graphql-engine/docs/graphql/manual/migrations/existing-project.rst
2018-10-15 14:17:21 +05:30

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Migrations for an existing project
==================================
This guide will help you if you already have set up a schema and now want
to start using migrations to help you track the database and GraphQL schema changes.
These are the steps you need to follow:
#. Install the Hasura CLI
#. Setup a project directory
#. Initialize migrations
#. For further changes, use the Hasura CLI console (``http://localhost:9695``) instead of the console served by the
GraphQL engine (E.g.: ``http://my-graphql.herokuapp.com``)
Step 0: Take a note of your GraphQL engine endpoint
---------------------------------------------------
Let's say you've deployed the GraphQL engine on Heroku, then this endpoint is: ``http://my-graphql.herokuapp.com``.
In case you've deployed this using Docker the URL might be ``http://xx.xx.xx.xx:8080``.
Step 1: Install the Hasura CLI
------------------------------
.. rst-class:: api_tabs
.. tabs::
.. tab:: Mac
In your terminal enter the following command:
.. code-block:: bash
curl -L https://cli.hasura.io/install.sh | bash
This will install the Hasura CLI in ``/usr/local/bin``. You might have to provide
your ``sudo`` password depending on the permissions of your ``/usr/local/bin`` location.
.. tab:: Linux
Open your linux shell and run the following command:
.. code-block:: bash
curl -L https://cli.hasura.io/install.sh | bash
This will install the Hasura CLI tool in ``/usr/local/bin``. You might have to provide
your ``sudo`` password depending on the permissions of your ``/usr/local/bin`` location.
.. tab:: Windows
.. note::
You should have ``git bash`` installed to use Hasura CLI. Download ``git bash`` using this `link
<https://git-scm.com/download/win>`_. Also, make sure you install it in ``MinTTY`` mode, instead of Windows'
default console.
Download the ``hasura`` installer:
* `hasura (64-bit Windows installer) <https://cli.hasura.io/install/windows-amd64>`_
* `hasura (32-bit Windows installer) <https://cli.hasura.io/install/windows-386>`_
**Note:** Please run the installer as ``Administrator`` to avoid PATH update errors. If you're still
getting a "command not found" error after installing Hasura CLI, please restart ``git bash``.
Step 2: Setup a project directory
---------------------------------
Skip this step if you already have a project directory.
.. code-block:: bash
hasura init --directory my-project --endpoint http://my-graphql.herokuapp.com
Step 3: Initialize the migrations as per your current state
-----------------------------------------------------------
- Install ``pg_dump`` (or use Docker) and run the following command to download the public schema as ``public-schema.sql``:
.. code-block:: bash
pg_dump -O -x -h <db-host> -p <db-port> -U <db-user> -d <db-name> --schema public --schema-only > public-schema.sql
- Export the metadata (this creates a file ``metadata.yaml``):
.. code-block:: bash
hasura metadata export
- Create a new migration with a name, say ``first``. This will generate some files in ``migrations/`` directory:
.. code-block:: bash
hasura migrate create first
- Move the contents of ``public-schema.sql`` to ``migrations/<version>_first.up.sql``
- Move the contents of ``metadata.yaml`` to ``migrations/<version>_first.up.yaml`` with the following content
(take care of indentation):
.. code-block:: yaml
- type: replace_metadata
args:
<contents-of-metadata.yaml>
- Remove ``migrations/<version>_first.down.{sql,yaml}`` migration files if you are not adding down migrations for these
Step 4: Use the console from the CLI
------------------------------------
Instead of using the console at ``http://my-grapqhl.herokuapp.com/console`` you should now use the console by running:
.. code-block:: bash
# Without access key
hasura console
# With access key
hasura console --access-key mysecretkey
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 to another instance of the GraphQL engine
----------------------------------------------------------------------
- Edit ``config.yaml`` and change the endpoint to another instance, say ``https://my-another-grapqhl.herokuapp.com``:
.. code-block:: yaml
# config.yaml
endpoint: https://my-another-grapqhl.herokuapp.com
- Apply all migrations present in the ``migrations/`` directory on this new instance:
.. code-block:: bash
hasura migrate apply
Step 7: Create migrations without the console & other advanced actions
----------------------------------------------------------------------
- Each migration consists of a pair of yaml and sql files with up and down steps.
- Create migrations manually using :ref:`migrate create <hasura_migrate_create>`.
- You can apply only certain versions or numbers of steps. Read more at :ref:`migrate apply <hasura_migrate_apply>`