Skip to content

Latest commit

 

History

History
295 lines (226 loc) · 10.7 KB

getting-started.md

File metadata and controls

295 lines (226 loc) · 10.7 KB
Raw

Getting started

These instructions reflect the latest version of the codebase. For instructions on older versions, please see version links under Version Compatibility.

Table of Contents

Step 1: Bringing up a cluster with local disks

Enabling the alpha feature gates

1.10-1.12

If raw local block feature is needed,

$ export KUBE_FEATURE_GATES="BlockVolume=true"

Note: Kubernetes versions prior to 1.10 require several additional feature-gates be enabled on all Kubernetes components, because the persistent local volumes and other features were in alpha.

Option 1: GCE

GCE clusters brought up with clusters/kube-up.sh script in Kubernetes repository will automatically format and mount the requested Local SSDs, so you can deploy the provisioner with the pre-generated deployment spec and skip to step 4, unless you want to customize the provisioner spec or storage classes. We need to download the release from https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.

$ wget https://dl.k8s.io/v1.23.5/kubernetes.tar.gz
$ tar -xzf kubernetes.tar.gz
$ cd kubernetes
$ NODE_LOCAL_SSDS_EXT=<n>,<scsi|nvme>,fs cluster/kube-up.sh
$ cd ../
$ kubectl create -f helm/generated_examples/gce.yaml

Option 2: GKE

GKE clusters will automatically format and mount the requested Local SSDs. Please see GKE documentation for instructions for how to create a cluster with Local SSDs.

Then skip to step 4.

Note: The raw block feature is only supported on GKE Kubernetes alpha clusters.

Option 3: Baremetal environments

  1. Partition and format the disks on each node according to your application's requirements.
  2. Mount all the filesystems under one directory per StorageClass. The directories are specified in a configmap, see below.
  3. Configure the Kubernetes API Server, controller-manager, scheduler, and all kubelets with KUBE_FEATURE_GATES as described above.
  4. If not using the default Kubernetes scheduler policy, the following predicates must be enabled:
    • Pre-1.9: NoVolumeBindConflict
    • 1.9+: VolumeBindingChecker

Option 4: Local test cluster

Kubernetes provides a script to build and start a lightweight local cluster on Linux. You can try to deploy local-volume-provisioner in this cluster and discovery local volumes on your local machine.

  1. Create /mnt/disks directory and mount several volumes into its subdirectories. The example below uses three ram disks to simulate real local volumes:
$ mkdir /mnt/disks
$ for vol in vol1 vol2 vol3; do
    mkdir /mnt/disks/$vol
    mount -t tmpfs $vol /mnt/disks/$vol
done
  1. Run the local cluster.
$ git clone --depth=1 https://github.com/kubernetes/kubernetes
$ cd kubernetes
$ ALLOW_PRIVILEGED=true LOG_LEVEL=5 FEATURE_GATES=$KUBE_FEATURE_GATES hack/local-up-cluster.sh

See running Kubernetes locally for more information.

Option 5: EKS (experimental)

eks-nvme-ssd-provisioner

eks-nvme-ssd-provisioner runs as a DaemonSet and will automatically format and mount the requested local NVMe SSDs.

Note: This project mounts disks in /pv-disks/$uuid. There is a working example of storage local static provisioner resources in the eks-nvme-ssd-provisioner repo.

Using raw block devices directly

You can also mount the nvme instance storage disks directly. You can do this by symlinking the Instance Storage disks for discovery using udev automatically. This has the benefit of not needing an additional component like eks-nvme-ssd-provisioner to be deployed.

The following udev rule will symlink all Instance Storage disks under /dev/disk/kubernetes/<unique id>:

# /etc/udev/rules.d/90-kubernetes-discovery.rules

# Discover Instance Storage disks so kubernetes local provisioner can pick them up from /dev/disk/kubernetes
KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon EC2 NVMe Instance Storage", ATTRS{serial}=="?*", SYMLINK+="disk/kubernetes/nvme-$attr{model}_$attr{serial}", OPTIONS="string_escape=replace"

e.g. you could bring up an eks cluster using eksctl that sets up these udev rules on startup as follows:

apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig
metadata:
  name: cluster-with-storage
  region: eu-central-1
managedNodeGroups:
  - name: storage-nvme
    desiredCapacity: 4
    instanceType: i3.large
    preBootstrapCommands:
      - |
          cat <<EOF > /etc/udev/rules.d/90-kubernetes-discovery.rules
          # Discover Instance Storage disks so kubernetes local provisioner can pick them up from /dev/disk/kubernetes
          KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon EC2 NVMe Instance Storage", ATTRS{serial}=="?*", SYMLINK+="disk/kubernetes/nvme-\\\$attr{model}_\\\$attr{serial}", OPTIONS="string_escape=replace"
          EOF
      - udevadm control --reload && udevadm trigger

You can then use

$ kubectl create -f helm/generated_examples/eks-nvme-ssd.yaml

or use helm with helm/examples/eks-nvme-ssd.yaml

to setup provisioning.

Option 6: AKS

See Local Persistent Volume support on Azure for more information.

Option 7: LKE

LKE clusters can be created with custom Node Pools using the Linode API. For more information, see the LKE Endpoints Collection.

Step 2: Creating a StorageClass (1.9+)

To delay volume binding until pod scheduling and to handle multiple local PVs in a single pod, a StorageClass must to be created with volumeBindingMode set to WaitForFirstConsumer.

$ kubectl create -f deployment/kubernetes/example/default_example_storageclass.yaml

Step 3: Creating local persistent volumes

Option 1: Using the local volume static provisioner

  1. Generate Provisioner's ServiceAccount, Roles, DaemonSet, and ConfigMap spec, and customize it.

    This step uses helm templates to generate the specs. See the helm README for setup instructions. To generate the provisioner's specs using the default values, run:

    helm template ./helm/provisioner > deployment/kubernetes/provisioner_generated.yaml

    You can also provide a custom values file instead:

    helm template ./helm/provisioner --values custom-values.yaml > deployment/kubernetes/provisioner_generated.yaml

  2. Deploy Provisioner

    Once a user is satisfied with the content of Provisioner's yaml file, kubectl can be used to create Provisioner's DaemonSet and ConfigMap.

    $ kubectl create -f deployment/kubernetes/provisioner_generated.yaml

  3. Check discovered local volumes

    Once launched, the external static provisioner will discover and create local-volume PVs.

    For example, if the directory /mnt/disks/ contained one directory /mnt/disks/vol1 then the following local-volume PV would be created by the static provisioner:

    $ kubectl get pv
NAME                CAPACITY    ACCESSMODES   RECLAIMPOLICY   STATUS      CLAIM     STORAGECLASS    REASON    AGE
local-pv-ce05be60   1024220Ki   RWO           Delete          Available             local-storage             26s

$ kubectl describe pv local-pv-ce05be60
Name:		local-pv-ce05be60
Labels:		<none>
Annotations:	pv.kubernetes.io/provisioned-by=local-volume-provisioner-minikube-18f57fb2-a186-11e7-b543-080027d51893
StorageClass:	local-storage
Status:		Available
Claim:
Reclaim Policy:	Delete
Access Modes:	RWO
Capacity:	1024220Ki
NodeAffinity:
  Required Terms:
      Term 0:  kubernetes.io/hostname in [my-node]
Message:
Source:
    Type:	LocalVolume (a persistent volume backed by local storage on a node)
    Path:	/mnt/disks/vol1
Events:		<none>

    The PV described above can be claimed and bound to a PVC by referencing the local-storage storageClassName.

Option 2: Manually create local persistent volume

See Kubernetes documentation for an example PersistentVolume spec.

Step 4: Create local persistent volume claim

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: example-local-claim
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: local-storage

Please replace the following elements to reflect your configuration:

  • "5Gi" with required size of storage volume
  • "local-storage" with the name of storage class associated with the local PVs that should be used for satisfying this PVC

For "Block" volumeMode PVC, which tries to claim a "Block" PV, the following example can be used:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: example-local-claim
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  volumeMode: Block
  storageClassName: local-storage

Note that the only additional field of interest here is volumeMode, which has been set to "Block".