graphql-engine/docs/graphql/core/migrations/upgrade-v3.rst
Rikin Kachhia 423f5c6ad5 docs: update v2 docs
- update config availablility/deprecation notes
- add notes on metadata inconsistency during config v3 migrations
- use update instead of upgrade for v2 migration for consistency
- fix external link opening

GitOrigin-RevId: a8ca31948285f55a5fac8d00b93f85007be512cc
2021-05-18 13:37:32 +00:00

248 lines
8.8 KiB
ReStructuredText

.. meta::
:description: Hasura Config V3 project
:keywords: hasura, docs, migration, metadata
.. _migrations_upgrade_v3:
Upgrading to Hasura migrations config v3
========================================
.. contents:: Table of contents
:backlinks: none
:depth: 2
:local:
What has changed?
-----------------
From ``v2.0.0`` onwards, Hasura allows us to add multiple databases to the same Hasura instance.
If we want to take advantage of multiple databases we'll have to use a ``config v3`` project
which brings some changes to the project directory when compared to ``config v2``.
``Config v3`` also brings updates to the metadata directory structure to improve version control
and collaboration workflows.To gain these benefits we recommend upgrading to ``config v3`` even
if you do not intend to use multiple databases.
Let's try to understand what these changes are.
Metadata directory
^^^^^^^^^^^^^^^^^^
The following is a sample metadata directory when using ``config v3``.
.. code-block:: bash
metadata
├── actions.graphql
├── actions.yaml
├── allow_list.yaml
├── cron_triggers.yaml
├── databases
│   ├── databases.yaml
│   └── s1
│   ├── functions
│   │   ├── functions.yaml
│   │   └── public_search_artists.yaml
│   └── tables
│   ├── public_albums.yaml
│   ├── public_artists.yaml
│   ├── public_genres.yaml
│   ├── public_media_types.yaml
│   ├── public_playlists.yaml
│   ├── public_playlist_track.yaml
│   ├── public_tracks.yaml
│   └── tables.yaml
├── query_collections.yaml
├── remote_schemas.yaml
├── rest_endpoints.yaml
└── version.yaml
Notice the introduction of a new ``databases`` directory. As the name suggests, this directory will have the
metadata related to all your databases.
Now let's looks at the contents of ``databases/databases.yaml``
.. code-block:: yaml
- name: s1
kind: postgres
configuration:
connection_info:
database_url:
from_env: DATABASE_URL
pool_settings:
idle_timeout: 180
max_connections: 50
retries: 1
tables: "!include s1/tables/tables.yaml"
functions: "!include s1/functions/functions.yaml"
We can see that we have a database called ``s1``, with it's configuration information and other metadata. Notice the peculiarity
of values of ``tables`` and ``functions`` keys. CLI now uses a special syntax to "include" contents from another file to use it
as the value for a particular key. Here it is ``!include s1/tables/tables.yaml`` , which means that CLI will try to fill in value
of ``tables`` from ``s1/tables/tables.yaml``.
Now, If we look at the contents of ``s1/tables/tables.yaml`` (as shown below) we understand that it is array whose values are again
similarly sourced from different files.
.. code-block:: yaml
- "!include public_albums.yaml"
- "!include public_artists.yaml"
- "!include public_genres.yaml"
- "!include public_media_types.yaml"
- "!include public_playlist_track.yaml"
- "!include public_playlists.yaml"
- "!include public_tracks.yaml"
Let's look at ``public_albums.yaml`` from the first line above.
.. code-block:: yaml
array_relationships:
- name: tracks
using:
foreign_key_constraint_on:
column: album_id
table:
name: tracks
schema: public
object_relationships:
- name: artist
using:
foreign_key_constraint_on: artist_id
table:
name: albums
schema: public
This file specifies the metadata related to a table called ``tracks`` in ``public`` schema. This means that each table will have it's own
file for it's metadata specifically. This makes understanding and managing metadata related to tables a lot easier.
Also note that Metadata related to functions is also managed in a similar fashion.
When doing a ``hasura metadata apply`` CLI will inline ``!include`` directives with the appropriate contents.
.. note::
Currently the CLI looks for ``!include`` directives in ``tables`` and ``functions`` keys only.
Migrations directory & Seeds directory
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
There are some changes to ``migrations`` and ``seeds`` project directories in ``config v3``. Projects will have child directories
corresponding to migrations for each connected database. Look at the following example, the ```migrations`` directory
has a sub directory ``default`` which corresponds to the connected database.
.. code-block:: bash
migrations
└── default
└── 1613987232674_init
└── up.sql
Changes needed in existing workflows
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
With the introduction of multiple databases and it's configuration being stored in metadata, it brings a change of workflow with it.
The steps to apply migrations and metadata to a new Hasura instance will be:
.. code-block:: bash
# first apply metadata, this will connect Hasura to the configured databases.
hasura metadata apply
# now we can apply migrations to the connected databases.
hasura migrate apply --all-databases
# follow it with a metadata reload to make sure Hasura is aware of any newly created database objects.
hasura metadata reload
The reason why we have to do ``metadata apply`` first instead of ``migrate apply`` (that we are used to doing in ``config v2``) is that
if we do a ``migrate apply`` first then Hasura might not yet be aware about the databases it has to connect to as that information is present
in metadata. Earlier we could not start Hasura without a connected database, but now we can.
As we are now applying metadata before migrations, your metadata might be in an **inconsistent state** after the initial ``metadata apply``
till the ``metadata reload`` step as some database objects referred to in metadata might not be available till the migrations are applied.
Also, ``hasura seeds`` and ``hasura migrate`` commands now accept a required flag ``--database-name``.
.. note::
As the database connection configuration is now picked up from metadata, it is important to ensure that all the environments
use the same env vars to store the database connection strings and the metadata being applied also uses the appropriate env
vars.
Upgrade steps
-------------
The latest version Hasura CLI comes with a convenience script used to upgrade your CLI project to use ``config v3``. Note that this process is
completely independent from your Hasura GraphQL engine server update process.
Pre update checklist / notes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1. ``Config V3`` is expected to be used with Hasura GraphQL engine versions ``v2.0.0-alpha.1`` and above.
2. During the update process CLI uses the server as the source of truth, so make sure your server is upto date.
3. The update process replaces project metadata with metadata on the server.
Step 0: Take a backup
^^^^^^^^^^^^^^^^^^^^^
Make sure you take a backup of your Hasura project before upgrading to ``config v3``.
Step 1: Upgrade to the latest CLI
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Run:
.. code-block:: bash
hasura update-cli
If you are updating to a ``beta/alpha`` release
Run:
.. code-block:: bash
hasura update-cli --version <version>
Step 2: Upgrade Hasura project to v3
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In your project directory, run:
.. code-block:: bash
hasura scripts update-project-v3
Your project directory and ``config.yaml`` should be updated to v3.
The update script will ask for the name of database the current migrations and seeds correspond to.
If you are starting Hasura with a ``HASURA_GRAPHQL_DATABASE_URL`` then the name of the database should be ``default``.
Continue using config v2
------------------------
It is possible to continue using ``config v2`` with Hasura versions ``v2.0.0`` and above if you would like to do so.
While using ``config v2`` with Hasura versions ``v2.0.0`` and above, as we have metadata and migrations for only a single database,
the server assumes that they belong to a database named ``default`` and attempts to apply them to it.
Hence, to continue using ``config v2`` we need to connect a database to Hasura GraphQL engine with the name ``default`` and then run
any metadata and migrations commands.
- If you have connected your database using the ``HASURA_GRAPHQL_DATABASE_URL`` env var, the database will be added with the name
``default`` automatically.
- Else you can connect a database with the name ``default`` following the steps :ref:`here <connect_database_v2.0>`.
Post this, the metadata and migration commands should work as usual.
.. note::
Ensure the ``version`` key in ``config.yaml`` is set to ``2`` while using ``config v2``