What hostpathMapper does exactly?

[felipecrs]

Sorry to ask, but I found no references about it. Two places in the documentation mention that it requires hostpathMapper, but the purpose of it, and what it does, is never explained:

• https://www.vcluster.com/docs/operator/backup#using-velero-inside-vcluster
• https://www.vcluster.com/docs/operator/monitoring-logging#enabling-hostpath-mapper

The helm chart also contains no documentation about it:

• vcluster/charts/k3s/values.yaml

  Lines 132 to 142 in 0332436

  	hostpathMapper:
  	# Image to use for the hostpathMapper
  	# image: ghcr.io/loft-sh/vcluster
  	enabled: false
  	resources: {}
  	# limits:
  	# cpu: 40m
  	# memory: 100Mi
  	# requests:
  	# cpu: 20m
  	# memory: 50Mi

The reason why I ask is because I have some pods that uses some hostPath mounts, and thus I cannot enable isolation with podSecurityStandard: baseline. These pods writes some logs into the node directly through these mounts, and when deleting the vcluster, these logs are left behind the cluster.

Then, I wonder if the hostpathMapper feature can help me "isolate" such behavior, so that when deleting the vcluster these logs would also get deleted from the node.

[ishankhare07]

Hi @felipecrs , the hostPathMapper is basically a feature for enabling logging solutions like fluentd etc. and backup solutions like velero to work inside the vcluster.

You see when the fluentd daemonset agent tries to query the APIServer(virtual) for PodList it gets a list of pods who's name, namespace, UID etc. are different from the actual (physical) pods.

The above details from the physical pods are actually the name of the logfiles for each pod logging on the respective node. So hostpath mapper makes sure to connect those expected and link them with their corresponding so that agents like fluentd, loki, elk etc. can find the correct log files to scrape. Same is the case for velero but in a different dir – /var/kubelet/pods

[felipecrs]

I see, thank you!

[SCLogo]

sorry to ask here. you mention hostpathmapper to able to use velero inside... can you send me a working example?
I have a velero inside and when I delete the pvc and the pv and tries to restore from backup I lost all my data because of the issue:
#1324

Maybe I set something wrong.
Thanks