Persistent Storage

LambdaStack how-tos - Persistent Storage

  2 minute read  

Kubernetes persistent storage

LambdaStack supports Azure Files and Amazon EFS storage types to use as Kubernetes persistent volumes.

Azure

Infrastructure

LambdaStack creates a storage account with "Standard" tier and locally-redundant storage ("LRS" redundancy option). This storage account contains a file share with the name "k8s".

With the following configuration it is possible to specify storage account name and "k8s" file share quota in GiB.

---
kind: infrastructure/storage-share
name: default
provider: azure
specification:
  quota: 50

Kubernetes

There are a few related K8s objects created such as PersistentVolume, PersistentVolumeClaim and "azure-secret" Secret when specification.storage.enable is set to true. It is possible to control pv/pvc names and storage capacity/request in GiB with the configuration below.

NOTE

It makes no sense to specify greater capacity than Azure file share allows using. In general these values should be the same.

---
kind: configuration/kubernetes-master
name: default
provider: azure
specification:
  storage:
    name: lambdastack-cluster-volume
    enable: true
    capacity: 50

Additional configuration

It is possible to use Azure file shares created by your own. Check documentation for details. Created file shares may be used in different ways. There are appropriate configuration examples below.

NOTE

Before applying configuration, storage access secret should be created

Direct approach

As LambdaStack always creates a file share when provider: azure is used, in this case similar configuration can be used even with specification.storage.enable set to false.

apiVersion: v1
kind: Pod
metadata:
  name: azure1
spec:
  containers:
    - image: busybox
      name: azure
      command: [ "/bin/sh", "-c", "--" ]
      args: [ "while true; do sleep 30; done;" ]
      volumeMounts:
        - name: azure
          mountPath: /mnt/azure
  volumes:
    - name: azure
      azureFile:
        secretName: azure-secret
        shareName: k8s
        readOnly: false
Using persistent volumes
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: lambdastack-cluster-volume
spec:
  storageClassName: azurefile
  capacity:
    storage: 50Gi
    accessModes:
      - "ReadWriteMany"
  azureFile:
    secretName: azure-secret
    shareName: k8s
    readOnly: false
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
    name: lambdastack-cluster-volume-claim
spec:
  storageClassName: azurefile
  volumeName: lambdastack-cluster-volume
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 50Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: azure2
spec:
  containers:
    - image: busybox
      name: azure
      command: [ "/bin/sh", "-c", "--" ]
      args: [ "while true; do sleep 30; done;" ]
      volumeMounts:
        - name: azure
          mountPath: /mnt/azure
  volumes:
    - name: azure
      persistentVolumeClaim:
        claimName: lambdastack-cluster-volume-claim

AWS

Infrastructure

Amazon EFS can be configured using following configuration.

---
kind: infrastructure/efs-storage
provider: aws
name: default
specification:
  encrypted: true
  performance_mode: generalPurpose
  throughput_mode: bursting
  #provisioned_throughput_in_mibps:  # The throughput, measured in MiB/s, that you want to provision for the file system. Only applicable when throughput_mode set to provisioned

Kubernetes

Configuration for AWS supports additional parameter specification.storage.path that allows specifying the path on EFS to be accessed by pods. When specification.storage.enable is set to true, PersistentVolume and PersistentVolumeClaim are created

---
kind: configuration/kubernetes-master
name: default
provider: aws
specification:
  storage:
    name: lambdastack-cluster-volume
    path: /
    enable: true
    capacity: 50

Additional configuration

If provider: aws is specified, EFS storage is always created and can be used with persistent volumes created by the user. It is possible to create a separate EFS and use it. For more information check Kubernetes NFS storage documentation. There is another way to use EFS by Amazon EFS CSI driver but this approach is not supported by LambdaStack's AWS provider.

Persistent volume creation example
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: lambdastack-cluster-volume
spec:
  accessModes:
    - ReadWriteMany
  capacity:
    storage: 100Gi
  mountOptions:
    - hard
    - nfsvers=4.1
    - rsize=1048576
    - wsize=1048576
    - timeo=600
    - retrans=2
  nfs:
    path: /
    server: fs-xxxxxxxx.efs.eu-west-1.amazonaws.com
  storageClassName: defaultfs
  volumeMode: Filesystem