial technical issues associated with filesystem client containerization such as setting proper mount propagation modes so that mount points created by containers are visible by the host and other containers and lifecycle management of long running daemon process (as often seen in FUSE based filesystems). This talk examines these challenges in detail.
Lastly, this talk will explore what SDS platforms can offer to provide a better fit for Linux Containers. For example, Docker relies on SELinux labels to permit containers access filesystems. While SELinux is supported by filesystems such as GlusterFS and NFSv4.2, there are still many filesystems that don't support SELinux yet. This point will be illustrated in the presentation using Kubernetes.
Huamin Chen is a principal software engineer within Red Hat's Emerging Technologies Group. He contributes to Kubernetes and Ceph via his github account rootfs.
