Btrfs subvolume

[runningman84]

It would be great if the provisioner could create a btrfs subvolume with quota for each PVC.

This would also give us snapshot and backup functionality using btrfs tools.

[haslersn]

I think this feature would be really great.

[dvonessen]

Hello, I think this is possible. You can use the setup and teardown bash scripts to create subvolumes. Requirements: local-path-provisioner version >= v0.0.15 Steps:

1. kubectl apply -f https://raw.githubusercontent.com/rancher/local-path-provisioner/master/deploy/local-path-storage.yaml to get the local-path-provisioner into you kubernetes cluster.
2. If you want to use btrfs tools, make sure you are using a helper image which has those tools available. By default local-path-provisioner uses busybox docker image. To change this kubectl edit deployments.apps -n local-path-storage local-path-provisioner and edit the container templates command. Append it with e.g. alpine linux image.
3. kubectl edit configmaps local-path-config -n local-path-storage in the data object there edit setup and teardown as wished. eg.

   setup: |-                                                                                        
   #!/bin/sh                                                                                      
   path=$1                                                                                        
   echo "$@"                                                                                      
   apk add btrfs-progs
   btrfs subvolume create ${path}                                                                                                                                                 
   teardown: |-                                                                                     
   #!/bin/sh                                                                                     
   path=$1                                                                                        
   rm -rf ${path}                                                           

   For now it seems not possible to get btrfs subvolume delete ${path} working. I think the helper image hast to run as privileged or need some capabilities.

I hope that helps.

[haslersn]

Is there also an environment variable for the quota in the setup script?

I think btrfs subvolumes still need to be supported directly in local-path-provisioner (or similar project) in order to integrate it with the volume snapshot API, right?

[nikolaishields]

I'm glad to see there is some interest on this topic.

[haslersn]

@dvonessen What needs to be done in order to integrate this with the volume snapshot API?

[nikolaishields]

@dvonessen I can look into the permissions problems, As I've started to look into this issue it appears that there is a btrfs storage driver for docker. I plan on diving into the volume snapshot api later this week, but in the interim I came across the ember-csi which appears to have btrfs support in some capacity. Not sure if either of these will be of use, but they may provide context to solve the problem.

[haslersn]

The btrfs storage driver for docker is about storing images, not volumes.

[MAFLO321]

Any updates on this? What needs to be done?

[dylode]

Any update/plans?

[timoschwarzer]

I have been working on a simple btrfs provisioner: https://github.com/timoschwarzer/btrfs-provisioner I eventually want to add support for automatic node selection, moving volumes between nodes (using btrfs send/receive) and more in the future.