AWS Elastic File Service CSI Driver Operator - Using Container Storage Interface (CSI) | Storage

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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.

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Overview

Red Hat OpenShift Service on AWS is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for AWS Elastic File Service (EFS).

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.

AWS EFS only supports regional volumes, not zonal volumes.

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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.

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Setting up the AWS EFS CSI Driver Operator

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.
Install the AWS EFS CSI Driver Operator.
Install the AWS EFS CSI Driver.

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Obtaining a role Amazon Resource Name for Security Token Service

This procedure explains how to obtain a role Amazon Resource Name (ARN) to configure the AWS EFS CSI Driver Operator with Red Hat OpenShift Service on AWS on AWS Security Token Service (STS).

Perform this procedure before you install the AWS EFS CSI Driver Operator (see Installing the AWS EFS CSI Driver Operator procedure).

Prerequisites

Access to the cluster as a user with the cluster-admin role.
AWS account credentials

Procedure

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"
        }
      }
    }
  ]
}

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"
          ]
        }
      }
    }
  ]
}

Specify your AWS account ID and the OpenShift OIDC provider endpoint.

Obtain your AWS account ID by running the following command:

$ aws sts get-caller-identity --query Account --output text

Obtain the OpenShift OIDC 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.

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

Copy the role ARN. You will need it when you install the AWS EFS CSI Driver Operator.

Create the IAM policy:

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

Attach the IAM policy to the IAM role:

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

Next steps

Install the AWS EFS CSI Driver Operator.

Additional resources

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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:

Log in to the web console.
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.
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

Install the AWS EFS CSI Driver.

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Installing the AWS EFS CSI Driver

After installing the AWS EFS CSI Driver Operator (a Red Hat operator), you install the AWS EFS CSI driver.

Prerequisites

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

Procedure

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

Use the following YAML file:

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

Click Create.
Wait for the following Conditions to change to a "True" status:
- AWSEFSDriverNodeServiceControllerAvailable
- AWSEFSDriverControllerServiceControllerAvailable

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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.

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Creating the AWS EFS storage class using the console

Procedure

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

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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" (4)
  basePath: "/dynamic_provisioning" (5)

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	`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.
5	`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.

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

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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:

On the AWS console, open https://console.aws.amazon.com/efs.
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.
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).
On the Network tab, copy the Security Group ID (you will need this in the next step).
Go to https://console.aws.amazon.com/ec2/v2/home#SecurityGroups, and find the Security Group used by the EFS volume.
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.
Save the rule.

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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.

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 AWS EFS troubleshooting.

Additional resources

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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 AWS EFS troubleshooting.

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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.

AWS EFS storage CSI usage metrics

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Usage metrics overview

Amazon Web Services (AWS) Elastic File Service (EFS) storage Container Storage Interface (CSI) usage metrics allow you to monitor how much space is used by either dynamically or statically provisioned EFS volumes.

This features is disabled by default, because turning on metrics can lead to performance degradation.

The AWS EFS usage metrics feature collects volume metrics in the AWS EFS CSI Driver by recursively walking through the files in the volume. Because this effort can degrade performance, administrators must explicitly enable this feature.

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Enabling usage metrics using the web console

To enable Amazon Web Services (AWS) Elastic File Service (EFS) Storage Container Storage Interface (CSI) usage metrics using the web console:

Click Administration > CustomResourceDefinitions.
On the CustomResourceDefinitions page next to the Name dropdown box, type clustercsidriver.
Click CRD ClusterCSIDriver.
Click the YAML tab.

Under spec.aws.efsVolumeMetrics.state, set the value to RecursiveWalk.

RecursiveWalk indicates that volume metrics collection in the AWS EFS CSI Driver is performed by recursively walking through the files in the volume.

Example ClusterCSIDriver efs.csi.aws.com YAML file

spec:
    driverConfig:
        driverType: AWS
        aws:
            efsVolumeMetrics:
              state: RecursiveWalk
              recursiveWalk:
                refreshPeriodMinutes: 100
                fsRateLimit: 10

Optional: To define how the recursive walk operates, you can also set the following fields:
- refreshPeriodMinutes: Specifies the refresh frequency for volume metrics in minutes. If this field is left blank, a reasonable default is chosen, which is subject to change over time. The current default is 240 minutes. The valid range is 1 to 43,200 minutes.
- fsRateLimit: Defines the rate limit for processing volume metrics in goroutines per file system. If this field is left blank, a reasonable default is chosen, which is subject to change over time. The current default is 5 goroutines. The valid range is 1 to 100 goroutines.
Click Save.

To disable AWS EFS CSI usage metrics, use the preceding procedure, but for spec.aws.efsVolumeMetrics.state, change the value from RecursiveWalk to Disabled.

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Enabling usage metrics using the CLI

To enable Amazon Web Services (AWS) Elastic File Service (EFS) storage Container Storage Interface (CSI) usage metrics using the CLI:

Edit ClusterCSIDriver by running the following command:
```
$ oc edit clustercsidriver efs.csi.aws.com
```

Under spec.aws.efsVolumeMetrics.state, set the value to RecursiveWalk.

RecursiveWalk indicates that volume metrics collection in the AWS EFS CSI Driver is performed by recursively walking through the files in the volume.

Example ClusterCSIDriver efs.csi.aws.com YAML file

spec:
    driverConfig:
        driverType: AWS
        aws:
            efsVolumeMetrics:
              state: RecursiveWalk
              recursiveWalk:
                refreshPeriodMinutes: 100
                fsRateLimit: 10

Optional: To define how the recursive walk operates, you can also set the following fields:
- refreshPeriodMinutes: Specifies the refresh frequency for volume metrics in minutes. If this field is left blank, a reasonable default is chosen, which is subject to change over time. The current default is 240 minutes. The valid range is 1 to 43,200 minutes.
- fsRateLimit: Defines the rate limit for processing volume metrics in goroutines per file system. If this field is left blank, a reasonable default is chosen, which is subject to change over time. The current default is 5 goroutines. The valid range is 1 to 100 goroutines.
Save the changes to the efs.csi.aws.com object.

To disable AWS EFS CSI usage metrics, use the preceding procedure, but for spec.aws.efsVolumeMetrics.state, change the value from RecursiveWalk to Disabled.

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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

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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:

Log in to the web console.
Stop all applications that use AWS EFS PVs.
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.
Uninstall the AWS EFS CSI driver:

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.
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.

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.

Additional resources

Configuring CSI volumes