README

About

The MX_PhinxMigrations module integrates Phinx database migrations into Magento 2 as a replacement for the built-in setup:upgrade method of triggering schema and data changes, therefore enabling zero-downtime deployments.

Why?

The idea of this module is to avoid having to change module versions (in module.xml files) in order to trigger database changes in Magento. When Magento bootstraps itself it verifies that all module versions in the setup_module database table match the versions on disk. If a module version in the database does not match the version in our code then Magento will error and show something like:

1 exception(s):
Exception #0 (Magento\Framework\Exception\LocalizedException): Please upgrade your database: Run "bin/magento setup:upgrade" from the Magento root directory.
The following modules are outdated:
Acme_Foo schema: current version - 0.2.0, required version - 0.3.0
Acme_Foo data: current version - 0.2.0, required version - 0.3.0

If we consider the following high level deployment process, this makes zero-downtime deployments impossible due to the fact that at some point, even if just for a very short time, the code and database versions will be out of sync between steps 2 and 3:

Build Magento container
Before deploying the new container(s), run setup:upgrade process on the target environment database
Deploy the new container(s)

Requirements

The module is currently supported on Magento >= 2.1.

Installing

Add the module to the require section of the composer file:

$ composer require mx/module-phinx-migrations

Enabling the module

$ bin/magento setup:upgrade
$ bin/magento c:c

We can verify that the module is enabled by running the status command:

$ bin/magento module:status MX_PhinxMigrations

The phinx configuration file

After installing the module you will need to create a phinx.php file in your project root folder.

An example can be found here. There should be no further changes required to this file but it can be edited as necessary for your project setup.

Using

Migrations are custom classes that extend phinx migrations and execute some code to change the DB. Migration class files can sit in any of your Magento modules (phinx will scan for all migration folders at run time) in the following locations:

src/*/*/etc/migrations
app/code/*/*/etc/migrations

Creating a migration

phinx can create a migration for us. For example

bin/phinx create AddProductPimIdAttribute

It will then ask us which module we want to add the migration file to:

Which migrations path would you like to use?
  [0] src/Foo/Catalog/etc/migrations
  [1] src/Foo/Sales/etc/migrations
 >

When the migration file is created in the selected destination we should see a class similar to the following:

<?php

use MX\PhinxMigrations\Migration;

class AddProductPimIdAttribute extends Migration
{
    /**
     * Upgrade the database.
     */
    public function up()
    {

    }

    /**
     * Rollback the database.
     */
    public function down()
    {

    }
}

When writing our migration we should always include rollback code so that we can reverse deployments easily.

Magento setup helpers

We have access to 3 different setup helpers provided by Magento in each migration:

$this->schemaSetup (instance of Magento\Framework\Setup\SchemaSetupInterface)
$this->dataSetup (instance of Magento\Framework\Setup\ModuleDataSetupInterface)
$this->eavSetup (instance of Magento\Eav\Setup\EavSetup)

Execute migrations

When you are happy with your migration you can execute it as follows

bin/phinx migrate

Rolling back

If you want to undo your migration then simply execute

bin/phinx rollback

Limitations

Upgrading Magento itself will still result in version changes in the Magento module.xml files, therefore zero-downtime deployments are not possible in this situation.

FAQ / troubleshooting

Q. When I run bin/phinx create ... it cannot find any migration paths to create the migration file, why?

A. In order for a migration to be created phinx will scan your project for migration folders in the paths mentioned in the section above. Make sure you create at least one migration folder inside one of your Magento module's etc folders and then it should work as expected.

vkovalc / module-phinx-migrations

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