nfs-scheme.md

Scheme: NFS

This is the simplest scheme we provide an example for. In this scheme, we NFS export a directory containing subdirectories that are image chroot environments. We directly mount these directories (read-only) and overlay them. While this is the simplest scheme, it is generally the slowest and least scalible.

Creating the image

1. Create the NFS export

   We first need an NFS exported area. Edit /etc/exports and add an entry like:

   /images 192.168.3.0/24(ro,no_root_squash)
   

   export with exportfs -a and verify the export with showmount -e.

   Note that no_root_squash is require for this scheme to function.

2. Create image chroot

   Follow some procedure that provides a subdirectory containing the image files, e.g. a dnf --installroot=... ..., or perhaps a container build and mount. Make sure this chroot is placed under the NFS export directory, e.g. /images/image1.

   The image is now available to the cluster.

Container definition

{
  "name": "image1",
  "command": "/usr/lib/systemd/systemd",
  "state": "running",
  "systemd": true,
  "mount": {
    "kind": "overlay",
    "overlay": {
      "lower": [
        {
          "kind": "nfs",
          "nfs": {
            "path": "/images/image1",
            "host": "192.168.3.253",
            "ro": true
          }
        }
      ]
    }
  }
}