Example for versioned migrations using HCL schema

1. Log in using atlas login.

2. Run atlas migrate diff --env local. Note that Atlas creates a new migration file with users and auth_users defined. However, resources defined in the baseline file/schema are not included in the diff.

-- Create "users" table
CREATE TABLE "users" ("id" uuid NOT NULL DEFAULT auth.random_user_id());
-- Create "auth_users" view
CREATE VIEW "auth_users" ("id") AS SELECT users.id
   FROM (users
     JOIN auth.users users_1 USING (id));

3. Running atlas migrate diff --env local again will not create a new migration file because the diff is empty.

Note that in the above example, migration files were generated without a schema qualifier. This is because we defined the docker.postgres.dev dev-database to operate on a single schema (public). Thus, the generated migration files can potentially be applied to any schema.

To generate migration files with a schema qualifier, we need to remove the schema argument from the docker.postgres.dev dev-database definition. The schema "public" {} block in our schema.pg.sql file controls the name of the schema that Atlas will use in migrate diff.

docker "postgres" "dev" {
  image  = "postgres:15"
- schema = "public"
  ...
}

Let's delete the migrations directory and run the atlas migrate diff --env local command again:

-- Create "users" table
CREATE TABLE "public"."users" ("id" uuid NOT NULL DEFAULT auth.random_user_id());
-- Create "auth_users" view
CREATE VIEW "public"."auth_users" ("id") AS SELECT users.id
   FROM (users
     JOIN auth.users users_1 USING (id));