Customer Logout Observer in Magento2?

Question

How can I set an event observer for customer logout action in magento2?

Answer 1

you can observe one of the events controller_action_predispatch_customer_account_logout or controller_action_postdispatch_customer_account_logout depending on when you want to observe things. before loging out or after.

or you can observe the customer_logout event for the exact logout moment.

To write an observer you need to create in your module the file etc/frontend/events.xml with this content:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="{event_name_here}"> <!-- use one of the events above -->
        <observer name="[namespace]_[module]" instance="[Namespace]\[Module]\Observer\Logout" />
    </event>
</config>

then create the file [Namespace]/[Module]/Observer/Logout.php

<?php 
namespace [Namespace]\[Module]\Observer;

class Logout implements \Magento\Framework\Event\ObserverInterface 
{
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        //your code here
    }
}

Answer 2

The event name is customer_logout

In your custom module create app/code/{Company}/{Module}/etc/frontend/events.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="customer_logout">
        <observer name="{company_module}_customer_logout" instance="{Company}\{Module}\Observer\Frontend\CustomerLogOutObserver" />
    </event>
</config>

Then create your observer in {Company}{Module}\Observer\Frontend\CustomerLogOutObserver.php

namespace {Company}\{Module}\Observer\Frontend;
use Magento\Framework\Event\Observer as EventObserver;
use Magento\Framework\Event\ObserverInterface;

class CustomerLogOutObserver implements ObserverInterface
{

    public function execute(EventObserver $observer)
    {
        //do stuff here
    }
}

Take a look at app/code/Magento/Customer/Controller/Account/Logout.php

/**
 * Customer logout action
 *
 * @return \Magento\Framework\Controller\Result\Redirect
 */
public function execute()
{
    $lastCustomerId = $this->session->getId();
    $this->session->logout()->setBeforeAuthUrl($this->_redirect->getRefererUrl())
        ->setLastCustomerId($lastCustomerId);
 ....

Then app/code/Magento/Customer/Model/Session.php

/**
 * Logout customer
 *
 * @api
 * @return $this
 */
public function logout()
{
    if ($this->isLoggedIn()) {
        $this->_eventManager->dispatch('customer_logout', ['customer' => $this->getCustomer()]);
        $this->_logout();
....