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Chapter 5. Using Container Storage Interface (CSI)

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5.1. Configuring CSI volumes

The Container Storage Interface (CSI) allows Red Hat OpenShift Service on AWS to consume storage from storage back ends that implement the CSI interface as persistent storage.

Note

Red Hat OpenShift Service on AWS 4 supports version 1.6.0 of the CSI specification.

5.1.1. CSI architecture

CSI drivers are typically shipped as container images. These containers are not aware of Red Hat OpenShift Service on AWS where they run. To use CSI-compatible storage back end in Red Hat OpenShift Service on AWS, the cluster administrator must deploy several components that serve as a bridge between Red Hat OpenShift Service on AWS and the storage driver.

The following diagram provides a high-level overview about the components running in pods in the Red Hat OpenShift Service on AWS cluster.

Architecture of CSI components

It is possible to run multiple CSI drivers for different storage back ends. Each driver needs its own external controllers deployment and daemon set with the driver and CSI registrar.

5.1.1.1. External CSI controllers

External CSI controllers is a deployment that deploys one or more pods with five containers:

  • The snapshotter container watches VolumeSnapshot and VolumeSnapshotContent objects and is responsible for the creation and deletion of VolumeSnapshotContent object.
  • The resizer container is a sidecar container that watches for PersistentVolumeClaim updates and triggers ControllerExpandVolume operations against a CSI endpoint if you request more storage on PersistentVolumeClaim object.
  • An external CSI attacher container translates attach and detach calls from Red Hat OpenShift Service on AWS to respective ControllerPublish and ControllerUnpublish calls to the CSI driver.
  • An external CSI provisioner container that translates provision and delete calls from Red Hat OpenShift Service on AWS to respective CreateVolume and DeleteVolume calls to the CSI driver.
  • A CSI driver container.

The CSI attacher and CSI provisioner containers communicate with the CSI driver container using UNIX Domain Sockets, ensuring that no CSI communication leaves the pod. The CSI driver is not accessible from outside of the pod.

Note

The attach, detach, provision, and delete operations typically require the CSI driver to use credentials to the storage backend. Run the CSI controller pods on infrastructure nodes so the credentials are never leaked to user processes, even in the event of a catastrophic security breach on a compute node.

Note

The external attacher must also run for CSI drivers that do not support third-party attach or detach operations. The external attacher will not issue any ControllerPublish or ControllerUnpublish operations to the CSI driver. However, it still must run to implement the necessary Red Hat OpenShift Service on AWS attachment API.

5.1.1.2. CSI driver daemon set

The CSI driver daemon set runs a pod on every node that allows Red Hat OpenShift Service on AWS to mount storage provided by the CSI driver to the node and use it in user workloads (pods) as persistent volumes (PVs). The pod with the CSI driver installed contains the following containers:

  • A CSI driver registrar, which registers the CSI driver into the openshift-node service running on the node. The openshift-node process running on the node then directly connects with the CSI driver using the UNIX Domain Socket available on the node.
  • A CSI driver.

The CSI driver deployed on the node should have as few credentials to the storage back end as possible. Red Hat OpenShift Service on AWS will only use the node plugin set of CSI calls such as NodePublish/NodeUnpublish and NodeStage/NodeUnstage, if these calls are implemented.

5.1.2. CSI drivers supported by Red Hat OpenShift Service on AWS

Red Hat OpenShift Service on AWS installs certain CSI drivers by default, giving users storage options that are not possible with in-tree volume plugins.

To create CSI-provisioned persistent volumes that mount to these supported storage assets, Red Hat OpenShift Service on AWS installs the necessary CSI driver Operator, the CSI driver, and the required storage class by default. For more details about the default namespace of the Operator and driver, see the documentation for the specific CSI Driver Operator.

The following table describes the CSI drivers that are installed with Red Hat OpenShift Service on AWS and which CSI features they support, such as volume snapshots and resize.

In addition to the drivers listed in the following table, ROSA functions with CSI drivers from third-party storage vendors. Red Hat does not oversee third-party provisioners or the connected CSI drivers and the vendors fully control source code, deployment, operation, and Kubernetes compatibility. These volume provisioners are considered customer-managed and the respective vendors are responsible for providing support. See the Shared responsibilities for Red Hat OpenShift Service on AWS matrix for more information.

Table 5.1. Supported CSI drivers and features in Red Hat OpenShift Service on AWS
CSI driverCSI volume snapshotsCSI cloningCSI resizeInline ephemeral volumes

AWS EBS

 ✅

 ✅

AWS EFS

LVM Storage

 ✅

 ✅

 ✅

5.1.3. Dynamic provisioning

Dynamic provisioning of persistent storage depends on the capabilities of the CSI driver and underlying storage back end. The provider of the CSI driver should document how to create a storage class in Red Hat OpenShift Service on AWS and the parameters available for configuration.

The created storage class can be configured to enable dynamic provisioning.

Procedure

  • Create a default storage class that ensures all PVCs that do not require any special storage class are provisioned by the installed CSI driver. 

    # oc create -f - << EOF
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: <storage-class> 1
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: <provisioner-name> 2
parameters:
EOF
    1
    The name of the storage class that will be created.
    2
    The name of the CSI driver that has been installed.

5.1.4. Example using the CSI driver

The following example installs a default MySQL template without any changes to the template.

Prerequisites

  • The CSI driver has been deployed.
  • A storage class has been created for dynamic provisioning.

Procedure

  • Create the MySQL template: 

    # oc new-app mysql-persistent

    Example output

    --> Deploying template "openshift/mysql-persistent" to project default
...

    # oc get pvc

    Example output

    NAME              STATUS    VOLUME                                   CAPACITY
ACCESS MODES   STORAGECLASS   AGE
mysql             Bound     kubernetes-dynamic-pv-3271ffcb4e1811e8   1Gi
RWO            cinder         3s

5.2. Managing the default storage class

5.2.1. Overview

Managing the default storage class allows you to accomplish several different objectives:

  • Enforcing static provisioning by disabling dynamic provisioning.
  • When you have other preferred storage classes, preventing the storage operator from re-creating the initial default storage class.
  • Renaming, or otherwise changing, the default storage class

To accomplish these objectives, you change the setting for the spec.storageClassState field in the ClusterCSIDriver object. The possible settings for this field are:

  • Managed: (Default) The Container Storage Interface (CSI) operator is actively managing its default storage class, so that most manual changes made by a cluster administrator to the default storage class are removed, and the default storage class is continuously re-created if you attempt to manually delete it.
  • Unmanaged: You can modify the default storage class. The CSI operator is not actively managing storage classes, so that it is not reconciling the default storage class it creates automatically.
  • Removed: The CSI operators deletes the default storage class.

5.2.2. Managing the default storage class using the web console

Prerequisites

  • Access to the Red Hat OpenShift Service on AWS web console.
  • Access to the cluster with cluster-admin privileges.

Procedure

To manage the default storage class using the web console:

  1. Log in to the web console.
  2. Click Administration > CustomResourceDefinitions.
  3. On the CustomResourceDefinitions page, type clustercsidriver to find the ClusterCSIDriver object.
  4. Click ClusterCSIDriver, and then click the Instances tab.
  5. Click the name of the desired instance, and then click the YAML tab.

  6. Add the spec.storageClassState field with a value of Managed, Unmanaged, or Removed.

    Example

    ...
spec:
  driverConfig:
    driverType: ''
  logLevel: Normal
  managementState: Managed
  observedConfig: null
  operatorLogLevel: Normal
  storageClassState: Unmanaged 1
...

    1
    spec.storageClassState field set to "Unmanaged"
  7. Click Save.

5.2.3. Managing the default storage class using the CLI

Prerequisites

  • Access to the cluster with cluster-admin privileges.

Procedure

To manage the storage class using the CLI, run the following command: 

oc patch clustercsidriver $DRIVERNAME --type=merge -p "{\"spec\":{\"storageClassState\":\"${STATE}\"}}" 1
1
Where ${STATE} is "Removed" or "Managed" or "Unmanaged".

Where $DRIVERNAME is the provisioner name. You can find the provisioner name by running the command oc get sc.

5.2.4. Absent or multiple default storage classes

5.2.4.1. Multiple default storage classes

Multiple default storage classes can occur if you mark a non-default storage class as default and do not unset the existing default storage class, or you create a default storage class when a default storage class is already present. With multiple default storage classes present, any persistent volume claim (PVC) requesting the default storage class (pvc.spec.storageClassName=nil) gets the most recently created default storage class, regardless of the default status of that storage class, and the administrator receives an alert in the alerts dashboard that there are multiple default storage classes, MultipleDefaultStorageClasses.

5.2.4.2. Absent default storage class

There are two possible scenarios where PVCs can attempt to use a non-existent default storage class:

  • An administrator removes the default storage class or marks it as non-default, and then a user creates a PVC requesting the default storage class.
  • During installation, the installer creates a PVC requesting the default storage class, which has not yet been created.

In the preceding scenarios, PVCs remain in the pending state indefinitely. To resolve this situation, create a default storage class or declare one of the existing storage classes as the default. As soon as the default storage class is created or declared, the PVCs get the new default storage class. If possible, the PVCs eventually bind to statically or dynamically provisioned PVs as usual, and move out of the pending state.

5.2.5. Changing the default storage class

Use the following procedure to change the default storage class.

For example, if you have two defined storage classes, gp3 and standard, and you want to change the default storage class from gp3 to standard.

Prerequisites

  • Access to the cluster with cluster-admin privileges.

Procedure

To change the default storage class:

  1. List the storage classes: 

    $ oc get storageclass

    Example output

    NAME                 TYPE
gp3 (default)        kubernetes.io/aws-ebs 1
standard             kubernetes.io/aws-ebs

    1
    (default) indicates the default storage class.

  2. Make the desired storage class the default.

    For the desired storage class, set the storageclass.kubernetes.io/is-default-class annotation to true by running the following command: 

    $ oc patch storageclass standard -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "true"}}}'
    Note

    You can have multiple default storage classes for a short time. However, you should ensure that only one default storage class exists eventually.

    With multiple default storage classes present, any persistent volume claim (PVC) requesting the default storage class (pvc.spec.storageClassName=nil) gets the most recently created default storage class, regardless of the default status of that storage class, and the administrator receives an alert in the alerts dashboard that there are multiple default storage classes, MultipleDefaultStorageClasses.

  3. Remove the default storage class setting from the old default storage class.

    For the old default storage class, change the value of the storageclass.kubernetes.io/is-default-class annotation to false by running the following command: 

    $ oc patch storageclass gp3 -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "false"}}}'

  4. Verify the changes: 

    $ oc get storageclass

    Example output

    NAME                 TYPE
gp3                  kubernetes.io/aws-ebs
standard (default)   kubernetes.io/aws-ebs

5.3. AWS Elastic Block Store CSI Driver Operator

5.3.1. Overview

Red Hat OpenShift Service on AWS is capable of provisioning persistent volumes (PVs) using the AWS EBS CSI driver.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned PVs that mount to AWS EBS storage assets, Red Hat OpenShift Service on AWS installs the AWS EBS CSI Driver Operator (a Red Hat operator) and the AWS EBS CSI driver by default in the openshift-cluster-csi-drivers namespace.

5.3.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plugins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give Red Hat OpenShift Service on AWS users storage options, such as volume snapshots, that are not possible with in-tree volume plugins.

Important

Red Hat OpenShift Service on AWS defaults to using the CSI plugin to provision Amazon Elastic Block Store (Amazon EBS) storage.

For information about dynamically provisioning AWS EBS persistent volumes in Red Hat OpenShift Service on AWS, see Persistent storage using Amazon Elastic Block Store.

Additional resources

5.4. Setting up AWS Elastic File Service CSI Driver Operator

Important

This procedure is specific to the AWS EFS CSI Driver Operator (a Red Hat operator), which is only applicable for Red Hat OpenShift Service on AWS 4.10 and later versions.

5.4.1. Overview

Red Hat OpenShift Service on AWS is capable of provisioning persistent volumes (PVs) using the AWS EFS CSI driver.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a CSI Operator and driver.

After installing the AWS EFS CSI Driver Operator, Red Hat OpenShift Service on AWS installs the AWS EFS CSI Operator and the AWS EFS CSI driver by default in the openshift-cluster-csi-drivers namespace. This allows the AWS EFS CSI Driver Operator to create CSI-provisioned PVs that mount to AWS EFS assets.

  • The AWS EFS CSI Driver Operator, after being installed, does not create a storage class by default to use to create persistent volume claims (PVCs). However, you can manually create the AWS EFS StorageClass. The AWS EFS CSI Driver Operator supports dynamic volume provisioning by allowing storage volumes to be created on-demand. This eliminates the need for cluster administrators to pre-provision storage.
  • The AWS EFS CSI driver enables you to create and mount AWS EFS PVs.
Note

Amazon Elastic File Storage (Amazon EFS) only supports regional volumes, not zonal volumes.

5.4.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plugins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give Red Hat OpenShift Service on AWS users storage options, such as volume snapshots, that are not possible with in-tree volume plugins.

5.4.3. Setting up the AWS EFS CSI Driver Operator

  1. Install the AWS EFS CSI Driver Operator (a Red Hat operator).
  2. If you are using Amazon Elastic File Storage (Amazon EFS) with AWS Secure Token Service (STS), configure the AWS EFS CSI driver with STS.
  3. If you are using AWS EFS with AWS Secure Token Service (STS), obtain a role Amazon Resource Name (ARN) for STS. This is required for installing the AWS EFS CSI Driver Operator.
  4. Install the AWS EFS CSI Driver Operator.
  5. Install the AWS EFS CSI Driver.

5.4.3.1. Installing the AWS EFS CSI Driver Operator

The AWS EFS CSI Driver Operator (a Red Hat Operator) is not installed in Red Hat OpenShift Service on AWS by default. Use the following procedure to install and configure the AWS EFS CSI Driver Operator in your cluster.

Prerequisites

  • Access to the Red Hat OpenShift Service on AWS web console.

Procedure

To install the AWS EFS CSI Driver Operator from the web console:

  1. Log in to the web console.

  2. Install the AWS EFS CSI Operator:

    1. Click Operators OperatorHub.
    2. Locate the AWS EFS CSI Operator by typing AWS EFS CSI in the filter box.
    3. Click the AWS EFS CSI Driver Operator button.
    Important

    Be sure to select the AWS EFS CSI Driver Operator and not the AWS EFS Operator. The AWS EFS Operator is a community Operator and is not supported by Red Hat.

    1. On the AWS EFS CSI Driver Operator page, click Install.

    2. On the Install Operator page, ensure that:

      • If you are using AWS EFS with AWS Secure Token Service (STS), in the role ARN field, enter the ARN role copied from the last step of the Obtaining a role Amazon Resource Name for Security Token Service procedure.
      • All namespaces on the cluster (default) is selected.
      • Installed Namespace is set to openshift-cluster-csi-drivers.

    3. Click Install.

      After the installation finishes, the AWS EFS CSI Operator is listed in the Installed Operators section of the web console.

Next steps

5.4.3.2. Configuring AWS EFS CSI Driver Operator with Secure Token Service

This procedure explains how to configure the AWS EFS CSI Driver Operator (a Red Hat operator) with Red Hat OpenShift Service on AWS on AWS Secure Token Service (STS).

Perform this procedure before you have installed the AWS EFS CSI Operator, but not yet installed the AWS EFS CSI driver as part of the Installing the AWS EFS CSI Driver Operator procedure.

Important

If you perform this procedure after installing the driver and creating volumes, your volumes will fail to mount into pods.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.
  • AWS account credentials
  • You have installed the AWS EFS CSI Operator.

Procedure

  1. Prepare the AWS account:

    1. Create an IAM policy JSON file with the following content: 

      {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "elasticfilesystem:DescribeAccessPoints",
        "elasticfilesystem:DescribeFileSystems",
        "elasticfilesystem:DescribeMountTargets",
        "ec2:DescribeAvailabilityZones",
        "elasticfilesystem:TagResource"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "elasticfilesystem:CreateAccessPoint"
      ],
      "Resource": "*",
      "Condition": {
        "StringLike": {
          "aws:RequestTag/efs.csi.aws.com/cluster": "true"
        }
      }
    },
    {
      "Effect": "Allow",
      "Action": "elasticfilesystem:DeleteAccessPoint",
      "Resource": "*",
      "Condition": {
        "StringEquals": {
          "aws:ResourceTag/efs.csi.aws.com/cluster": "true"
        }
      }
    }
  ]
}

    2. Create an IAM trust JSON file with the following content: 

      {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Federated": "arn:aws:iam::<your_aws_account_ID>:oidc-provider/<openshift_oidc_provider>"  1
      },
      "Action": "sts:AssumeRoleWithWebIdentity",
      "Condition": {
        "StringEquals": {
          "<openshift_oidc_provider>:sub": [  2
            "system:serviceaccount:openshift-cluster-csi-drivers:aws-efs-csi-driver-operator",
            "system:serviceaccount:openshift-cluster-csi-drivers:aws-efs-csi-driver-controller-sa"
          ]
        }
      }
    }
  ]
}
      1
      Specify your AWS account ID and the OpenShift OIDC provider endpoint. Obtain the endpoint by running the following command: 
      $ rosa describe cluster \
  -c $(oc get clusterversion -o jsonpath='{.items[].spec.clusterID}{"\n"}') \
  -o yaml | awk '/oidc_endpoint_url/ {print $2}' | cut -d '/' -f 3,4
      2
      Specify the OpenShift OIDC endpoint again.

    3. Create the IAM role: 

      ROLE_ARN=$(aws iam create-role \
  --role-name "<your_cluster_name>-aws-efs-csi-operator" \
  --assume-role-policy-document file://<your_trust_file_name>.json \
  --query "Role.Arn" --output text); echo $ROLE_ARN

      Save the output. You will use it in the next steps.

    4. Create the IAM policy: 

      POLICY_ARN=$(aws iam create-policy \
  --policy-name "<your_rosa_cluster_name>-rosa-efs-csi" \
  --policy-document file://<your_policy_file_name>.json \
  --query 'Policy.Arn' --output text); echo $POLICY_ARN

    5. Attach the IAM policy to the IAM role: 

      $ aws iam attach-role-policy \
  --role-name "<your_rosa_cluster_name>-aws-efs-csi-operator" \
  --policy-arn $POLICY_ARN

  2. Create a Secret YAML file for the driver operator: 

    apiVersion: v1
kind: Secret
metadata:
 name: aws-efs-cloud-credentials
 namespace: openshift-cluster-csi-drivers
stringData:
  credentials: |-
    [default]
    sts_regional_endpoints = regional
    role_arn = <role_ARN> 1
    web_identity_token_file = /var/run/secrets/openshift/serviceaccount/token
    1
    Replace role_ARN with the output you saved while creating the role.

  3. Create the secret: 

    $ oc apply -f aws-efs-cloud-credentials.yaml

    You are now ready to install the AWS EFS CSI driver.

Additional resources

5.4.3.3. Installing the AWS EFS CSI Driver

After installing the AWS EFS CSI Driver Operator (a Red Hat operator) and configuring it with STS, you install the AWS EFS CSI driver.

Prerequisites

  • Access to the Red Hat OpenShift Service on AWS web console.

Procedure

  1. Click Administration CustomResourceDefinitions ClusterCSIDriver.
  2. On the Instances tab, click Create ClusterCSIDriver.

  3. Use the following YAML file: 

    apiVersion: operator.openshift.io/v1
kind: ClusterCSIDriver
metadata:
    name: efs.csi.aws.com
spec:
  managementState: Managed
  4. Click Create.

  5. Wait for the following Conditions to change to a "True" status:

    • AWSEFSDriverNodeServiceControllerAvailable
    • AWSEFSDriverControllerServiceControllerAvailable

5.4.4. Creating the AWS EFS storage class

Storage classes are used to differentiate and delineate storage levels and usages. By defining a storage class, users can obtain dynamically provisioned persistent volumes.

The AWS EFS CSI Driver Operator (a Red Hat operator), after being installed, does not create a storage class by default. However, you can manually create the AWS EFS storage class.

5.4.4.1. Creating the AWS EFS storage class using the console

Procedure

  1. In the Red Hat OpenShift Service on AWS console, click Storage StorageClasses.
  2. On the StorageClasses page, click Create StorageClass.

  3. On the StorageClass page, perform the following steps:

    1. Enter a name to reference the storage class.
    2. Optional: Enter the description.
    3. Select the reclaim policy.
    4. Select efs.csi.aws.com from the Provisioner drop-down list.
    5. Optional: Set the configuration parameters for the selected provisioner.
  4. Click Create.

5.4.4.2. Creating the AWS EFS storage class using the CLI

Procedure

  • Create a StorageClass object: 

    kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: efs-sc
provisioner: efs.csi.aws.com
parameters:
  provisioningMode: efs-ap 1
  fileSystemId: fs-a5324911 2
  directoryPerms: "700" 3
  gidRangeStart: "1000" 4
  gidRangeEnd: "2000" 5
  basePath: "/dynamic_provisioning" 6
    1
    provisioningMode must be efs-ap to enable dynamic provisioning.
    2
    fileSystemId must be the ID of the EFS volume created manually.
    3
    directoryPerms is the default permission of the root directory of the volume. In this example, the volume is accessible only by the owner.
    4 5
    gidRangeStart and gidRangeEnd set the range of POSIX Group IDs (GIDs) that are used to set the GID of the AWS access point. If not specified, the default range is 50000-7000000. Each provisioned volume, and thus AWS access point, is assigned a unique GID from this range.
    6
    basePath is the directory on the EFS volume that is used to create dynamically provisioned volumes. In this case, a PV is provisioned as “/dynamic_provisioning/<random uuid>” on the EFS volume. Only the subdirectory is mounted to pods that use the PV.
    Note

    A cluster admin can create several StorageClass objects, each using a different EFS volume.

5.4.5. Creating and configuring access to EFS volumes in AWS

This procedure explains how to create and configure EFS volumes in AWS so that you can use them in Red Hat OpenShift Service on AWS.

Prerequisites

  • AWS account credentials

Procedure

To create and configure access to an EFS volume in AWS:

  1. On the AWS console, open https://console.aws.amazon.com/efs.

  2. Click Create file system:

    • Enter a name for the file system.
    • For Virtual Private Cloud (VPC), select your Red Hat OpenShift Service on AWS’s' virtual private cloud (VPC).
    • Accept default settings for all other selections.

  3. Wait for the volume and mount targets to finish being fully created:

    1. Go to https://console.aws.amazon.com/efs#/file-systems.
    2. Click your volume, and on the Network tab wait for all mount targets to become available (~1-2 minutes).
  4. On the Network tab, copy the Security Group ID (you will need this in the next step).
  5. Go to https://console.aws.amazon.com/ec2/v2/home#SecurityGroups, and find the Security Group used by the EFS volume.

  6. On the Inbound rules tab, click Edit inbound rules, and then add a new rule with the following settings to allow Red Hat OpenShift Service on AWS nodes to access EFS volumes :

    • Type: NFS
    • Protocol: TCP
    • Port range: 2049

    • Source: Custom/IP address range of your nodes (for example: “10.0.0.0/16”)

      This step allows Red Hat OpenShift Service on AWS to use NFS ports from the cluster.

  7. Save the rule.

5.4.6. Dynamic provisioning for Amazon Elastic File Storage

The AWS EFS CSI driver supports a different form of dynamic provisioning than other CSI drivers. It provisions new PVs as subdirectories of a pre-existing EFS volume. The PVs are independent of each other. However, they all share the same EFS volume. When the volume is deleted, all PVs provisioned out of it are deleted too. The EFS CSI driver creates an AWS Access Point for each such subdirectory. Due to AWS AccessPoint limits, you can only dynamically provision 1000 PVs from a single StorageClass/EFS volume.

Important

Note that PVC.spec.resources is not enforced by EFS.

In the example below, you request 5 GiB of space. However, the created PV is limitless and can store any amount of data (like petabytes). A broken application, or even a rogue application, can cause significant expenses when it stores too much data on the volume.

Using monitoring of EFS volume sizes in AWS is strongly recommended.

Prerequisites

  • You have created Amazon Elastic File Storage (Amazon EFS) volumes.
  • You have created the AWS EFS storage class.

Procedure

To enable dynamic provisioning:

  • Create a PVC (or StatefulSet or Template) as usual, referring to the StorageClass created previously. 

    apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test
spec:
  storageClassName: efs-sc
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 5Gi

If you have problems setting up dynamic provisioning, see Amazon Elastic File Storage troubleshooting.

Additional resources

5.4.7. Creating static PVs with Amazon Elastic File Storage

It is possible to use an Amazon Elastic File Storage (Amazon EFS) volume as a single PV without any dynamic provisioning. The whole volume is mounted to pods.

Prerequisites

  • You have created Amazon EFS volumes.

Procedure

  • Create the PV using the following YAML file: 

    apiVersion: v1
kind: PersistentVolume
metadata:
  name: efs-pv
spec:
  capacity: 1
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteMany
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  csi:
    driver: efs.csi.aws.com
    volumeHandle: fs-ae66151a 2
    volumeAttributes:
      encryptInTransit: "false" 3
    1
    spec.capacity does not have any meaning and is ignored by the CSI driver. It is used only when binding to a PVC. Applications can store any amount of data to the volume.
    2
    volumeHandle must be the same ID as the EFS volume you created in AWS. If you are providing your own access point, volumeHandle should be <EFS volume ID>::<access point ID>. For example: fs-6e633ada::fsap-081a1d293f0004630.
    3
    If desired, you can disable encryption in transit. Encryption is enabled by default.

If you have problems setting up static PVs, see Amazon Elastic File Storage troubleshooting.

5.4.8. Amazon Elastic File Storage security

The following information is important for Amazon Elastic File Storage (Amazon EFS) security.

When using access points, for example, by using dynamic provisioning as described earlier, Amazon automatically replaces GIDs on files with the GID of the access point. In addition, EFS considers the user ID, group ID, and secondary group IDs of the access point when evaluating file system permissions. EFS ignores the NFS client’s IDs. For more information about access points, see https://docs.aws.amazon.com/efs/latest/ug/efs-access-points.html.

As a consequence, EFS volumes silently ignore FSGroup; Red Hat OpenShift Service on AWS is not able to replace the GIDs of files on the volume with FSGroup. Any pod that can access a mounted EFS access point can access any file on it.

Unrelated to this, encryption in transit is enabled by default. For more information, see https://docs.aws.amazon.com/efs/latest/ug/encryption-in-transit.html.

5.4.9. Amazon Elastic File Storage troubleshooting

The following information provides guidance on how to troubleshoot issues with Amazon Elastic File Storage (Amazon EFS):

  • The AWS EFS Operator and CSI driver run in namespace openshift-cluster-csi-drivers.

  • To initiate gathering of logs of the AWS EFS Operator and CSI driver, run the following command: 

    $ oc adm must-gather
[must-gather      ] OUT Using must-gather plugin-in image: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:125f183d13601537ff15b3239df95d47f0a604da2847b561151fedd699f5e3a5
[must-gather      ] OUT namespace/openshift-must-gather-xm4wq created
[must-gather      ] OUT clusterrolebinding.rbac.authorization.k8s.io/must-gather-2bd8x created
[must-gather      ] OUT pod for plug-in image quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:125f183d13601537ff15b3239df95d47f0a604da2847b561151fedd699f5e3a5 created

  • To show AWS EFS Operator errors, view the ClusterCSIDriver status: 

    $ oc get clustercsidriver efs.csi.aws.com -o yaml

  • If a volume cannot be mounted to a pod (as shown in the output of the following command): 

    $ oc describe pod
...
  Type     Reason       Age    From               Message
  ----     ------       ----   ----               -------
  Normal   Scheduled    2m13s  default-scheduler  Successfully assigned default/efs-app to ip-10-0-135-94.ec2.internal
  Warning  FailedMount  13s    kubelet            MountVolume.SetUp failed for volume "pvc-d7c097e6-67ec-4fae-b968-7e7056796449" : rpc error: code = DeadlineExceeded desc = context deadline exceeded 1
  Warning  FailedMount  10s    kubelet            Unable to attach or mount volumes: unmounted volumes=[persistent-storage], unattached volumes=[persistent-storage kube-api-access-9j477]: timed out waiting for the condition
    1
    Warning message indicating volume not mounted.

    This error is frequently caused by AWS dropping packets between an Red Hat OpenShift Service on AWS node and Amazon EFS.

    Check that the following are correct:

    • AWS firewall and Security Groups
    • Networking: port number and IP addresses

5.4.10. Uninstalling the AWS EFS CSI Driver Operator

All EFS PVs are inaccessible after uninstalling the AWS EFS CSI Driver Operator (a Red Hat operator).

Prerequisites

  • Access to the Red Hat OpenShift Service on AWS web console.

Procedure

To uninstall the AWS EFS CSI Driver Operator from the web console:

  1. Log in to the web console.
  2. Stop all applications that use AWS EFS PVs.

  3. Delete all AWS EFS PVs:

    1. Click Storage PersistentVolumeClaims.
    2. Select each PVC that is in use by the AWS EFS CSI Driver Operator, click the drop-down menu on the far right of the PVC, and then click Delete PersistentVolumeClaims.

  4. Uninstall the AWS EFS CSI driver:

    Note

    Before you can uninstall the Operator, you must remove the CSI driver first.

    1. Click Administration CustomResourceDefinitions ClusterCSIDriver.
    2. On the Instances tab, for efs.csi.aws.com, on the far left side, click the drop-down menu, and then click Delete ClusterCSIDriver.
    3. When prompted, click Delete.

  5. Uninstall the AWS EFS CSI Operator:

    1. Click Operators Installed Operators.
    2. On the Installed Operators page, scroll or type AWS EFS CSI into the Search by name box to find the Operator, and then click it.
    3. On the upper, right of the Installed Operators > Operator details page, click Actions Uninstall Operator.

    4. When prompted on the Uninstall Operator window, click the Uninstall button to remove the Operator from the namespace. Any applications deployed by the Operator on the cluster need to be cleaned up manually.

      After uninstalling, the AWS EFS CSI Driver Operator is no longer listed in the Installed Operators section of the web console.

Note

Before you can destroy a cluster (openshift-install destroy cluster), you must delete the EFS volume in AWS. An Red Hat OpenShift Service on AWS cluster cannot be destroyed when there is an EFS volume that uses the cluster’s VPC. Amazon does not allow deletion of such a VPC.

5.4.11. Additional resources

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