This is a breaking change, all existing applications using compass will have to modify their contract to include a namespace. The elasticsearch index strategy has been changed, all the data will need to be re-indexed again. The user flow would be as follows:

• Client sends a request to compass for creating a new namespace. Compass will create an entry in postgres and depending on if this tenant is shared or dedicated an index and an alias will be created in elasticsearch.
• Subsequent calls to compass that relates to an asset will need to pass the namespace id.
• Client can Get/List all registered namespaces. One thing to note is, as part of the migration step, compass creates a default namespace to avoid the hassle of bootstrapping compass use-case.

Changes are made based on design discussion at #208. API changes are available in raystack/proton#246

To enforce multi-tenant restrictions at the database level, I have used Row Level Security. RLS requires Postgres users used for application database connection not to be a table owner or a superuser else all RLS are bypassed by default. That means a Postgres user that is migrating the application and a user that is used to serve the app should both be different.

To create a postgres user

CREATE USER "compass_user" WITH PASSWORD 'compass';
GRANT CONNECT ON DATABASE "compass" TO "compass_user";
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO "compass_user";
GRANT ALL ON ALL SEQUENCES IN SCHEMA public TO "compass_user";
GRANT ALL ON ALL FUNCTIONS IN SCHEMA public TO "compass_user";

ALTER DEFAULT PRIVILEGES IN SCHEMA "public" GRANT SELECT, INSERT, UPDATE, DELETE, REFERENCES
                ON TABLES TO "compass_user";
ALTER DEFAULT PRIVILEGES IN SCHEMA "public" GRANT USAGE ON SEQUENCES TO "compass_user";
ALTER DEFAULT PRIVILEGES IN SCHEMA "public" GRANT EXECUTE ON FUNCTIONS TO "compass_user";

A middware for grpc looks for x-namespace-id header to extract tenant id if not found falls back to default namespace. Same could be passed in a jwt token of Auth bearer.