Append ACL resource under parent custom ACL resource from another module - "Could not create an acl object: Resource id already exists in the ACL"

Question

Using two modules: Vendor_ModuleA and Vendor_ModuleB, where Vendor_ModuleA will be a backend main menu/ACL module.

Other modules (in this example Vendor_ModuleB) should use the ACL menu of Vendor_ModuleA and append a child tree entry into the navigation. The idea is that once this works, I can use resources for Vendor_ModuleC etc as well.

• ACL for ModuleA:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
    <acl>
        <resources>
            <resource id="Magento_Backend::admin">
                <resource id="Vendor_ModuleA::mainacl" title="Vendor Main ACL" sortOrder="1">
                    <resource id="Vendor_ModuleA::mainmenu" title="Vendor Module A Main Menu" sortOrder="1" />
                    <resource id="Vendor_ModuleA::systemconfigsettings" title="Vendor Module A Config Settings Access" />
                </resource>
            </resource>
        </resources>
    </acl>
</config>

• ACL for Vendor_ModuleB which I am attempting to use the resource parent tree (Vendor_ModuleA) and add a sub node inside.

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
    <acl>
        <resources>
            <resource id="Vendor_ModuleA::mainmenu">
                <resource id="Vendor_ModuleB::top_level" title="Module B Main Menu" sortOrder="1" />
            </resource>
            <resource id="Vendor_ModuleA::systemconfigsettings">
                <resource id="Vendor_ModuleB::systemconfigsettings" title="Module B Config Settings" />
            </resource>
        </resources>
    </acl>
</config>

Error

This implementation results in the following error:

Could not create an acl object: Resource id 'Vendor_ModuleA::systemconfigsettings' 
already exists in the ACL

Issue

Most resources append a sub-node into resource Magento_Backend::admin as shown in ModuleA, but when I try to do the same (append) using the node Vendor_ModuleA::systemconfigsettings it now seems to think I am updating it, which is not the intention.

Question

How do I correctly configure ACL node to append as a child in seperate module/s?

Answer 1

I managed to solve it, although unfortunately the original idea to use is now slightly more complicated than I hoped (and less maintainable if the ModuleA ACL parent nodes changes).

Solution

Use the full XML node references used in other modules, for every parent, otherwise Magento 2 currently interprets as you want to override/replace it instead of appending to ACL node

In the above example, to get Vendor_ModuleB to use the ACL nodes of Vendor_ModuleA, take the whole node structure of Vendor_ModuleA,

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
    <acl>
        <resources>
            <resource id="Magento_Backend::admin">
                <resource id="Vendor_ModuleA::mainacl">
                    <resource id="Vendor_ModuleA::mainmenu">
                        <resource id="Vendor_ModuleB::top_level" title="Module B Main Menu" sortOrder="1" />
                    </resource>
                    <resource id="Vendor_ModuleA::systemconfigsettings">
                        <resource id="Vendor_ModuleB::systemconfigsettings" title="Module B Config Settings" />
                    </resource>
                </resource>
            </resource>
        </resources>
    </acl></config>

Further explanation

The important thing to take note is that the XML is not handled the same way as in layouts.

ACL (at least in ~Magento 2.3) does not use the layout method of appending content into a referenceContainer/referenceBlock'

So, when trying with the parent node to append to : Vendor_ModuleA::systemconfigsettings I assumed the ACL will use a similar loading mechanism as layouts in Magento 2, but it does not.

All parent level nodes are required.