external-secrets/docs/provider-kubernetes.md

External Secrets Operator allows to retrieve in-cluster secrets or from a remote Kubernetes Cluster.

Authentication

It's possible to authenticate against the Kubernetes API using client certificates or a bearer token. Authentication using a service account has not yet been implemented. The operator enforces that exactly one authentication method is used.

NOTE: SelfSubjectAccessReview permission is required for the service account in order to validation work properly.

Example

In-cluster secrets using a Token

1. Create a K8s Secret with a client token for the default service account

apiVersion: v1
kind: Secret
metadata:
  name: mydefaulttoken
  annotations:
    kubernetes.io/service-account.name: default
type: kubernetes.io/service-account-token

2. Create a SecretStore

The Servers url won't be present as it will default to kubernetes.default, add a proper value if needed. In this example the Certificate Authority is fetched using the referenced caProvider.

The auth section indicates that the type token will be used for authentication, it includes the path to fetch the token. Set remoteNamespace to the name of the namespace where your target secrets reside.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: example
spec:
  provider:
    kubernetes:
      server: 
        caProvider: 
          type: Secret
          name: mydefaulttoken
          key: ca.crt
      auth:
        token:
          bearerToken: 
            name: mydefaulttoken
            key: token
      remoteNamespace: default

3. Create the local secret that will be synced

---
apiVersion: v1
kind: Secret
metadata:
  name: secret-example
data:
  extra: YmFyCg==

4. Finally create the ExternalSecret resource

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: example
spec:
  refreshInterval: 1h           
  secretStoreRef:
    kind: SecretStore
    name: example               # name of the SecretStore (or kind specified)
  target:
    name: secret-to-be-created  # name of the k8s Secret to be created
    creationPolicy: Owner
  data:
  - secretKey: extra
    remoteRef:
      key: secret-example
      property: extra

Remote Secret using a Token

1. Create a K8s Secret with the encoded base64 ca and client token.

apiVersion: v1
kind: Secret
metadata:
  name: cluster-secrets
data:
  # Fill with your encoded base64 CA
  certificate-authority-data: Cg==
stringData:
  # Fill with your string Token
  bearerToken: "my-token"

2. Create a SecretStore

The Server section specifies the url of the remote Kubernetes API. In this example the Certificate Authority is fetch using the encoded base64 caBundle.

The auth section indicates that the token type will be used for authentication, it includes the path to fetch the token.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: example
spec:
  provider:
    kubernetes:
      # If not remoteNamesapce is provided, default     namespace is used
      remoteNamespace: remote-namespace
      server:
        url: https://remote.kubernetes.api-server.address
        # Add your encoded base64 to caBundle
        caBundle: Cg==
      auth:
        # Adds referenced bearerToken
        token:
          bearerToken:
            name: cluster-secrets
            key: bearerToken

4. Finally create the ExternalSecret resource

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: example
spec:
  refreshInterval: 1h           
  secretStoreRef:
    kind: SecretStore
    name: example               # name of the SecretStore (or kind specified)
  target:
    name: secret-to-be-created  # name of the k8s Secret to be created
    creationPolicy: Owner
  data:
  - secretKey: extra
    remoteRef:
      key: secret-remote-example
      property: extra