Magento cannot run with custom Composer vendor directories

[vbuck]

When using the COMPOSER_VENDOR_DIR setting to specify a vendor path outside of the Magento installation root, Magento's autoloader registration fails to generate the correct path.

Preconditions

1. Any host with access to two separate parent directories.
2. Any recent version of composer installed

Steps to reproduce

1. Create a temporary directory for vendor data: mkdir /tmp/composer-vendor-dir
2. Create a project directory: mkdir ~/magento-project
3. Set the Composer vendor directory: export COMPOSER_VENDOR_DIR="/tmp/composer-vendor-dir"
4. Create a Magento project: composer create-project --repository-url=https://repo.magento.com/ magento/project-community-edition ~/magento-project
5. Observe successful Composer installation
6. Attempt to access Magento CLI: php bin/magento

Expected result

1. Using php bin/magento should produce a command list

Actual result

1. Error message given:

Autoload error: Vendor autoload is not found. Please run 'composer install' under application root directory.

Additional Information

File app/autoload.php incorrectly assumes a vendor path relative to the project:

define('BP', dirname(__DIR__));
...
$vendorAutoload = BP . "/{$vendorDir}/autoload.php";

Which in the example scenario given produces a path like:

• /home/user/magento-project//tmp/composer-vendor-dir/autoload.php

The validation of $vendorAutoload should be modified to resolve variations of the assembled path, in a way that it can accept an absolute path returned by app/etc/vendor_path.php

[magento-engcom-team]

Hi @vbuck. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

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where {$VERSION} is version tags (starting from 2.2.0+) or develop branches (2.2-develop +).
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@vbuck do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

@vbuck, thank you for your report.
We've acknowledged the issue and added to our backlog.

[annismckenzie]

You can get around this if you at least know the relative path to the vendor dir outside of the project (e.g. you put "vendor-dir": "../composer_vendor" into your composer.json file) – I got that far but am now stuck at the problem that the template loading mechanism disallows fetching view files from a directory that's outside the Magento root. It is a security feature but the vendor directory should be exempted as it's known and might be located anywhere on the filesystem (that is, if this issue is fixed).

[vbuck]

Yes, @annismckenzie, that's right: vendor-dir is an alternative parameter; however, my main problem is that the bootstrapper itself does not have any regard for absolute paths. It always assumes relative.

You are also right about the follow-up problem, in that views cannot be fetched outside of the Magento root. I hadn't considered vendor as an exemption from that feature but it makes sense to me, in that Magento should support all variations of Composer configurations.

[magento-engcom-team]

Hi @Rus0. Thank you for working on this issue.
Looks like this issue is already verified and confirmed. But if your want to validate it one more time, please, go though the following instruction:

• 1. Add/Edit Component: XXXXX label(s) to the ticket, indicating the components it may be related to.

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  Details

  - Add the comment @magento-engcom-team give me 2.3-develop instance to deploy test instance on Magento infrastructure.
  - If the issue is reproducible on 2.3-develop branch, please, add the label Reproduced on 2.3.x.
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• 3. Verify that the issue is reproducible on 2.2-develop branch.

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• 4. If the issue is not relevant or is not reproducible any more, feel free to close it.