feat: add support for CSI volumes encryption and extraParams.

[mlinares1998]

Hi! 👋

I'm currently using the module to evaluate a potential production cluster, and it's been working fantastically so far!
Great job to everyone involved!

Given the module’s emphasis on encryption by default, I believe it's important to also support encryption at the storage level for block volumes.

This PR introduces support for enabling CSI volume encryption during cluster provisioning, using either a randomly generated or a fixed LUKS2 passphrase.

Additionally, it introduces the ability to define extra parameters in the default StorageClass, in line with the Hetzner CSI driver documentation.

Example kubernetes.tf snippet:

# Enable the HCloud CSI driver
hcloud_csi_enabled = true

# Enable volume encryption; a 32-byte random passphrase is generated by default
hcloud_csi_storage_class_encryption_enabled = true

# Optionally, specify your own encryption key
hcloud_csi_storage_class_encryption_key = "passphrase"

# Define additional StorageClass parameters
hcloud_csi_storage_class_extra_parameters = {
  "csi.storage.k8s.io/fstype" = "xfs"
  "fsFormatOption"            = "-i nrext64=1"
}

This is my first contribution to the module, i hope it aligns with the project's standards.
Looking forward to your feedback!

Best regards,

Reference:
https://github.com/hetznercloud/csi-driver/tree/main/docs/kubernetes#volumes-encrypted-with-luks https://github.com/hetznercloud/csi-driver/tree/main/docs/kubernetes#formatting-options

[M4t7e]

Many thanks @mlinares1998! That looks great! 🙂

Do you think it could be extended to support multiple storage classes?

[mlinares1998]

Many thanks @mlinares1998! That looks great! 🙂

Do you think it could be extended to support multiple storage classes?

Hi!! @M4t7e Thanks for your review!
What do you mean exactly?
Allowing to define multiple storage classes within the module along the default one?

[M4t7e]

Allowing to define multiple storage classes within the module along the default one?

Exactly, that’s what I meant. I can imagine users wanting different storage classes for various use cases.

[mlinares1998]

@M4t7e
I've added in 13f0102 support for defining additional StorageClasses alongside the default one.
Additionally, it's now possible to configure the reclaimPolicy for the default StorageClass as well 😄