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Overwriting User Home Directory Entries

Overwriting user home directory entries with memory-backed volumes

To reduce I/O pressure on the storage backend, you can configure the desktop.directorytomemoryemptydir option to replace specific user subdirectories with in-memory emptyDir volumes. This approach is particularly useful for high-churn directories such as .cache, .local, and .config.

desktop.directorytomemoryemptydir: [ '.cache', '.local', '.config' ]
desktop.directorytomemory: { 'emptyDir': { 'medium': 'Memory', 'sizeLimit': '8Gi' } }

The default value of desktop.directorytomemory is the dictionary { 'emptyDir': { 'medium': 'Memory', 'sizeLimit': '8Gi' } }.

This dictionary applies uniformly to every entry listed in desktop.directorytomemoryemptydir.

Running kubectl describe pod displays the volume mounted for each entry in desktop.directorytomemoryemptydir — in this example, [ '.cache', '.local', '.config' ].

The mounted volumes confirm that each path — /home/fry/.cache, /home/fry/.config, and /home/fry/.local — has been replaced by an in-memory volume.

Mounts:
  [...]
  /home/fry/.cache from cache (rw)
  /home/fry/.config from config (rw)
  /home/fry/.local from local (rw)

Each volume is configured as an emptyDir of type Memory with a SizeLimit of 8Gi, meaning its contents are stored entirely in RAM and are discarded when the pod terminates.

Volumes:
  auth-localaccount-fry:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  auth-localaccount-fry
    Optional:    false
 [...]
  cache:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)
    Medium:     Memory
    SizeLimit:  8Gi
  local:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)
    Medium:     Memory
    SizeLimit:  8Gi
  config:
    Type:       EmptyDir (a temporary directory that shares a pod's lifetime)
    Medium:     Memory
    SizeLimit:  8Gi
[...]

Update the sound container for .config usage

The s-sound container requires read access to the $HOME/.config/pulse/cookie file. If you configure .config as an emptyDir volume, you must explicitly add the config volume to the sound container definition.

  • Update your desktop.pod dictionary to include the config volume in the volume list: 'volumes': [ 'extrausers', 'tmp', 'config', 'log' ]
'sound': { 
    'volumes': [ 'extrausers', 'tmp', 'config', 'log' ],
    'image': 'ghcr.io/abcdesktopio/oc.pulseaudio:4.4',
    'imagePullPolicy': 'Always',
    'enable': True,
    'tcpport': 29788,
    'acl':  { 'permit': [ 'all' ] },
  },

After a user logs in, verify that the s-sound container mounts .config at $HOME/.config:

NAMESPACE=abcdesktop
kubectl  describe pods fry-c33ed  -n $NAMESPACE

In the s-sound container's Mounts section, you should see the following entry:

    Mounts:
      /home/fry/.config from config (rw)
      /tmp from tmp (rw)
      /var/lib/extrausers from extrausers (rw)
      /var/log/desktop from log (rw)