This article provides a fix for when on Adobe Commerce on cloud infrastructure you receive an error when the application accesses the var/generation directory. This might occur due to a missing constructor dependency injection. As an immediate workaround, you may turn off the symlink generation via this deployment variable:
GENERATED_CODE_SYMLINK = disabled
The build variable GENERATED_CODE_SYMLINK was removed for Adobe Commerce on cloud infrastructure 2.2 and later.
Affected versions
Adobe Commerce on cloud infrastructure 2.0.X, 2.1.X
Issue
When the Adobe Commerce application tries to access resources located in the var/generation directory, errors like the following ones might occur:
"/app/var/generation/<path/to/resource>" file could not be written Warning!file_put_contents(/app/var/generation/<path/to/resource>): failed to open stream: Read-only file system in /app/vendor/magento/<path/to/resource>
The file "/app/var/generation/<path/to/resource>" cannot be deleted Warning!unlink(/app/var/generation/<path/to/resource>): Read-only file system
Cause
The problem occurs when the constructor dependency injection has not been implemented for an optional or required dependency of the affected object. In this case, Adobe Commerce tries to generate the missing constructor dependencies on the fly, which causes an error because the var/generation directory is read-only during runtime.
Possible solution
As an immediate fix, you may change the flow of the deployment process by disabling the symlink generation using the following environment variable:
GENERATED_CODE_SYMLINK = disabled
In this case, the generated objects are being copied directly to the destination directory instead of being symlinked. Thus, Adobe Commerce can successfully generate objects on the fly.
Turning off symlink generation may increase the potential downtime of your environment during deployment.
Permissions to change variables on Development, Staging, and Production
You may set the environment variable yourself on the local and Integration (Development) environments. For Staging and Production environments, submit a support ticket requesting to change the variable.