Introduction

democratic-csi implements the csi (container storage interface) spec providing storage for various container orchestration systems (ie: Kubernetes).

The current focus is providing storage via iscsi/nfs from zfs-based storage systems, predominantly FreeNAS / TrueNAS and ZoL on Ubuntu.

The current drivers implement the depth and breadth of the csi spec, so you have access to resizing, snapshots, clones, etc functionality.

democratic-csi is 2 things:

• several implementations of csi drivers
  • freenas-nfs (manages zfs datasets to share over nfs)
  • freenas-iscsi (manages zfs zvols to share over iscsi)
  • freenas-smb (manages zfs datasets to share over smb)
  • zfs-generic-nfs (works with any ZoL installation...ie: Ubuntu)
  • zfs-generic-iscsi (works with any ZoL installation...ie: Ubuntu)
  • zfs-local-ephemeral-inline (provisions node-local zfs datasets)
  • nfs-client (crudely provisions storage using a shared nfs share/directory for all volumes)
• framework for developing csi drivers

If you have any interest in providing a csi driver, simply open an issue to discuss. The project provides an extensive framework to build from making it relatively easy to implement new drivers.

Installation

Predominantly 3 things are needed:

• node prep
• server prep
• deploy the driver into the cluster (helm chart provided with sample values.yaml)

Node Prep

You should install/configure the requirements for both nfs and iscsi.

Follow the instructions here: https://netapp-trident.readthedocs.io/en/stable-v20.04/kubernetes/operations/tasks/worker.html

If you are running Kubernetes with rancher/rke please see the following:

• https://github.com/rancher/rke/issues/1846

freenas-smb

If using with Windows based machines you may need to enable guest access (even if you are connecting with credentiasl)

Set-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters AllowInsecureGuestAuth -Value 1
Restart-Service LanmanWorkstation -Force

zfs-local-ephemeral-inline

This driver provisions node-local ephemeral storage on a per-pod basis. Each node should have an identically named zfs pool created and avaialble to the driver. Note, this is NOT the same thing as using the docker zfs storage driver (although the same pool could be used). No other requirements are necessary.

• https://github.com/kubernetes/enhancements/blob/master/keps/sig-storage/20190122-csi-inline-volumes.md
• https://kubernetes-csi.github.io/docs/ephemeral-local-volumes.html

Server Prep

Server preparation depends slightly on which driver you are using.

FreeNAS (freenas-nfs, freenas-iscsi, freenas-smb)

Ensure the following services are configurged and running:

• ssh (if you use a password for authentication make sure it is allowed)
• ensure zsh, bash, or sh is set as the root shell, csh gives false errors due to quoting
• nfs
• iscsi
• smb

ZoL (zfs-generic-nfs, zfs-generic-iscsi)

Ensure ssh and zfs is installed on the server and that you have installed targetcli.

• yum install targetcli -y
• apt-get -y install targetcli-fb

Helm Installation

helm repo add democratic-csi https://democratic-csi.github.io/charts/
helm repo update
# helm v2
helm search democratic-csi/

# helm v3
helm search repo democratic-csi/

# copy proper values file from https://github.com/democratic-csi/charts/tree/master/stable/democratic-csi/examples
# edit as appropriate
# examples are from helm v2, alter as appropriate for v3

# add --create-namespace for helm v3
helm upgrade \
--install \
--values freenas-iscsi.yaml \
--namespace democratic-csi \
zfs-iscsi democratic-csi/democratic-csi

helm upgrade \
--install \
--values freenas-nfs.yaml \
--namespace democratic-csi \
zfs-nfs democratic-csi/democratic-csi

A note on non standard kubelet paths

Some distrobutions, such as minikube and microk8s uses a non-standard kubelet path. In such cases it is necessary to provide a new kubelet host path, microk8s example below:

microk8s helm upgrade \
  --install \
  --values freenas-nfs.yaml \
  --set node.kubeletHostPath="/var/snap/microk8s/common/var/lib/kubelet"  \
  --namespace democratic-csi \
  zfs-nfs democratic-csi/democratic-csi

Multiple Deployments

You may install multiple deployments of each/any driver. It requires the following:

• Use a new helm release name for each deployment
• Make sure you have a unique csiDriver.name in the values file
• Use unqiue names for your storage classes (per cluster)
• Use a unique parent dataset (ie: don't try to use the same parent across deployments or clusters)

Snapshot Support

Install beta (v1.17+) CRDs (once per cluster):

• https://github.com/kubernetes-csi/external-snapshotter/tree/master/client/config/crd

kubectl apply -f snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl apply -f snapshot.storage.k8s.io_volumesnapshotcontents.yaml
kubectl apply -f snapshot.storage.k8s.io_volumesnapshots.yaml

Install snapshot controller (once per cluster):

• https://github.com/kubernetes-csi/external-snapshotter/tree/master/deploy/kubernetes/snapshot-controller

# replace namespace references to your liking
kubectl apply -f rbac-snapshot-controller.yaml
kubectl apply -f setup-snapshot-controller.yaml

Install democratic-csi as usual with volumeSnapshotClasses defined as appropriate.

• https://kubernetes.io/docs/concepts/storage/volume-snapshots/
• https://github.com/kubernetes-csi/external-snapshotter#usage

Related

• https://github.com/nmaupu/freenas-provisioner
• https://github.com/travisghansen/freenas-iscsi-provisioner
• https://datamattsson.tumblr.com/post/624751011659202560/welcome-truenas-core-container-storage-provider