okd/roles/kube_nfs_volumes

kube_nfs_volumes

This role is useful to export disks as set of Kubernetes persistent volumes. It does so by partitioning the disks, creating ext4 filesystem on each partition, mounting the partitions, exporting the mounts via NFS and adding these NFS shares as NFS persistent volumes to existing Kubernetes installation.

All partitions on given disks are used as the persistent volumes, including already existing partitions! There should be no other data (such as operating system) on the disks!

Requirements

• Running Kubernetes with NFS persistent volume support (on a remote machine).

• Works only on RHEL/Fedora-like distros.

Role Variables

# Options of NFS exports.
nfs_export_options: "*(rw,no_root_squash,insecure,no_subtree_check)"

# Directory, where the created partitions should be mounted. They will be
# mounted as <mount_dir>/sda1 etc.
mount_dir: /exports

# Comma-separated list of disks to partition.
# This role always assumes that all partitions on these disks are used as
# physical volumes.
disks: /dev/sdb,/dev/sdc

# Whether to re-partition already partitioned disks.
# Even though the disks won't get repartitioned on 'false', all existing
# partitions on the disk are exported via NFS as physical volumes!
force: false

# Specification of size of partitions to create. See library/partitionpool.py
# for details.
sizes: 100M

# URL of Kubernetes API server, incl. port.
kubernetes_url: https://10.245.1.2:6443

# Token to use for authentication to the API server
kubernetes_token: tJdce6Fn3cL1112YoIJ5m2exzAbzcPZX

Dependencies

None

Example Playbook

With this playbook, /dev/sdb is partitioned into 100MiB partitions, all of them are mounted into /exports/sdb<N> directory and all these directories are exported via NFS and added as physical volumes to Kubernetes running at https://10.245.1.2:6443.

- hosts: servers
  roles:
    - role: kube_nfs_volumes
      disks: "/dev/sdb"
      sizes: 100M
      kubernetes_url: https://10.245.1.2:6443
      kubernetes_token: tJdce6Fn3cL1112YoIJ5m2exzAbzcPZX

See library/partitionpool.py for details how sizes parameter can be used to create partitions of various sizes.

Full example

Let's say there are two machines, 10.0.0.1 and 10.0.0.2, that we want to use as NFS servers for our Kubernetes cluster, running Kubernetes public API at https://10.245.1.2:6443.

Both servers have three 1 TB disks, /dev/sda for the system and /dev/sdb and /dev/sdc to be partitioned. We want to split the data disks into 5, 10 and 20 GiB partitions so that 10% of the total capacity is in 5 GiB partitions, 40% in 10 GiB and 50% in 20 GiB partitions.

That means, each data disk will have 20x 5 GiB, 40x 10 GiB and 25x 20 GiB partitions.

• Create an inventory file:

  [nfsservers]
  10.0.0.1
  10.0.0.2
  

• Create an ansible playbook, say setupnfs.yaml: ```

  • hosts: nfsservers sudo: yes roles:
    • role: kube_nfs_volumes disks: "/dev/sdb,/dev/sdc" sizes: 5G:10,10G:40,20G:50 force: no kubernetes_url: https://10.245.1.2:6443 kubernetes_token: tJdce6Fn3cL1112YoIJ5m2exzAbzcPZX ```

• Run the playbook:

  ansible-playbook -i inventory setupnfs.yml
  

License

Apache 2.0