Multi-tenancy and dynamic schema selection

Recently, several people asked about implementing dynamic schema selection to enable schema-base multi-tenancy, where tenant isolation is achieved via DDL Schemas. (If you are not familiar with DDL schemas then you can learn the basics e.g. in PostgreSQL docs).

I am opening this Epic to do discuss possible solutions, implement necessary improvements and document how to implement multi-tenancy, possibly including an example app.

Related discussions:

• Loopback 4, Model, PostgresDB schema name https://github.com/strongloop/loopback-next/issues/5055
• StackOverflow question: Schema based Multi tenancy in Loopback 4
• StackOverflow answer: How to attach a single model (e.g. Product) to multiple datasources (LB3)
• StackOverflow anwser: How to prefix model name with tenant id (LB3)

Aspects to consider:

• CLI should recognize dynamic repository/datasource in commands like lb4 datasource
• How to boot custom artifacts - we can improve @loopback/boot (if needed) or move the registration to a different place (e.g. from a datasource file to a boot script)
• How to migrate/update database tables for all tenants when the model shape changes
• How to onboard a new tenant (create the new schema & all tables)

Start with the related LoopBack 4 issue 5055 and the linked PostgreSQL schema documentation. Review the listed concerns around CLI commands, @loopback/boot, migrations, and tenant onboarding to determine the design scope. Done would require an agreed solution, implementation improvements, documentation, and possibly an example app.