Summary:
Online volume expansion is a 2 phase process:
1. The backing storage, in this case the raw file, needs to be resized. (i.e. `truncate -s`)
2. The node should be notified, so that it can both refresh its device capacity (i.e. `losetup -c`) and resize the filesystem (`resize2fs`) accordingly.
Although in our case both steps could be performed on the node itself, for the sake of following the semantics of how volume expansion works, we perform step 1 from the controller, and step 2 from the node.
Also, the `external-resizer` component is added which watches for PVC size updates, and notifies the CSI controller about it.
Test Plan:
Setup:
- Deploy
- Create a rawfile-backed pvc, and attach a Deployment to it
- Keep an eye on `rawfile` pod logs in `kube-system` namespace to see if any errors pop out during all scenarios
Scenario 1:
- Increase the size of the pvc
- Exec into the pod and verify that the volume is resized indeed (using `df`)
Scenario 2:
- Decrease deployment's replica to 0
- Increase the size of the pvc. Wait for a couple of minutes.
- Increase deployment's replica to 1
- Exec into the pod and verify that the volume is resized indeed.
Reviewers: bghadiri, mhyousefi, h.marvi, sina_rad
Reviewed By: bghadiri, mhyousefi, sina_rad
Differential Revision: https://phab.hamravesh.ir/D817
