Awesome

Magento 2 Breadcrumbs

Magento 2 (as Magento 1) has a lot of pages where breadcrumbs are missing.
some of them might not need them, but for others I think they might be needed.
Specially for the customer account pages.
Having breadcrumbs will improve the customer experience and will make the navigation easier.

This is based on the no-longer maintained https://github.com/tzyganu/m2-breadcrumbs

Installation

composer require imi/m2-breadcrumbs

You can find a list of supported pages in etc/frontend/breadcrumbs.xml.
If you don't want breadcrumbs for a specific page then you can manage the pages from Stores->Configuration->Easylife Breadcrumbs.

Extending

If you have other pages that you thing need breadcrumbs, create a module that depends on this one and add a file etc/frontedn/breadcrumbs.xml validated by the same xsd file Easylife/Breadcrumbs/etc/frontend/breadcrumbs_file.xsd where you can list your pages.
You can add a new page by adding this in your config file:

<page id="page_layout_handle" group="group_code"><!-- available groups are listed also in breadcrumbs.xml -->
    <label>Store configuration label  here</label>
    <methods>
        <method name="methodNameHere" sort="10" class="Class\Name\Here" /><!-- this will call the method Class\Name\Here::methodNameHere on the event controller_action_layout_render_before_page_layout_handle -->
       <method name="otherMethodNameHere" sort="20" class="Class\Name\Here" /><!-- this will call the method Class\Name\Here::otherMethodNameHere on the event controller_action_layout_render_before_page_layout_handle -->
    </methods>
</page>

If the class attribute is missing it will call the method from the Easylife\Breadcrumbs\Model\Observer class.

Educational

You can use this module for learning purposes. Is shows you how to create a config loader (I hope I've done it right).
It also shows you how to use di.xml. The observer for all events is Easylife\Breadcrumbs\Model\Observer\ObserverInterface and the di.xml file contains a preference for this interface.
<preference for="Easylife\Breadcrumbs\Model\Observer\ObserverInterface" type="Easylife\Breadcrumbs\Model\Observer" />