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 Service Principals, Managed Identity and Workload Identity authentication.

To use Managed Identity authentication, you should 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.

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 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.

If there are multiple Managed Identitites 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 idenetity to be used via the identityId field.

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

Workload Identity

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. 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 withour 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' %}

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 Idenetity authentication:

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

Object Types

Azure KeyVault 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 KeyVault 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

to select all secrets inside the key vault , you can use the dataFrom directive

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

The operator will fetch the Azure Key vault secret and inject it as a Kind=Secret

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