Configure Vault dynamic database credentials for PostgreSQL

Steps

1. Enable the database secrets engine: vault secrets enable database
2. Configure a connection named for your database by writing to /v1/database/config/CONN_NAME with a plugin_name of postgresql-database-plugin, the connection_url (using a high-privilege account for credential management), and the list of allowed_roles
3. Create a role at /v1/database/roles/ROLE_NAME specifying db_name, creation_statements (a SQL template using Vault's name and password placeholders), default_ttl, and max_ttl
4. Applications request credentials with vault read database/creds/ROLE_NAME; Vault creates a unique PostgreSQL user and returns username and password with a lease
5. Configure your application to renew the lease before expiry using the Vault SDK or agent; on renewal failure, re-request new credentials and update the connection pool
6. Set up a Vault policy granting the application identity read access to database/creds/ROLE_NAME and deny access to database/config/*