Vault CSI Provider
The Vault CSI Provider allows pods to consume Vault secrets using CSI Secrets Store volumes.
The Vault CSI Provider requires the CSI Secret Store Driver to be installed.
At a high level, the CSI Secrets Store driver allows users to create
This object defines which secret provider to use and what secrets to retrieve. When pods requesting CSI volumes
are created, the CSI Secrets Store driver will send the request to the Vault CSI Provider if the provider
vault. The Vault CSI Provider will then use Secret Provider Class specified and the pod's service account to retrieve
the secrets from Vault, and mount them into the pod's CSI volume.
The secret is retrieved from Vault and populated to the CSI secrets store volume during the
This means that pods will be blocked from starting until the secrets have been read from Vault and written to the volume.
The following features are supported by the Vault CSI Provider:
- All Vault secret engines supported.
- Authentication using the requesting pod's service account.
- TLS/mTLS communications with Vault.
- Rendering Vault secrets to files.
- Syncing secrets to Kubernetes secrets to be used as environment variables.
- Installation via Vault Helm
The primary method of authentication with Vault when using the Vault CSI Provider is the service account attached to the pod. At this time no other authentication methods are supported.
For Kubernetes authentication, the service account must be bound to a Vault role and a policy granting access to the secrets desired.
A service account must be present to use the Vault CSI Provider with the Kubernetes authentication method. It is not recommended to bind Vault roles to the default service account provided to pods if no service account is defined.
issuer parameter has been deprecated as of Vault 1.9 and will be removed in a future release.
If running Vault prior to version 1.9, you will likely need to set
configuring Kubernetes authentication for the Vault CSI Provider.
Vault CSI Provider does not use the default token associated with service accounts.
Instead, it creates a token with a short TTL whose lifetime is also bound to the
lifetime of the requesting pod. A key difference between default tokens and
ephemeral tokens is the JWT issuer. Default tokens use
which is the default value that Kubernetes auth will try to validate. However,
ephemeral tokens use the value of
flag as the issuer, which is normally a URL instead. See the Kubernetes auth
ways to check the issuer using the Kubernetes API.
Importantly, this means most common configurations of Vault Agent Injector and Vault CSI Provider cannot share the same Kubernetes auth mount. Vault Agent sidecars will most commonly be configured to authenticate using a long-lived default service account token, with an issuer different to the tokens Vault CSI Provider will create. But one Kubernetes auth mount can only be configured to validate a single issuer value.
The following is an example of a Secret Provider Class using the
--- apiVersion: secrets-store.csi.x-k8s.io/v1alpha1 kind: SecretProviderClass metadata: name: vault-db-creds spec: # Vault CSI Provider provider: vault parameters: # Vault role name to use during login roleName: 'app' # Vault's hostname vaultAddress: 'https://vault:8200' # TLS CA certification for validation vaultCACertPath: '/vault/tls/ca.crt' objects: | - objectName: "dbUsername" secretPath: "database/creds/db-app" secretKey: "username" - objectName: "dbPassword" secretPath: "database/creds/db-app" secretKey: "password" # "objectName" is an alias used within the SecretProviderClass to reference # that specific secret. This will also be the filename containing the secret. # "secretPath" is the path in Vault where the secret should be retrieved. # "secretKey" is the key within the Vault secret response to extract a value from.
Secret Provider Class is a namespaced object in Kubernetes.
An application pod uses the example Secret Provider Class above by mounting it as a CSI volume:
--- apiVersion: apps/v1 kind: Deployment metadata: name: app labels: app: demo spec: selector: matchLabels: app: demo replicas: 1 template: spec: serviceAccountName: app containers: - name: app image: my-app:1.0.0 volumeMounts: - name: 'vault-db-creds' mountPath: '/mnt/secrets-store' readOnly: true volumes: - name: vault-db-creds csi: driver: 'secrets-store.csi.k8s.io' readOnly: true volumeAttributes: secretProviderClass: 'vault-db-creds'
In this example
volumes.csi is created on the application deployment and references
the Secret Provider Class named
Refer to the Vault CSI Provider tutorial to learn how to set up Vault and its depedencies with a Helm chart.