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Azure Key Vault CSI on Azure Red Hat OpenShift

Author: Paul Czarkowski Modified: 10/13/2022

This document is adapted from the Azure Key Vault CSI Walkthrough specifically to run with Azure Red Hat OpenShift (ARO).

Prerequisites

  1. An ARO cluster
  2. The AZ CLI (logged in)
  3. Helm 3.x CLI

Environment Variables

  1. Run this command to set some environment variables to use throughout

    Note if you created the cluster from the instructions linked above these will re-use the same environment variables, or default them to openshift and eastus.

    export KEYVAULT_RESOURCE_GROUP=${AZR_RESOURCE_GROUP:-"openshift"}
    export KEYVAULT_LOCATION=${AZR_RESOURCE_LOCATION:-"eastus"}
    export KEYVAULT_NAME=secret-store-$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 10 | head -n 1)
    export AZ_TENANT_ID=$(az account show -o tsv --query tenantId)
    

Installing the Kubernetes Secret Store CSI

  1. Create an OpenShift Project to deploy the CSI into

    oc new-project k8s-secrets-store-csi
    
  2. Set SecurityContextConstraints to allow the CSI driver to run (otherwise the DaemonSet will not be able to create Pods)

    oc adm policy add-scc-to-user privileged \
      system:serviceaccount:k8s-secrets-store-csi:secrets-store-csi-driver
    
  3. Add the Secrets Store CSI Driver to your Helm Repositories

    helm repo add secrets-store-csi-driver \
      https://kubernetes-sigs.github.io/secrets-store-csi-driver/charts
    
  4. Update your Helm Repositories

    helm repo update
    
  5. Install the secrets store csi driver

    helm install -n k8s-secrets-store-csi csi-secrets-store \
      secrets-store-csi-driver/secrets-store-csi-driver \
      --version v1.0.1 \
      --set "linux.providersDir=/var/run/secrets-store-csi-providers"
    
  6. Check that the Daemonsets is running

    kubectl --namespace=k8s-secrets-store-csi get pods -l "app=secrets-store-csi-driver"
    

    You should see the following

    NAME                                               READY   STATUS    RESTARTS   AGE
    csi-secrets-store-secrets-store-csi-driver-cl7dv   3/3     Running   0          57s
    csi-secrets-store-secrets-store-csi-driver-gbz27   3/3     Running   0          57s
    

Deploy Azure Key Store CSI

  1. Add the Azure Helm Repository

    helm repo add csi-secrets-store-provider-azure \
      https://azure.github.io/secrets-store-csi-driver-provider-azure/charts
    
  2. Update your local Helm Repositories

    helm repo update
    
  3. Install the Azure Key Vault CSI provider

    helm install -n k8s-secrets-store-csi azure-csi-provider \
      csi-secrets-store-provider-azure/csi-secrets-store-provider-azure \
      --set linux.privileged=true --set secrets-store-csi-driver.install=false \
      --set "linux.providersDir=/var/run/secrets-store-csi-providers" \
      --version=v1.0.1
    
  4. Set SecurityContextConstraints to allow the CSI driver to run

    oc adm policy add-scc-to-user privileged \
      system:serviceaccount:k8s-secrets-store-csi:csi-secrets-store-provider-azure
    

Create Keyvault and a Secret

  1. Create a namespace for your application

    oc new-project my-application
    
  2. Create an Azure Keyvault in your Resource Group that contains ARO

    az keyvault create -n ${KEYVAULT_NAME} \
      -g ${KEYVAULT_RESOURCE_GROUP} \
      --location ${KEYVAULT_LOCATION}
    
  3. Create a secret in the Keyvault

    az keyvault secret set \
      --vault-name ${KEYVAULT_NAME} \
      --name secret1 --value "Hello"
    
  4. Create a Service Principal for the keyvault

    Note: If this gives you an error, you may need upgrade your Azure CLI to the latest version.

    export SERVICE_PRINCIPAL_CLIENT_SECRET="$(az ad sp create-for-rbac --skip-assignment --name http://$KEYVAULT_NAME --query 'password' -otsv)"
    
    export SERVICE_PRINCIPAL_CLIENT_ID="$(az ad sp list --display-name http://$KEYVAULT_NAME --query '[0].appId' -otsv)"
    
  5. Set an Access Policy for the Service Principal

    az keyvault set-policy -n ${KEYVAULT_NAME} \
      --secret-permissions get \
      --spn ${SERVICE_PRINCIPAL_CLIENT_ID}
    
  6. Create and label a secret for Kubernetes to use to access the Key Vault

    kubectl create secret generic secrets-store-creds \
      -n my-application \
      --from-literal clientid=${SERVICE_PRINCIPAL_CLIENT_ID} \
      --from-literal clientsecret=${SERVICE_PRINCIPAL_CLIENT_SECRET}
    kubectl -n my-application label secret \
      secrets-store-creds secrets-store.csi.k8s.io/used=true
    

Deploy an Application that uses the CSI

  1. Create a Secret Provider Class to give access to this secret

    cat <<EOF | kubectl apply -f -
    apiVersion: secrets-store.csi.x-k8s.io/v1alpha1
    kind: SecretProviderClass
    metadata:
      name: azure-kvname
      namespace: my-application
    spec:
      provider: azure
      parameters:
        usePodIdentity: "false"
        useVMManagedIdentity: "false"
        userAssignedIdentityID: ""
        keyvaultName: "${KEYVAULT_NAME}"
        objects: |
          array:
            - |
              objectName: secret1
              objectType: secret
              objectVersion: ""
        tenantId: "${AZ_TENANT_ID}"
    EOF
    
  2. Create a Pod that uses the above Secret Provider Class

    cat <<EOF | kubectl apply -f -
    kind: Pod
    apiVersion: v1
    metadata:
      name: busybox-secrets-store-inline
      namespace: my-application
    spec:
      containers:
      - name: busybox
        image: k8s.gcr.io/e2e-test-images/busybox:1.29
        command:
          - "/bin/sleep"
          - "10000"
        volumeMounts:
        - name: secrets-store-inline
          mountPath: "/mnt/secrets-store"
          readOnly: true
      volumes:
        - name: secrets-store-inline
          csi:
            driver: secrets-store.csi.k8s.io
            readOnly: true
            volumeAttributes:
              secretProviderClass: "azure-kvname"
            nodePublishSecretRef:
              name: secrets-store-creds
    EOF
    
  3. Check the Secret is mounted

    kubectl exec busybox-secrets-store-inline -- ls /mnt/secrets-store/
    

    Output should match:

    secret1
    
  4. Print the Secret

    kubectl exec busybox-secrets-store-inline \
      -- cat /mnt/secrets-store/secret1
    

    Output should match:

    Hello
    

Cleanup

  1. Uninstall Helm

    helm uninstall -n k8s-secrets-store-csi azure-csi-provider
    
  2. Delete the app

    oc delete project my-application
    
  3. Delete the Azure Key Vault

    az keyvault delete -n ${KEYVAULT_NAME}
    
  4. Delete the Service Principal

    az ad sp delete --id ${SERVICE_PRINCIPAL_CLIENT_ID}
    

Uninstalling the Kubernetes Secret Store CSI

  1. Delete the secrets store csi driver

    helm delete -n k8s-secrets-store-csi csi-secrets-store
    
  2. Delete the SecurityContextConstraints

    oc adm policy remove-scc-from-user privileged \
      system:serviceaccount:k8s-secrets-store-csi:secrets-store-csi-driver