Gluster Meetup June 2016,Bangalore, India
GlusterFS Container
Mohamed Ashiq Liyazudeen
Associate Software Engineer @redhat@ IRC:ashiq on
freenode,github: github.com/MohamedAshiqrh,mailto:
[email protected]
Humble Devassy Chirammal Senior Software Engineer @redhat @ IRC
: hchiramm on freenode, github : github.com/humblec, mailto :
[email protected]
website : humblec.com
Agenda
GlusterFS
Docker
Why containers?
GlusterFS Container
Q&A
GlusterFS
Open-source scale-out distributed file system.
Aggregates various storage servers over network interconnects
into one large parallel network file system.
User space filesystem with no dedicated metadata server that
helps us achieve scalability.
Docker
Docker offers a simple way to package an application and its
runtime dependencies into a single container.
Docker Container uses shared kernel concept and are much more
efficient than hypervisors in system resource terms.
Docker is both a development tool and a runtime environment.
Container Architecture
Source: Docker Inc.
Docker Concepts
Docker Image is a static specification of what the container
should be in runtime, including the application code inside the
container and runtime configuration settings. They are
Read-only.
Docker Concepts
Docker container always starts with an image and is considered
an instantiation of that image.
Why Container?
Shared Kernel
Environment Regardless
Isolation
Minimizes System Drift
Shipping
Cleaner updates and Manageable state change
Storage Hyper-converged Environment Support
GlusterFS Container
Systemd is used in GlusterFS container because gluster needs to
run more than one process in the container.
GlusterFS configuration is made persistent as containers
writable layer is not persistent in case of re-spawn.
Even though GlusterFS can operate on any networking model, we
prefer host networking (--net=host) of Docker for better
performance on storage network.
Steps Breakdown
Pull the image
Prepare the node for GlusterFS configuration persistence(create
directories /var/lib/glusterd, /var/log/glusterfs and
/etc/glusterfs)./var/lib/glusterd volume management files
/var/log/glusterfs gluster log files
/etc/glusterfs glusterd management files
GlusterFS prerequisites(like opening the required port).
Start GlusterFS container.
GlusterFS Container
# docker pull gluster/gluster-centos:gluster3u7_centos7
# mkdir -p /etc/glusterfs /var/lib/glusterd
/var/log/glusterfs
# modprobe dm_snapshot (in case of snapshot)
# docker run --name gluster -d -v
/etc/glusterfs:/etc/glusterfs:z -v
/var/lib/glusterd:/var/lib/glusterd:z -v
/var/log/glusterfs:/var/log/glusterfs:z -v
/sys/fs/cgroup:/sys/fs/cgroup:ro --net=host --privileged=true -v
/dev:/dev gluster/gluster-centos:gluster3u7_centos7
GlusterFS docker run
As seen before its a long command, lets check why all the
options are required.As Gluster needs to run more than one service
in a container, It needs systemd. For systemd to run in a container
--privileged=true.
Host Networking (--net=host) of Docker for better performance on
storage network.
Network options
Docker Network none, adds a container to a container-specific
network stack.
Docker Network bridge, represents the bridge network (default
docker0).
Docker Network host, adds a container on the hosts network
stack.
Persistence of Gluster configuration
-v /etc/glusterfs:/etc/glusterfs:z -v
/var/lib/glusterd:/var/lib/glusterd:z -v
/var/log/glusterfs:/var/log/glusterfs:z
The above ensures that the gluster configuration are persistent,
In the command.
As we mention :z - SELinux labels are automatically reset to
svirt_sandbox_file_t so that the container can interact with the
Host directory.
Gluster Peer Probe
Trusted Storage Pool
References
http://humblec.com/building-glusterfs-in-a-docker-container/
http://humblec.com/gluster_containers_in_kubernetes_cluster/
http://humblec.com/glusterfs-containers-docker-kubernetes-openshift/
https://hub.docker.com/r/gluster/
https://github.com/gluster/docker
https://github.com/gluster/glusterfs-kubernetes-openshift
Thanks !
Q & A
