Keyvault Csi Driver

Azure Key Vault CSI Driver Skill

Overview

This skill provides guidance for integrating Azure Key Vault with Kubernetes using the Secrets Store CSI Driver. All sensitive data in the your organization clusters is stored in Azure Key Vault and accessed via the CSI driver.

Quick Reference

Environment Configuration

SecretProviderClass Template

apiVersion: secrets-store.csi.x-k8s.io/v1
kind: SecretProviderClass
metadata:
  name: <app>-secrets
  namespace: <namespace>
  labels:
    app.kubernetes.io/name: <app>
    app.kubernetes.io/component: secrets
spec:
  provider: azure
  parameters:
    usePodIdentity: "false"
    useVMManagedIdentity: "true"
    userAssignedIdentityID: "<managed-identity-client-id>"
    keyvaultName: "<keyvault-name>"
    cloudName: "AzurePublicCloud"
    tenantId: "<tenant-id>"
    objects: |
      array:
        - |
          objectName: "<secret-name-in-keyvault>"
          objectType: "secret"
          objectAlias: "<ALIAS_FOR_MOUNT>"
  # Optional: Sync to Kubernetes Secret
  secretObjects:
    - secretName: <k8s-secret-name>
      type: Opaque
      data:
        - objectName: "<ALIAS_FOR_MOUNT>"
          key: "<key-in-k8s-secret>"

Pod Volume Mount

spec:
  containers:
    - name: app
      volumeMounts:
        - name: secrets-store
          mountPath: "/mnt/secrets-store"
          readOnly: true
  volumes:
    - name: secrets-store
      csi:
        driver: secrets-store.csi.k8s.io
        readOnly: true
        volumeAttributes:
          secretProviderClass: "<secretproviderclass-name>"

Common Patterns

Pattern 1: Simple API Token (e.g., Cloudflare)

apiVersion: secrets-store.csi.x-k8s.io/v1
kind: SecretProviderClass
metadata:
  name: cloudflare-api-token-kv
  namespace: external-dns
spec:
  provider: azure
  secretObjects:
    - data:
        - key: cloudflare_api_token
          objectName: cloudflare-api-token
      secretName: cloudflare-api-token
      type: Opaque
  parameters:
    usePodIdentity: "false"
    useVMManagedIdentity: "true"
    userAssignedIdentityID: "<WORKLOAD_IDENTITY_CLIENT_ID>"
    keyvaultName: "kv-example-dev-hlg"
    objects: |
      array:
        - |
          objectName: cloudflare-api-token
          objectType: secret
    tenantId: "<TENANT_ID>"

Pattern 2: Multiple Secrets to Multiple K8s Secrets

apiVersion: secrets-store.csi.x-k8s.io/v1
kind: SecretProviderClass
metadata:
  name: app-secrets
spec:
  provider: azure
  parameters:
    usePodIdentity: "false"
    useVMManagedIdentity: "true"
    userAssignedIdentityID: "<identity>"
    keyvaultName: "<keyvault>"
    tenantId: "<tenant>"
    objects: |
      array:
        - |
          objectName: "app-db-password"
          objectType: "secret"
          objectAlias: "DB_PASSWORD"
        - |
          objectName: "app-redis-password"
          objectType: "secret"
          objectAlias: "REDIS_PASSWORD"
  secretObjects:
    - secretName: app-db-secret
      type: Opaque
      data:
        - objectName: "DB_PASSWORD"
          key: "password"
    - secretName: app-redis-secret
      type: Opaque
      data:
        - objectName: "REDIS_PASSWORD"
          key: "password"

Pattern 3: TLS Certificate

apiVersion: secrets-store.csi.x-k8s.io/v1
kind: SecretProviderClass
metadata:
  name: tls-cert-provider
spec:
  provider: azure
  secretObjects:
    - secretName: tls-secret
      type: kubernetes.io/tls
      data:
        - objectName: tls-cert
          key: tls.crt
        - objectName: tls-key
          key: tls.key
  parameters:
    usePodIdentity: "false"
    useVMManagedIdentity: "true"
    userAssignedIdentityID: "<identity>"
    keyvaultName: "<keyvault>"
    tenantId: "<tenant>"
    objects: |
      array:
        - |
          objectName: my-certificate
          objectType: cert
          objectAlias: tls-cert
        - |
          objectName: my-certificate
          objectType: secret
          objectAlias: tls-key

File Locations

SecretProviderClass files are stored in:

argo-cd-helm-values/kube-addons/<application>/<cluster>/secretproviderclass.yaml

Examples:

• argo-cd-helm-values/kube-addons/defectdojo/example-app-dev/secretproviderclass.yaml
• argo-cd-helm-values/kube-addons/external-dns/example-app-dev/secretproviderclass.yaml
• argo-cd-helm-values/kube-addons/cert-manager/example-app-dev/csi-cloudflare-api-key.yaml

Troubleshooting

Error: 403 Forbidden

Cause: Managed identity lacks Key Vault permissions.

Solution:

# Get identity info from error message, then:
az keyvault set-policy \
  --name "<keyvault-name>" \
  --object-id "<object-id-from-error>" \
  --secret-permissions get list

# Or for RBAC-enabled Key Vaults:
az role assignment create \
  --role "Key Vault Secrets User" \
  --assignee-object-id "<object-id>" \
  --assignee-principal-type ServicePrincipal \
  --scope "/subscriptions/.../Microsoft.KeyVault/vaults/<kv-name>"

Error: Secret Not Found

Cause: Secret name doesn't exist or case mismatch.

Solution:

# List secrets (names are case-sensitive)
az keyvault secret list --vault-name "<kv-name>" --query "[].name" -o tsv

Error: K8s Secret Not Created

Cause: No pod has mounted the CSI volume yet.

Solution: Deploy a pod that mounts the volume. K8s secrets are only created when at least one pod uses the SecretProviderClass.

Error: Pod Stuck in ContainerCreating

Diagnostic:

kubectl describe pod <pod-name> -n <namespace>
kubectl get pods -n kube-system | grep secrets-store
kubectl logs -n kube-system -l app=secrets-store-provider-azure

Scripts

Grant Key Vault Permissions

# Use the helper script
./scripts/grant-keyvault-permissions.sh

# Or quick manual command
az keyvault set-policy \
  --name "kv-example-dev-hlg" \
  --object-id "<object-id>" \
  --secret-permissions get list

Create Secret in Key Vault

az keyvault secret set \
  --vault-name "kv-example-dev-hlg" \
  --name "my-app-secret" \
  --value "secret-value"

List All SecretProviderClasses

kubectl get secretproviderclass -A

Check CSI Driver Status

kubectl get pods -n kube-system | grep secrets-store

Important Notes

1. CSI Volume Required: Even if using secretObjects to sync to K8s secrets, the pod MUST mount the CSI volume.

2. Secret Names: Key Vault secret names are case-sensitive. Use exact match.

3. Object Alias: Use objectAlias for filesystem-safe names when mounting.

4. Namespace Scope: SecretProviderClass is namespace-scoped. Create one per namespace that needs it.

5. RBAC vs Access Policies: Check Key Vault authorization model:

   az keyvault show --name "<kv>" --query "properties.enableRbacAuthorization"
   

Detailed Reference

For complete implementation examples and architecture:

• references/architecture.md - CSI driver architecture
• references/examples.md - Real-world examples
• references/troubleshooting.md - Extended troubleshooting

Gotchas

• K8s Secret doesn't exist until a pod mounts the CSI volume: secretObjects: syncing is lazy — no pod, no Secret. Apps that consume the Secret directly (without mounting the CSI volume themselves) will fail on first deploy until a sibling pod mounts first.
• Workload Identity vs VM Managed Identity are different code paths: useVMManagedIdentity: "true" reads from IMDS; Workload Identity needs usePodIdentity: "false" + useVMManagedIdentity: "false" + serviceAccount annotations. Mixing flags silently falls back to wrong identity.
• Key Vault names are case-sensitive in objects:, K8s keys are not: Secret named MyToken in KV won't be found if you write mytoken in the SPC. The CSI logs say "secret not found" with no hint about casing.
• RBAC vs Access Policy is per-vault, not per-tenant: Some vaults use access policies (az keyvault set-policy), others use Azure RBAC (Key Vault Secrets User role). Check properties.enableRbacAuthorization first — granting the wrong type returns 403 with identical error text.
• TLS certs need two objectType entries: Mounting a cert as tls.crt+tls.key requires objectType: cert (public) AND objectType: secret (full PEM with private key) — both pointing to the same KV cert name. Missing one breaks Ingress TLS silently.
• CSI rotation is opt-in and deploy-only by default: Secrets mounted into pods don't refresh when the KV value changes unless --enable-secret-rotation=true is set on the driver AND the pod is restarted. Long-lived pods serve stale secrets.