fix: Fix custom instance user migration (#7534)

backend/migrations/20260109143306_fix_custom_user_instance_2.down.sql

@@ -0,0 +1 @@
+-- Add down migration script here

backend/migrations/20260109143306_fix_custom_user_instance_2.up.sql

@@ -0,0 +1,17 @@
+DO $$
+DECLARE
+    dbname text := current_database();
+BEGIN
+    -- Revoke default privileges first
+    ALTER DEFAULT PRIVILEGES IN SCHEMA public
+        REVOKE SELECT, INSERT, UPDATE, DELETE ON TABLES FROM custom_instance_user;
+    REVOKE CREATE ON SCHEMA public FROM custom_instance_user;
+    REVOKE USAGE ON SCHEMA public FROM custom_instance_user;
+    EXECUTE format('REVOKE CREATE ON DATABASE %I FROM custom_instance_user', dbname);
+    EXECUTE format('REVOKE CONNECT ON DATABASE %I FROM custom_instance_user', dbname);
+EXCEPTION
+    WHEN others THEN
+        RAISE NOTICE 'Error in custom_instance_user migration: %', SQLERRM;
+        -- Continue without failing the migration
+END
+$$;

backend/windmill-api/src/db.rs

@@ -56,6 +56,7 @@ lazy_static::lazy_static! {
                     (20251105100125, include_str!(
                         "../../migrations/20251105100125_legacy_sql_result_flag.up.sql"
                     ).replace("✅", "")),
+                    (20260107133344, "".to_string()),
                     ].into_iter().collect();
 }