chore: add an example script for setting up Hasura user

db/hasura-user.sql

@@ -0,0 +1,47 @@
+-- See: https://hasura.io/docs/2.0/deployment/postgres-requirements/#2-a-single-role-to-manage-metadata-and-user-objects-in-the-same-database
+-- This only has to be done once to initialize the new user.
+-- Run this in the ferry DB.
+
+-- If you started the GQL engine with the hasura user, then you can ignore
+-- the hdb_catalog setup steps.
+CREATE SCHEMA IF NOT EXISTS hdb_catalog;
+ALTER SCHEMA hdb_catalog OWNER TO hasura;
+DO $$
+DECLARE
+   obj RECORD;
+BEGIN
+   FOR obj IN
+      SELECT format('ALTER TABLE %I.%I OWNER TO %I;', schemaname, tablename, 'hasura') AS cmd
+      FROM pg_tables WHERE schemaname = 'hdb_catalog'
+      UNION ALL
+      SELECT format('ALTER SEQUENCE %I.%I OWNER TO %I;', schemaname, sequencename, 'hasura') AS cmd
+      FROM pg_sequences WHERE schemaname = 'hdb_catalog'
+      UNION ALL
+      SELECT format('ALTER FUNCTION %I.%I(%s) OWNER TO %I;',
+                    n.nspname, p.proname,
+                    pg_get_function_identity_arguments(p.oid),
+                    'hasura') AS cmd
+      FROM pg_proc p
+      JOIN pg_namespace n ON p.pronamespace = n.oid
+      WHERE n.nspname = 'hdb_catalog';
+   LOOP
+      EXECUTE obj.cmd;
+   END LOOP;
+END $$;
+
+-- Only give read permissions to the data tables.
+GRANT SELECT ON ALL TABLES IN SCHEMA information_schema TO hasura;
+GRANT SELECT ON ALL TABLES IN SCHEMA pg_catalog TO hasura;
+
+GRANT USAGE ON SCHEMA public TO hasura;
+GRANT SELECT ON ALL TABLES IN SCHEMA public TO hasura;
+GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO hasura;
+
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO hasura;
+ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON SEQUENCES TO hasura;
+
+-- To verify that the right permissions are present:
+-- 1. Check that hasura owns the metadata tables:
+--    SELECT * from pg_catalog.pg_tables where schemaname = 'hdb_catalog';
+-- 2. Check that hasura can query the data tables:
+--    SELECT * from seasons;