Updating README.md

Author: Arnar Gauti Ingason

README.md

@@ -1,33 +1,51 @@
 # External PostgreSQL server operator for Kubernetes
 
 ## Features
-* creates a database
-* creates a role with random username and password
-* assigns role to the database
-* if the database exist, it will only create a role
-* drops role when removing CR, assigns all objects to user `postgres`
-* creates a Kubernetes secret with postgres_uri in the same namespace as CR
-
-CR example
+* Creates a database from a CR
+* Creates a role with random username and password from a CR
+* If the database exist, it will only create a role
+* Multiple user roles can own one database
+* Creates Kubernetes secret with postgres_uri in the same namespace as CR
+
+## CRs
 ```yaml
 apiVersion: db.movetokube.com/v1alpha1
 kind: Postgres
 metadata:
   name: my-db
   namespace: app
 spec:
-  # Add fields here
-  database: test-db
+  database: test-db # Name of database created in PostgreSQL
+```
+
+This creates a database called `test-db` and a role `test-db-group` that is set as the owner of the database.
+
+```yaml
+apiVersion: db.movetokube.com/v1alpha1
+kind: PostgresUser
+metadata:
+  name: my-db-user
+  namespace: app
+spec:
+  role: username
+  database: my-db # This references the Postgres CR
   secretName: my-secret
 ```
 
+This creates a user role `username-<hash>` and grants role `test-db-group` to it. Its credentials are put in secret `my-secret-my-db-user`.
+
+`PostgresUser` needs to reference a `Postgres` in the same namespace.
+
+Two `Postgres` referencing the same database can exist in more than one namespace. The last CR referencing a database will drop the group role and transfer database ownership to the role used by the operator.
+
 ## Installation
 
 1. Configure Postgres credentials for the operator in `deploy/operator.yaml` 
 2. `kubectl apply -f deploy/crds/db_v1alpha1_postgres_crd.yaml`
-3. `kubectl apply -f deploy/namespace.yaml`
-4. `kubectl apply -f role.yaml`
-5. `kubectl apply -f role_binding.yaml`
-6. `kubectl apply -f service_account.yaml`
-7. `kubectl apply -f operator.yaml`
+3. `kubectl apply -f deploy/crds/db_v1alpha1_postgresuser_crd.yaml`
+4. `kubectl apply -f deploy/namespace.yaml`
+5. `kubectl apply -f role.yaml`
+6. `kubectl apply -f role_binding.yaml`
+7. `kubectl apply -f service_account.yaml`
+8. `kubectl apply -f operator.yaml`