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Google Cloud Secret Manager

Google Cloud Secret Manager

External Secrets Operator integrates with GCP Secret Manager for secret management.

Authentication

Workload Identity

Your Google Kubernetes Engine (GKE) applications can consume GCP services like Secrets Manager without using static, long-lived authentication tokens. This is our recommended approach of handling credentials in GCP. ESO offers two options for integrating with GKE workload identity: pod-based workload identity and using service accounts directly. Before using either way you need to create a service account - this is covered below.

Creating Workload Identity Service Accounts

You can find the documentation for Workload Identity here. We will walk you through how to navigate it here.

Search the document for this editable values and change them to your values: Note: If you have installed ESO, a serviceaccount has already been created. You can either patch the existing external-secrets SA or create a new one that fits your needs.

  • CLUSTER_NAME: The name of your cluster
  • PROJECT_ID: Your project ID (not your Project number nor your Project name)
  • K8S_NAMESPACE: For us following these steps here it will be es, but this will be the namespace where you deployed the external-secrets operator
  • KSA_NAME: external-secrets (if you are not creating a new one to attach to the deployment)
  • GSA_NAME: external-secrets for simplicity, or something else if you have to follow different naming conventions for cloud resources
  • ROLE_NAME: should be roles/secretmanager.secretAccessor - so you make the pod only be able to access secrets on Secret Manager

Using Service Accounts directly

Let's assume you have created a service account correctly and attached a appropriate workload identity. It should roughly look like this:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: external-secrets
  namespace: es
  annotations:
    iam.gke.io/gcp-service-account: example-team-a@my-project.iam.gserviceaccount.com

You can reference this particular ServiceAccount in a SecretStore or ClusterSecretStore. It's important that you also set the projectID, clusterLocation and clusterName. The Namespace on the serviceAccountRef is ignored when using a SecretStore resource. This is needed to isolate the namespaces properly.

When filling clusterLocation parameter keep in mind if it is Regional or Zonal cluster.

apiVersion: external-secrets.io/v1beta1
kind: ClusterSecretStore
metadata:
  name: gcp-store
spec:
  provider:
    gcpsm:
      projectID: alphabet-123
      auth:
        workloadIdentity:
          # name of the cluster Location, region or zone
          clusterLocation: europe-central2
          # name of the GKE cluster
          clusterName: alpha-cluster-42
          # projectID of the cluster (if omitted defaults to spec.provider.gcpsm.projectID)
          clusterProjectID: my-cluster-project
          # reference the sa from above
          serviceAccountRef:
            name: team-a
            namespace: team-a

You need to give the Google service account the roles/iam.serviceAccountTokenCreator role so it can generate a service account token for you (not necessary in the Pod-based Workload Identity bellow)

Using Pod-based Workload Identity

You can attach a Workload Identity directly to the ESO pod. ESO then has access to all the APIs defined in the attached service account policy. You attach the workload identity by (1) creating a service account with a attached workload identity (described above) and (2) using this particular service account in the pod's serviceAccountName field.

For this example we will assume that you installed ESO using helm and that you named the chart installation external-secrets and the namespace where it lives es like:

helm install external-secrets external-secrets/external-secrets --namespace es

Then most of the resources would have this name, the important one here being the k8s service account attached to the external-secrets operator deployment:

# ...
      containers:
      - image: ghcr.io/external-secrets/external-secrets:vVERSION
        name: external-secrets
        ports:
        - containerPort: 8080
          protocol: TCP
      restartPolicy: Always
      schedulerName: default-scheduler
      serviceAccount: external-secrets
      serviceAccountName: external-secrets # <--- here

The pod now has the identity. Now you need to configure the SecretStore. You just need to set the projectID, all other fields can be omitted.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: gcp-store
spec:
  provider:
    gcpsm:
      projectID: alphabet-123

GCP Service Account authentication

You can use GCP Service Account to authenticate with GCP. These are static, long-lived credentials. A GCP Service Account is a JSON file that needs to be stored in a Kind=Secret. ESO will use that Secret to authenticate with GCP. See here how you manage GCP Service Accounts. After creating a GCP Service account go to IAM & Admin web UI, click ADD ANOTHER ROLE button, add Secret Manager Secret Accessor role to this service account. The Secret Manager Secret Accessor role is required to access secrets.

apiVersion: v1
kind: Secret
metadata:
  name: gcpsm-secret
  labels:
    type: gcpsm
type: Opaque
stringData:
  secret-access-credentials: |-
    {
      "type": "service_account",
      "project_id": "external-secrets-operator",
      "private_key_id": "",
      "private_key": "-----BEGIN PRIVATE KEY-----\nA key\n-----END PRIVATE KEY-----\n",
      "client_email": "test-service-account@external-secrets-operator.iam.gserviceaccount.com",
      "client_id": "client ID",
      "auth_uri": "https://accounts.google.com/o/oauth2/auth",
      "token_uri": "https://oauth2.googleapis.com/token",
      "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
      "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/test-service-account%40external-secrets-operator.iam.gserviceaccount.com"
    }

Update secret store

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

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: gcp-store
  namespace: example
spec:
  provider:
    gcpsm:                                  # gcpsm provider
      auth:
        secretRef:
          secretAccessKeySecretRef:
            name: gcpsm-secret              # secret name containing SA key
            key: secret-access-credentials  # key name containing SA key
      projectID: alphabet-123               # name of Google Cloud project

NOTE: In case of a ClusterSecretStore, Be sure to provide namespace for SecretAccessKeyRef with the namespace of the secret that we just created.

Creating external secret

To create a kubernetes secret from the GCP Secret Manager secret a Kind=ExternalSecret is needed.

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: database-credentials
spec:
  refreshInterval: 1h             # rate SecretManager pulls GCPSM
  secretStoreRef:
    kind: SecretStore
    name: gcp-store               # name of the SecretStore (or kind specified)
  target:
    name: database-credentials    # name of the k8s Secret to be created
    creationPolicy: Owner
  data:
  - secretKey: database_username
    remoteRef:
      key: database_username      # name of the GCPSM secret key
  - secretKey: database_password
    remoteRef:
      key: database_password      # name of the GCPSM secret key

The operator will fetch the GCP Secret Manager 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