Migrations for an existing database and Hasura instance ======================================================= .. contents:: Table of contents :backlinks: none :depth: 1 :local: This guide is to be followed if you already have set up a database and Hasura instance and now want to start using migrations to help you track the database and GraphQL schema changes. Step 0: Disable console on Server --------------------------------- To use migrations effectively, console on the Server (which is served at ``/console``) should be disabled and all changes must go through the console served by CLI. Otherwise, changes could be made through the server-console and they will not be tracked by migrations. So, the first step is to disable console served by the GraphQL Engine server. In order to do that remove ``--enable-console`` flag from the command that starts the server or set the following environment variable to false: .. code-block:: bash HASURA_GRAPHQL_ENABLE_CONSOLE=false .. note:: If this is set in YAML, make sure you quote the word false, i.e. ``HASURA_GRAPHQL_ENABLE_CONSOLE: "false"``. Step 1: Install the Hasura CLI ------------------------------ Follow the instructions in :ref:`install_hasura_cli`. Step 2: Set up a project directory ---------------------------------- Execute the following command. For the endpoint referred here, let's say you've deployed the GraphQL engine on Heroku, then this endpoint is: ``https://my-graphql.herokuapp.com``. In case you've deployed this using Docker, the URL might be ``http://xx.xx.xx.xx:8080``. This endpoint should not contain the ``v1alpha1/graphql`` API path. It should just be the hostname and any sub-path if it is configured that way. .. code-block:: bash hasura init --directory my-project --endpoint http://my-graphql.herokuapp.com cd my-project This will create a new directory called ``my-project`` with a ``config.yaml`` file and ``migrations`` directory. This directory structure is mandatory to use Hasura migrations. You can commit this directory to version control. .. note:: In case there is an admin secret set, you can set it as an environment variable ``HASURA_GRAPHQL_ADMIN_SECRET="``. Step 3: Initialize the migrations as per your current state ----------------------------------------------------------- - Use ``pg_dump`` to export the database schema: If Postgres is running in docker, we can use the ``pg_dump`` command bundled within the ``postgres`` docker container. If you have ``pg_dump`` installed on your machine, you could use that as well. .. code-block:: bash # get the container id for postgres docker ps # dump the public schema into public-schema.sql (repeat for other schemas) docker exec pg_dump -O -x -U postgres --schema-only --schema public > public-schema.sql If Postgres is on Heroku or elsewhere, install ``pg_dump`` on your machine and use it. It comes with a standard Postgres installation which you can download and install from `here `__. .. code-block:: bash # Get the DATABASE_URL from Heroku Dashbaord -> Settings -> Reveal Config Vars # dump the public schema into public-schema.sql (repeat for other schemas) pg_dump -O -x "" --schema-only --schema public > public-schema.sql This command will create ``public-schema.sql`` which contains the SQL definitions for the public schema. - Clean up the SQL file to remove some un-necessary statements: .. code-block:: bash # POST the SQL to a serverless function and save the response curl --data-binary @public-schema.sql https://hasura-edit-pg-dump.now.sh > public-schema-edited.sql - Create a migration called ``init`` using this SQL file and the metadata that is on the server right now: .. code-block:: bash # create migration files hasura migrate create "init" --sql-from-file "public-schema-edited.sql" --metadata-from-server # note down the version # mark the migration as applied on this server hasura migrate apply --version "" --skip-execution This command will create a new "migration" under the ``migrations`` directory with the file name as ``_init.up.yaml``. This file will contain the required information to reproduce the current state of the server including the Postgres schema and Hasura metadata. The apply command will mark this migration as "applied" on the server. If you'd like to read more about the format of migration files, check out the :ref:`migration_file_format`. .. note:: Migration version cannot be "0". i.e. the files cannot be of the form ``0_.up.yaml`` Step 4: Use the console from the CLI ------------------------------------ From this point onwards, instead of using the console at ``http://my-graphql.herokuapp.com/console`` you should use the console from CLI by running: .. code-block:: bash # in project dir hasura console Step 5: Add a new table and see how a migration is added -------------------------------------------------------- As you use the Hasura console UI to make changes to your schema, migration files are automatically generated in the ``migrations/`` directory in your project. .. note:: Migrations are only created when using the console through CLI. Step 6: Apply the migrations on another instance of GraphQL engine ------------------------------------------------------------------ Apply all migrations present in the ``migrations/`` directory on a new instance at ``http://another-graphql-instance.herokuapp.com``: .. code-block:: bash # in project dir hasura migrate apply --endpoint http://another-graphql-instance.herokuapp.com In case you need an automated way of applying the migrations, take a look at the :doc:`CLI-Migrations ` docker image, which can start GraphQL Engine after automatically applying the migrations which are mounted into a directory. Step 7: Check status of migrations ---------------------------------- .. code-block:: bash # in project dir hasura migrate status This command will print out each migration version present in the ``migrations`` directory and the ones applied on the database, along with a status text. For example, .. code-block:: bash $ hasura migrate status VERSION SOURCE STATUS DATABASE STATUS 1550925483858 Present Present 1550931962927 Present Present 1550931970826 Present Present Such a migration status indicate that there are 3 migration versions in the local directory and all of them are applied on the database. If ``SOURCE STATUS`` indicates ``Not Present``, it means that the migration version is present on the server, but not on the current user's local directory. This typically happens if multiple people are collaborating on a project and one of the collaborator forgot to pull the latest changes which included the latest migration files or another collaborator forgot to push the latest migration files that were applied on the database. Syncing of the files would fix the issue. If ``DATABASE STATUS`` indicates ``Not Present``, it denotes that there are new migration versions in the local directory which are not applied on the database yet. Executing a ``migrate apply`` would take care of such scenarios.