external-secrets/docs/provider/azure-key-vault.md

Azure Key vault

External Secrets Operator integrates with Azure Key vault for secrets, certificates and Keys management.

Authentication

We support authentication with Microsoft Entra identities that can be used as Workload Identity or AAD Pod Identity as well as with Service Principal credentials.

Since the AAD Pod Identity is deprecated, it is recommended to use the Workload Identity authentication.

We support connecting to different cloud flavours azure supports: PublicCloud, USGovernmentCloud, ChinaCloud and GermanCloud. You have to specify the environmentType and point to the correct cloud flavour. This defaults to PublicCloud.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: azure-backend
spec:
  provider:
    azurekv:
      # PublicCloud, USGovernmentCloud, ChinaCloud, GermanCloud
      environmentType: PublicCloud # default

Minimum required permissions are Get over secret and certificate permissions. This can be done by adding a Key Vault access policy:

KUBELET_IDENTITY_OBJECT_ID=$(az aks show --resource-group <AKS_CLUSTER_RG_NAME> --name <AKS_CLUSTER_NAME> --query 'identityProfile.kubeletidentity.objectId' -o tsv)
az keyvault set-policy --name kv-name-with-certs --object-id "$KUBELET_IDENTITY_OBJECT_ID" --certificate-permissions get --secret-permissions get

Service Principal key authentication

A service Principal client and Secret is created and the JSON keyfile is stored in a Kind=Secret. The ClientID and ClientSecret or ClientCertificate (in PEM format) should be configured for the secret. This service principal should have proper access rights to the keyvault to be managed by the operator.

Managed Identity authentication

A Managed Identity should be created in Azure, and that Identity should have proper rights to the keyvault to be managed by the operator.

Use aad-pod-identity to assign the identity to external-secrets operator. To add the selector to external-secrets operator, use podLabels in your values.yaml in case of Helm installation of external-secrets.

If there are multiple Managed Identities for different keyvaults, the operator should have been assigned all identities via aad-pod-identity, then the SecretStore configuration should include the Id of the identity to be used via the identityId field.

{% include 'azkv-secret-store-mi.yaml' %}

Workload Identity

In Microsoft Entra, Workload Identity can be Application, user-assigned Managed Identity and Service Principal.

You can use Azure AD Workload Identity Federation to access Azure managed services like Key Vault without needing to manage secrets. You need to configure a trust relationship between your Kubernetes Cluster and Azure AD. This can be done in various ways, for instance using terraform, the Azure Portal or the az cli. We found the azwi cli very helpful. The Azure Workload Identity Quick Start Guide is also good place to get started.

This is basically a two step process:

1. Create a Kubernetes Service Account (guide)

azwi serviceaccount create phase sa \
  --aad-application-name "${APPLICATION_NAME}" \
  --service-account-namespace "${SERVICE_ACCOUNT_NAMESPACE}" \
  --service-account-name "${SERVICE_ACCOUNT_NAME}"

2. Configure the trust relationship between Azure AD and Kubernetes (guide)

azwi serviceaccount create phase federated-identity \
  --aad-application-name "${APPLICATION_NAME}" \
  --service-account-namespace "${SERVICE_ACCOUNT_NAMESPACE}" \
  --service-account-name "${SERVICE_ACCOUNT_NAME}" \
  --service-account-issuer-url "${SERVICE_ACCOUNT_ISSUER}"

With these prerequisites met you can configure ESO to use that Service Account. You have two options:

Mounted Service Account

You run the controller and mount that particular service account into the pod by adding the label azure.workload.identity/use: "true"to the pod. That grants everyone who is able to create a secret store or reference a correctly configured one the ability to read secrets. This approach is usually not recommended. But may make sense when you want to share an identity with multiple namespaces. Also see our Multi-Tenancy Guide for design considerations.

{% include 'azkv-workload-identity-mounted.yaml' %}

Referenced Service Account

You run the controller without service account (effectively without azure permissions). Now you have to configure the SecretStore and set the serviceAccountRef and point to the service account you have just created. This is usually the recommended approach. It makes sense for everyone who wants to run the controller without Azure permissions and delegate authentication via service accounts in particular namespaces. Also see our Multi-Tenancy Guide for design considerations.

{% include 'azkv-workload-identity.yaml' %}

In case you don't have the clientId when deploying the SecretStore, such as when deploying a Helm chart that includes instructions for creating a Managed Identity using Azure Service Operator next to the SecretStore definition, you may encounter an interpolation problem. Helm lacks dependency management, which means it can create an issue when the clientId is only known after everything is deployed. Although the Service Account can inject clientId and tenantId into a pod, it doesn't support secretKeyRef/configMapKeyRef. Therefore, you can deliver the clientId and tenantId directly, bypassing the Service Account.

The following example demonstrates using the secretRef field to directly deliver the clientId and tenantId to the SecretStore while utilizing Workload Identity authentication.

{% include 'azkv-workload-identity-secretref.yaml' %}

Update secret store

Be sure the azurekv provider is listed in the Kind=SecretStore

{% include 'azkv-secret-store.yaml' %}

NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in clientId and clientSecret with the namespaces where the secrets reside.

Or in case of Managed Identity authentication:

{% include 'azkv-secret-store-mi.yaml' %}

Object Types

Azure Key Vault manages different object types, we support keys, secrets and certificates. Simply prefix the key with key, secret or cert to retrieve the desired type (defaults to secret).

Object Type	Return Value
secret	the raw secret value.
key	A JWK which contains the public key. Azure Key Vault does not export the private key. You may want to use template functions to transform this JWK into PEM encoded PKIX ASN.1 DER format.
certificate	The raw CER contents of the x509 certificate. You may want to use template functions to transform this into your desired encoding

Creating external secret

To create a Kubernetes secret from the Azure Key vault secret a Kind=ExternalSecret is needed.

You can manage keys/secrets/certificates saved inside the keyvault , by setting a "/" prefixed type in the secret name, the default type is a secret. Other supported values are cert and key.

{% include 'azkv-external-secret.yaml' %}

The operator will fetch the Azure Key vault secret and inject it as a Kind=Secret. Then the Kubernetes secret can be fetched by issuing:

kubectl get secret secret-to-be-created -n <namespace> -o jsonpath='{.data.dev-secret-test}' | base64 -d

To select all secrets inside the key vault or all tags inside a secret, you can use the dataFrom directive:

{% include 'azkv-datafrom-external-secret.yaml' %}

To get a PKCS#12 certificate from Azure Key Vault and inject it as a Kind=Secret of type kubernetes.io/tls:

{% include 'azkv-pkcs12-cert-external-secret.yaml' %}

Creating a PushSecret

You can push secrets to Azure Key Vault into the different secret, key and certificate APIs.

Pushing to a Secret

Pushing to a Secret requires no previous setup. with the secret available in Kubernetes, you can simply refer it to a PushSecret object to have it created on Azure Key Vault:

{% include 'azkv-pushsecret-secret.yaml' %}

!!! note In order to create a PushSecret targeting keys, CreateSecret and DeleteSecret actions must be granted to the Service Principal/Identity configured on the SecretStore.

Pushing to a Key

The first step is to generate a valid Private Key. Supported Formats include PRIVATE KEY, RSA PRIVATE KEY AND EC PRIVATE KEY (EC/PKCS1/PKCS8 types). After uploading your key to a Kubernetes Secret, the next step is to create a PushSecret manifest with the following configuration:

{% include 'azkv-pushsecret-key.yaml' %}

!!! note In order to create a PushSecret targeting keys, ImportKey and DeleteKey actions must be granted to the Service Principal/Identity configured on the SecretStore.

Pushing to a Certificate

The first step is to generate a valid P12 certificate. Currently, only PKCS1/PKCS8 types are supported. Currently only password-less P12 certificates are supported.

After uploading your P12 certificate to a Kubernetes Secret, the next step is to create a PushSecret manifest with the following configuration

{% include 'azkv-pushsecret-certificate.yaml' %}

!!! note In order to create a PushSecret targeting keys, ImportCertificate and DeleteCertificate actions must be granted to the Service Principal/Identity configured on the SecretStore.