Storage
This page explains how to install and configure persistent storage on a cluster.
Before you begin
This page assumes you have a working Juju deployed cluster.
Ceph Persistent Volumes
The Canonical Distribution of Kubernetes allows you to connect with durable storage devices such as Ceph. When paired with the Juju Storage feature you can add durable storage easily and across clouds.
Deploy a minimum of three ceph-mon and three ceph-osd units.
juju deploy cs:ceph-mon -n 3
juju deploy cs:ceph-osd -n 3
Relate the units together:
juju add-relation ceph-mon ceph-osd
List the storage pools available to Juju for your cloud:
juju storage-pools
Output:
Name Provider Attrs
ebs ebs
ebs-ssd ebs volume-type=ssd
loop loop
rootfs rootfs
tmpfs tmpfs
Note: This listing is for the Amazon Web Services public cloud. Different clouds may have different pool names.
Add a storage pool to the ceph-osd charm by NAME,SIZE,COUNT:
juju add-storage ceph-osd/0 osd-devices=ebs,10G,1
juju add-storage ceph-osd/1 osd-devices=ebs,10G,1
juju add-storage ceph-osd/2 osd-devices=ebs,10G,1
Next relate the storage cluster with the Kubernetes cluster:
juju add-relation kubernetes-master ceph-mon
We are now ready to enlist Persistent Volumes in Kubernetes which our workloads can consume via Persistent Volume (PV) claims.
juju run-action kubernetes-master/0 create-rbd-pv name=test size=50
This example created a “test” Rados Block Device (rbd) in the size of 50 MB.
Use watch on your Kubernetes cluster like the following, you should see the PV become enlisted and be marked as available:
watch kubectl get pv
Output:
NAME CAPACITY ACCESSMODES STATUS CLAIM REASON AGE
test 50M RWO Available 10s
To consume these Persistent Volumes, your pods will need an associated Persistent Volume Claim with them, and is outside the scope of this README. See the Persistent Volumes documentation for more information.