Invalid map filename when running data migration tool from custom extension

Question

I tried to create a custom module to create a custom configuration for Magento 2 data migration tool, like this:

app/code/Vendor/Migration/etc/module.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Vendor_migration" setup_version="1.0.0">
        <sequence>
        <module name="Magento_DataMigrationTool"/>
    </sequence>
  </module>
</config>

app/code/Vendor/Migration/composer.json

{
    "name": "vendor/module-migration",
    "description": "Providing config for migration",
    "config": {
        "sort-packages": true
    },
    "require": {
        "magento/framework": "*",
        "magento/data-migration-tool": "*"
    },
    "type": "magento2-module",
    "autoload": {
        "files": [
            "registration.php"
        ],
        "psr-4": {
            "Vendor\\Migration\\": ""
        }
    },
    "version": "1.0.0"
}

app/code/Vendor/Migration/registration.php

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Vendor_Migration',
    __DIR__
);

app/code/Vendor/Migration/etc/opensource-to-opensource/1.9.3.8/config.xml

...
<options>
        <map_file>app/code/Vendor/Migration/etc/opensource-to-opensource/1.9.3.8/map.xml</map_file>
        <class_map>app/code/Vendor/Migration/etc/opensource-to-opensource/1.9.3.8/class-map.xml</class_map>
...
</options>
...

when I run the migration, I got the following error:

php bin/magento migrate:settings -r -a app/code/Vendor/Migration/etc/opensource-to-opensource/1.9.3.8/config.xml

Invalid map filename: /var/www/M2/vendor/magento/data-migration-tool/app/code/Vendor/Migration/etc/opensource-to-opensource/1.9.3.8/class-map.xml

it seems it still call the vendor module path as a prefix

Answer 1

The problem is that the rootDir in vendor/magento/data-migration-tool/src/Migration/Reader/Settings.php is set to vendor/magento/data-migration-tool/ :

$rootDir = dirname(dirname(dirname(__DIR__))) . DIRECTORY_SEPARATOR;

You can override the validate() function in your Vendor/Migration module to set the rootDir to your module's directory.