Configuring containerd storage

Platform9 recommends configuring extra storage for /var/lib/containerd directory. This is the location where all the container images and other containerd metadata is stored.

By Default the PMK Nodelet service has the following behaviour when configuring containerd storage on the nodes:

• If /var/lib/containerd is already mounted on an additional device, then it uses the same mount point.
• if /var/lib/containerd is not mounted, then Nodelet looks for local disks of size >= 100 GB on the node.
  • A disk which is not in use anywhere(not mounted on any path) is looked for and the discovery is stopped as soon as the condition is satisfied and the /var/lib/containerd is mounted to that disk.

Using specific disk for containerd storage

The above mentioned default behaviour can have some undesired consequences such as:

• If the node has multiple unused disks of size >= 100GB and nodelet can use the unintended one, which was supposed to used for some other purpose.

Following flags can be used to specify the disk to be used:

• DISABLE_CONTAINERD_MOUNT: Disable discovery mechanism for free disks during containerd configuration.

  • Example: export DISABLE_CONTAINERD_MOUNT=true

• CONTAINERD_DEVICE: Specify the device that nodelet should use to mount /var/lib/containerd.

  • Example: export CONTAINERD_DEVICE=/dev/sdc1

The above flags need to be specified in /etc/pf9/kube_override.env file on every node of the cluster.

Note: If /var/lib/containerd is already mounted, Nodelet will skip using the configuration present in /etc/pf9/kube_override.env file.