Using GitOps for Stateful Workload Management with vSphere CSI driver on on-premises Kubernetes

Posted August 28, 2024Aug 28

Kubernetes has become the de-facto standard for container orchestration, providing powerful capabilities for deploying and managing stateless workloads. However, users running stateful applications on Kubernetes face unique challenges, especially in VMware environments. A key issue is that the virtual disks used by stateful apps can’t be attached to pods as easily as ephemeral storage. The volumes need to persist even when pods fail and restart. Overall, IT teams need to carefully evaluate challenges and constraints before running stateful workloads on Kubernetes clusters on VMware.

Users who run containerized workloads on Kubernetes clusters on their vSphere environment use Amazon EKS Anywhere (EKS Anywhere). EKS Anywhere on vSphere does not include a default Container Storage Interface (CSI) driver. However, VMware offers a CSI driver with the vSphere Container Storage Plug-in for managing stateful workloads. The vSphere Container Storage Plug-in is a volume plug-in that runs in a native Kubernetes cluster deployed in vSphere and is responsible for provisioning persistent volumes on vSphere storage. An advantage of using this plug-in is snapshot capabilities, which is important for backup and disaster recovery (DR) scenarios.

GitOps manages application and infrastructure deployment so that the system is described declaratively in a Git repository. It is an operational model that allows you to manage the state of multiple Kubernetes clusters by using the best practices of version control, immutable artifacts, and automation. Flux is a GitOps tool that can be used to automate the deployment of applications on Kubernetes as well as manage EKS Anywhere clusters. It works by continuously monitoring the state of a Git repository and applying changes to a cluster.

In this post we demonstrate the process of using GitOps to deploy and manage stateful workloads on your EKS Anywhere cluster on your vSphere environment with vSphere CSI driver.

In this setup, we start with creating vCenter configuration secrets, which are necessary to create storage with vCenter. Then, we install External Secrets Operator to query access keys from AWS Secrets Manager, which are necessary for setting up the vSphere CSI Driver. For this demonstration, we are using Secrets Manager to illustrate the approach, and users can also use any other vault implementation. Next, we configure GitOps through Flux to deploy the vSphere CSI driver manifests from a git repository. Finally, we deploy a stateful workload to validate the backup and restore capabilities of persistent volumes on vCenter storage through our vSphere CSI driver. The outline of this is shown in the preceding diagram.

Prerequisites

Make sure the following prerequisites are complete:

A Linux-based host machine using an Amazon Elastic Compute Cloud (Amazon EC2) instance, an AWS Cloud9 instance, or a local machine with access to your AWS account.
Configure admin access to the EKS Anywhere cluster from the host machine.
Configure IAM Roles for Service Account (IRSA) on the EKS Anywhere cluster.
Install the following tools on the host machine from the previous two steps:
- AWS Command Line Interface (AWS CLI) version 2 to interact with AWS services using CLI commands.
- Helm to deploy and manage Kubernetes applications.
- kubectl to communicate with the Kubernetes API server.
- eksctl and eksctl anywhere to create and manage the EKS Anywhere cluster.
- Git to clone the necessary source repository from GitHub.
- curl to make HTTP requests.
- envsubst to substitute environment variables in shell.
- Flux for creating the Git repository source.

Create the vCenter configuration secrets

The first step in our setup process is to create the necessary vCenter configuration secrets. Let’s export a few vCenter details to the environment variable

export EKSA_ACCOUNT_ID=$(aws sts get-caller-identity --query 'Account' --output text)
export EKSA_OIDC_PROVIDER=<value of $ISSUER_HOSTPATH as configured in IRSA setup>
export EKSA_ES_SERVICE_ACCOUNT="external-secrets-sa"

# Comments reflect example values from the vsphere inventory above - Set Env variables to reflect your vsphere cluster's environment
export VSPHERE_USERNAME=<Your VCenter Admin Username> 
export VSPHERE_PASSWORD=<Your VCenter Admin Password>
export VCENTER_DOMAIN_NAME=<Your Vcenter Server Domain> # sc2-rdops-vm06-dhcp-215-129.eng.vmware.com
export VSPHERE_DATA_CENTER_NAME=<Your Data Center name> # datacenter
export VSPHERE_CLUSTER_NAME=<Your Cluster Name> # vSAN-cluster
export VCENTER_NAME=<Your Vcenter Server # sc2-rdops-vm06-dhcp-215-129
export VSPHERE_IP_ADDRESS=$(getent hosts $VCENTER_DOMAIN_NAME | awk '{ print $1 }')

Next, let’s set up the configuration secrets that are loaded from Secrets Manager:

cat << 'EOF' >> vmwareconf.txt
global: 
  port: 443
  insecureFlag: true
   
# vcenter section
vcenter:
  $VCENTER_NAME:
      server: $VSPHERE_IP_ADDRESS
      user: $VSPHERE_USERNAME
      password: $VSPHERE_PASSWORD
      datacenters:
      - $VSPHERE_DATA_CENTER_NAME
EOF

cat << 'EOF' >> csi-vsphere-vars.txt
[Global]
insecure-flag = "true"
port = "443"

[VirtualCenter "$VSPHERE_IP_ADDRESS"]
cluster-id = "$VSPHERE_CLUSTER_NAME"
user = "$VSPHERE_USERNAME"
password = "$VSPHERE_PASSWORD"
datacenters = "$VSPHERE_DATA_CENTER_NAME"
EOF

Next, let’s load the configuration secrets to Secrets Manager:

export VSPHERE_CONTROLLER_SECRET_ARN=$(aws secretsmanager create-secret \
    --name vsphere.conf \
    --secret-string "$(envsubst < vmwareconf.txt)" | jq -r '.ARN')
    
export CSI_DRIVER_SECRET_ARN=$(aws secretsmanager create-secret \
    --name csi-vsphere.conf \
    --secret-string "$(envsubst < csi-vsphere-vars.txt)" | jq -r '.ARN')

Installing external secrets operator

The next step in our setup process is to setup external secrets to securely access the vCenter Cloud Controller Manager and CSI Driver configuration secrets from Secrets Manager. First, let’s start with creating an AWS Identity and Access Management (IAM) policy and role to allow the cluster to access only the Secrets Manager secrets we created in the previous step:

cat << EOF > vmware-csi-secrets-reader-policy.json
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "secretsmanager:ListSecrets",
                "secretsmanager:GetSecretValue"
            ],
            "Resource": [
                "$VSPHERE_CONTROLLER_SECRET_ARN",
                "$CSI_DRIVER_SECRET_ARN"
            ]
        }
    ]
}
EOF

aws iam create-policy \
  --policy-name vmware-csi-secrets-reader \
  --policy-document file://vmware-csi-secrets-reader-policy.json

export POLICY_ARN=$(aws iam list-policies \
    --query 'Policies[?PolicyName==`vmware-csi-secrets-reader`].Arn' \
    --output text)

cat << EOF > secrets-manager-trust-policy.json
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Federated": "arn:aws:iam::$EKSA_ACCOUNT_ID:oidc-provider/$EKSA_OIDC_PROVIDER"
            },
            "Action": "sts:AssumeRoleWithWebIdentity",
            "Condition": {
                "StringLike": {
                   "$EKSA_OIDC_PROVIDER:sub": [
                     "system:serviceaccount:kube-system:$EKSA_ES_SERVICE_ACCOUNT",
                     "system:serviceaccount:vmware-system-csi:$EKSA_ES_SERVICE_ACCOUNT"
                    ]
                }
            }
        }
    ]
}
EOF
            

export ES_ROLEARN=$(aws iam create-role --role-name ${EKSA_ES_SERVICE_ACCOUNT}-role \
    --assume-role-policy-document file://secrets-manager-trust-policy.json \
    --query Role.Arn --output text)
          
aws iam attach-role-policy --role-name ${EKSA_ES_SERVICE_ACCOUNT}-role \
    --policy-arn $POLICY_ARN

Next, we deploy external-secrets through Helm to sync secrets between Secrets Manager and EKS Anywhere cluster.

helm repo add external-secrets https://charts.external-secrets.io
helm install external-secrets \
external-secrets/external-secrets \
-n external-secrets \
--create-namespace

Next, let’s verify if external-secrets has been successfully deployed and all pods are ready:

> kubectl get pods -n external-secrets

NAME                                                              READY  STATUS   RESTARTS  AGE
pod/external-secrets-5477599d89-7spkg                             1/1    Running  0         100s
pod/external-secrets-cert-controller-6cc64794fc-5czqj             1/1    Running  0         100s
pod/external-secrets-webhook-55555fc4fd-mncm5                     1/1    Running  0         100s

To use IRSA for our secrets retrieval we need a service account in each namespace using external-secrets to assume that role. Since one of the service accounts resides in the vmware-system-csi namespace, we also create that now:

kubectl create ns vmware-system-csi
cat << EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: ${EKSA_ES_SERVICE_ACCOUNT}
  namespace: kube-system
  annotations:
    eks.amazonaws.com/role-arn: ${ES_ROLEARN}
    eks.amazonaws.com/audience: "sts.amazonaws.com"
    eks.amazonaws.com/sts-regional-endpoints: "true"
    eks.amazonaws.com/token-expiration: "86400"
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: ${EKSA_ES_SERVICE_ACCOUNT}
  namespace: vmware-system-csi
  annotations:
    eks.amazonaws.com/role-arn: ${ES_ROLEARN}
    eks.amazonaws.com/audience: "sts.amazonaws.com"
    eks.amazonaws.com/sts-regional-endpoints: "true"
    eks.amazonaws.com/token-expiration: "86400"
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: ${EKSA_ES_SERVICE_ACCOUNT}-cluster-role
rules:
  - apiGroups:
      - ""
    resources:
      - nodes
      - nodes/proxy
      - services
      - endpoints
      - pods
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - extensions
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
  - nonResourceURLs:
      - /metrics
    verbs:
      - get

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: ${EKSA_ES_SERVICE_ACCOUNT}-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ${EKSA_ES_SERVICE_ACCOUNT}-role
subjects:
  - kind: ServiceAccount
    name: ${EKSA_ES_SERVICE_ACCOUNT}
    namespace: kube-system
  - kind: ServiceAccount
    name: ${EKSA_ES_SERVICE_ACCOUNT}
    namespace: vmware-system-csi
EOF

Next, let’s create the ClusterSecretStore which is a scoped SecretStore that can be referenced by all ExternalSecrets from all namespaces

cat << EOF | kubectl apply -f -
apiVersion: external-secrets.io/v1beta1
kind: ClusterSecretStore
metadata:
  name: eksa-secret-store
spec:
  provider:
    aws:  # set secretStore provider to AWS.
      service: SecretsManager # Configure service to be Secrets Manager
      region: us-west-2   # Region where the secret is.
      auth:
        jwt:
          serviceAccountRef:
            name: ${EKSA_ES_SERVICE_ACCOUNT}
EOF

Verify the ClusterSecretStore status using the following command:

> kubectl get clustersecretstore eksa-secret-store

NAME                AGE     STATUS   CAPABILITIES   READY
eksa-secret-store   2m38s   Valid    ReadWrite      True

Configure GitOps with Flux to install Cloud Controller Manager and vSphere CSI Driver

Note that you can skip flux install step can be skipped if you are already using GitOps enabled EKS Anywhere cluster, the EKS Anywhere installation process installs Flux on your behalf.

We use GitOps sync through Flux to handle the deployment of the CSI driver into our EKS Anywhere cluster. Deploy Flux in your EKS Anywhere cluster using the following command

flux install

flux create source git vmware-csi \
  --url=https://github.com/aws-samples/containers-blog-maelstrom \
  --branch=main
  
flux create kustomization csi-driver-main \
  --source=Gitrepository/vmware-csi \
  --path="./vmware-csi-driver-gitops" \
  --prune=true \
  --interval=1m
  --namespace=flux-system

Verify that the CSI driver installation is successful

Check that the cloud controller manager and CSI driver were installed successfully and that the Storage class was created

> kubectl get pods -n kube-system -l name=vsphere-cloud-controller-manager

NAME                                         READY   STATUS     RESTARTS    AGE
pod/vsphere-cloud-controller-manager-5mcm7   1/1     Running    0           5m58s
pod/vsphere-cloud-controller-manager-9zqgq   1/1     Running    0           5m58s
pod/vsphere-cloud-controller-manager-rhgm9   1/1     Running    0           5m58s
> kubectl get pods -n vmware-system-csi

NAME                                          READY   STATUS    RESTARTS        AGE
pod/vsphere-csi-controller-84bb459bd5-8llmm   7/7     Running   0               3m33s
pod/vsphere-csi-controller-84bb459bd5-mh922   7/7     Running   0               3m33s
pod/vsphere-csi-controller-84bb459bd5-vrfkw   7/7     Running   0               3m33s
pod/vsphere-csi-node-g6jfr                    3/3     Running   1 (3m20s ago)   3m33s
pod/vsphere-csi-node-gmlpd                    3/3     Running   2 (3m19s ago)   3m33s
pod/vsphere-csi-node-lmfvq                    3/3     Running   1 (3m21s ago)   3m33s
pod/vsphere-csi-node-s4cdt                    3/3     Running   2 (3m20s ago)   3m33s
pod/vsphere-csi-node-xqj7z                    3/3     Running   1 (3m20s ago)   3m33s
pod/vsphere-csi-node-z6rbp                    3/3     Running   2 (3m20s ago)   3m33s
> kubectl get sc

NAME                  PROVISIONER              RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
vmware-sc (default)   csi.vsphere.vmware.com   Delete          Immediate           false                  4h42m

Verify GitOps deployment of sample stateful workload along with backup and restore

Finally, we validate our GitOps setup, which deployed a sample stateful workload along with validating the backup and restore capabilities with our deployed vSphere CSI driver. This sample stateful workload has deployed a sample app, which created a volume and then created a snapshot.

> kubectl get pods -l job-name=app

NAME            READY   STATUS    RESTARTS   AGE
pod/app-4677h   1/1     Running   0          3m1s

For managing storage for stateful workloads, the vSphere CSI driver uses two API resources: PersistentVolume (PV) and PersistentVolumeClaim (PVC) of PersistentVolume subsystem. A PVC is a request for storage by a user. It is similar to a Pod. Pods consume node resources and PVCs consume PV resources. Pods can request specific levels of resources (CPU and memory). Claims can request specific size and access modes (such as they can be mounted ReadWriteOnce, ReadOnlyMany, ReadWriteMany, or ReadWriteOncePod, see AccessModes). A PV is a piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes. It is a resource in the cluster just like a node is a cluster resource. PVs are volume plugins like volumes, but they have a lifecycle independent of any individual pod that uses the PV. This API object captures the details of the implementation of the storage, be that NFS, iSCSI, or a cloud-provider-specific storage system.

Run the following commands to see the pod of sample stateful workload along with the PVC, which is bound to our vmware-sc storage class and a PV dynamically provisioned with vCenter storage:

> kubectl get pv

NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                      STORAGECLASS   REASON   AGE
pvc-5ec73b4b-3d1e-41a6-8cac-5502094462eb   4Gi        RWO            Delete           Bound    default/vmware-csi-claim   vmware-sc               44s

> kubectl get pvc

NAME               STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
vmware-csi-claim   Bound    pvc-5ec73b4b-3d1e-41a6-8cac-5502094462eb   4Gi        RWO            vmware-sc      114s

Figure 2: vCenter storage UI showing the test workload’s volume

Similar to how API resources PersistentVolume and PersistentVolumeClaim are used to provision volumes, VolumeSnapshotContent and VolumeSnapshot API resources are provided to create volume snapshots.

A VolumeSnapshotContent is a snapshot taken from a volume in the cluster and it is a resource in the cluster just like a PV is a cluster resource. A VolumeSnapshot is a request for a snapshot and it is similar to a PersistentVolumeClaim. Next, let’s check on the VolumeSnapshot, which is a point-in-time snapshot of our volume, which can be used for restoring the storage for the stateful workload

> kubectl get volumesnapshot 

NAME                         READYTOUSE   SOURCEPVC          SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS              SNAPSHOTCONTENT                                    CREATIONTIME   AGE
vmware-csi-volume-snapshot   true         vmware-csi-claim                           4Gi           vmware-csi-snapshotclass   snapcontent-6034c162-e256-4557-b0b9-08f545d723a6   3m35s          4m8s

Finally, let’s validate the restore operation on the stateful workload by creating a workload that uses the created point-in-time snapshot using the following commands:

> kubectl get pods -l kustomize.toolkit.fluxcd.io/name=storage-tester

NAME          READY   STATUS    RESTARTS   AGE
app-restore   1/1     Running   0          4m6s

With that restored pod created we can now see that an additional volume has been created, both in our vCenter UI and on our cluster by running the following command again:

> kubectl get pv

NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                               STORAGECLASS   REASON   AGE
pvc-5ec73b4b-3d1e-41a6-8cac-5502094462eb   4Gi        RWO            Delete           Bound    default/vmware-csi-claim            vmware-sc               13m
pvc-b0f57d0c-ca93-45a4-9ea3-b7adc1c0f096   4Gi        RWO            Delete           Bound    default/restored-vmware-csi-claim   vmware-sc               2s

Figure 3: vCenter storage UI showing the snapshot restore test workload’s volume

Cleaning up

To avoid incurring future charges, clean up the EKS Anywhere cluster resources and AWS resources created during the lab:

# clean up EKSA resources
flux delete kustomization -n flux-system csi-driver-main
kubectl delete sc vmware-sc
kubectl delete clustersecretstore eksa-secret-store
kubectl delete clusterrolebinding ${EKSA_ES_SERVICE_ACCOUNT}-role-binding
kubectl delete sa ${EKSA_ES_SERVICE_ACCOUNT} -n kube-system
kubectl delete sa ${EKSA_ES_SERVICE_ACCOUNT} -n vmware-system-csi
kubectl delete ns vmware-system-csi
kubectl delete secret snapshot-webhook-certs -n kube-system
helm uninstall external-secrets -n external-secrets
rm -fv ./vmwareconf.txt ./csi-vsphere-vars.txt ./vmware-csi-secrets-reader-policy.json ./secrets-manager-trust-policy.json 
kubectl delete ns external-secrets
flux uninstall

# clean up AWS resources

aws iam detach-role-policy --role-name ${EKSA_ES_SERVICE_ACCOUNT}-role \
    --policy-arn $POLICY_ARN
aws iam delete-policy \
    --policy-arn $POLICY_ARN
aws iam delete-role \
    --role-name ${EKSA_ES_SERVICE_ACCOUNT}-role

aws secretsmanager delete-secret \
    --region ${AWS_REGION} \
    --secret-id $VSPHERE_CONTROLLER_SECRET_ARN \
    --recovery-window-in-days=7
aws secretsmanager delete-secret \
    --region ${AWS_REGION} \
    --secret-id $CSI_DRIVER_SECRET_ARN \
    --recovery-window-in-days=7

Conclusion

In this post, we demonstrated the process of using GitOps to deploy a vSphere CSI driver on your EKS Anywhere cluster on your vSphere environment. Furthermore, we demonstrated the process of deploying a stateful workload to our EKS Anywhere cluster using vSphere CSI driver. Then, we demonstrated the underlying process of persistent volume claim and persistent volume creation with stateful workload, which dynamically created a storage on vCenter storage. Finally, we backed up the volume by creating a point-in-time snapshot of the volume and performed a restore operation of the stateful workload with the created point-in-time snapshot. Users looking to run stateful workloads on EKS Anywhere clusters on vSphere can seamlessly follow this approach to operate stateful workloads at scale.

To learn more about managing your EKS Anywhere environment, check the following resources:

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Using GitOps for Stateful Workload Management with vSphere CSI driver on on-premises Kubernetes

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