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Alternative Datastores

Steward offers the possibility of having a different storage system than etcd thanks to kine integration.

Installing Drivers​

The following make recipes help you to setup alternative Datastore resources. On the Management Cluster, you can use the following commands:

  • MySQL: $ make -C deploy/kine/mysql mariadb

  • PostgreSQL: $ make -C deploy/kine/postgresql postgresql

  • NATS: $ make -C deploy/kine/nats nats

!!! warning "Not for production" The default settings are not production grade: the following scripts are just used to test the Steward usage of different drivers.

Defining a default Datastore upon Steward installation​

Use Helm to install the Steward Operator and make sure it uses a datastore with the proper driver datastore.driver=<MySQL|PostgreSQL|NATS>. Please refer to the Chart available values for more information on supported options.

For example, with a PostgreSQL datastore installed:

helm install steward charts/steward -n steward-system --create-namespace \
  --set steward-etcd.deploy=false \
  --set datastore.driver=PostgreSQL \
  --set datastore.endpoints[0]=postgres-default-rw.steward-system.svc:5432 \
  --set datastore.basicAuth.usernameSecret.name=postgres-default-superuser \
  --set datastore.basicAuth.usernameSecret.namespace=steward-system \
  --set datastore.basicAuth.usernameSecret.keyPath=username \
  --set datastore.basicAuth.passwordSecret.name=postgres-default-superuser \
  --set datastore.basicAuth.passwordSecret.namespace=steward-system \
  --set datastore.basicAuth.passwordSecret.keyPath=password \
  --set datastore.tlsConfig.certificateAuthority.certificate.name=postgres-default-ca \
  --set datastore.tlsConfig.certificateAuthority.certificate.namespace=steward-system \
  --set datastore.tlsConfig.certificateAuthority.certificate.keyPath=ca.crt \
  --set datastore.tlsConfig.certificateAuthority.privateKey.name=postgres-default-ca \
  --set datastore.tlsConfig.certificateAuthority.privateKey.namespace=steward-system \
  --set datastore.tlsConfig.certificateAuthority.privateKey.keyPath=ca.key \
  --set datastore.tlsConfig.clientCertificate.certificate.name=postgres-default-root-cert \
  --set datastore.tlsConfig.clientCertificate.certificate.namespace=steward-system \
  --set datastore.tlsConfig.clientCertificate.certificate.keyPath=tls.crt \
  --set datastore.tlsConfig.clientCertificate.privateKey.name=postgres-default-root-cert \
  --set datastore.tlsConfig.clientCertificate.privateKey.namespace=steward-system \
  --set datastore.tlsConfig.clientCertificate.privateKey.keyPath=tls.key

Once installed, you will be able to create Tenant Control Planes using an alternative datastore.

Defining specific Datastore per Tenant Control Plane​

Each TenantControlPlane can refer to a specific Datastore thanks to the /spec/dataStore field. This allows you to implement your preferred sharding or pooling strategy.

When the said key is omitted, Steward will use the default datastore configured with its CLI argument --datastore.

NATS considerations​

The NATS support is still experimental, mostly because multi-tenancy is NOT supported.

A NATS based DataStore can host one and only one Tenant Control Plane. When a TenantControlPlane is referring to a NATS DataStore already used by another instance, reconciliation will fail and blocked.