Magento2: redirection problem from observer or Logging Out from two application at same time from observer

Question

I am trying to logout from two applications

I have a logout observer, where I am trying to logout from external application and also from Magento.

Here Problem is

when I am logged out from the external application successfully, But not able to logout from Magento2 application. when I am logout from Magento2 application successfully, But not able to logout from external application

What I tried

\app\code\Mycompany\Customerhomepage\etc\frontend\events.xml

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../vendor/magento/framework/Event/etc/events.xsd">
    <event name="customer_logout">
        <observer name="mycompany_mymodule_customer_logout" instance="Mycompany\MyModule\Observer\Customerlogout"/>
    </event>
</config>

\app\code\Mycompany\MyModule\Observer\Customerlogout.php

Here below code after setRedirect, I used die();. It will logout from external application successfully not from Magento2 application.

<?php

namespace Mycompany\MyModule\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\UrlInterface;
use Magento\Framework\App\ResponseFactory;

/**
 * Class customerlogout
 * @package Mycompany\MyModule\Observer
 */
class Customerlogout implements ObserverInterface{
    protected $_responseFactory;
    protected $_url;

    /**
     * @param UrlInterface $url
     * @param ResponseFactory $responseFactory
     */
    public function __construct(
        \Magento\Framework\App\ResponseFactory $responseFactory,
        \Magento\Framework\UrlInterface $url
    ) {
        $this->_responseFactory = $responseFactory;
        $this->_url = $url;
    }
    /**
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        $customerBeforeAuthUrl = $this->_url->getUrl('http://example.com/logout.php');
        $this->_responseFactory->create()->setRedirect($customerBeforeAuthUrl)->sendResponse();
        die();

    }

2nd by changing die(); to $this. this logout from Magento2 not from external application

<?php

namespace Mycompany\MyModule\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\UrlInterface;
use Magento\Framework\App\ResponseFactory;

/**
 * Class customerlogout
 * @package Mycompany\Customerhomepage\Observer
 */
class Customerlogout implements ObserverInterface{
    protected $_responseFactory;
    protected $_url;

    /**
     * @param UrlInterface $url
     * @param ResponseFactory $responseFactory
     */
    public function __construct(
        \Magento\Framework\App\ResponseFactory $responseFactory,
        \Magento\Framework\UrlInterface $url
    ) {
        $this->_responseFactory = $responseFactory;
        $this->_url = $url;
    }
    /**
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        $customerBeforeAuthUrl = $this->_url->getUrl('http://example.com/logout.php');
        $this->_responseFactory->create()->setRedirect($customerBeforeAuthUrl)->sendResponse();
        $this;

    }

Answer 1

I am able to log out from two application from Magento and External application.

First I destroyed the Magento session and redirect to the external application from there I also deleted the session of external application. so it is logged out and I have written in such a way that after logout it redirected to Magento customer/account/logoutSuccess page. Done, Now Both applications are logout and redirect to Magento Homepage.

Vendor/MyModule/Observer/CustomerLogoutObserver.php

<?php

namespace Vendor\MyModule\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer;
use Magento\Framework\UrlInterface;
use Magento\Framework\App\ResponseInterface;
use Magento\Framework\App\Response\RedirectInterface;

 /**
     * Class customerLogout
     * @package Vendor\MyModule\Observer
     */
    class CustomerLogoutObserver implements ObserverInterface{
{
    /**
     * @param \Magento\Framework\ObjectManagerInterface $objectManager
     */
    protected $_objectManager;

    /**
     * @param  \Magento\Framework\App\ResponseFactory $responseFactory
     */
    protected $_responseFactory;


    /**
     * @param \Magento\Framework\UrlInterface $url
     */
    protected $_url;

    /*
     * @param \Magento\Framework\App\ResponseInterface $response
     */
    protected $_response;

    /**
     * @var \Magento\Framework\UrlInterface
     */
    protected $_urlInterface;


     /**
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;


    /**
     * MyObserver constructor.
     * @param \Magento\Framework\ObjectManagerInterface $objectManager
     * @param \Magento\Framework\App\ResponseFactory $responseFactory
     * @param \Magento\Framework\UrlInterface $url
     * @param \Magento\Framework\App\ResponseInterface $response
     */
    public function __construct(
        \Magento\Framework\ObjectManagerInterface $objectManager,
        \Magento\Framework\App\ResponseFactory $responseFactory
        \Magento\Framework\App\ResponseInterface $response,
        UrlInterface $urlInterface,
        RedirectInterface $redirect,
        \Psr\Log\LoggerInterface $logger,
        \Magento\Customer\Model\Session $customerSession    
    ) {
        $this->_objectManager = $objectManager;
        $this->_responseFactory = $responseFactory;
        $this->_response = $response;
        $this->_urlInterface=$urlInterface;
        $this->_redirect=$redirect;
        $this->logger = $logger;
        $this->customerSession=$customerSession;
    }

     public function execute(\Magento\Framework\Event\Observer $observer)
    {
        try {
            $customer = $observer->getEvent()->getData('customer');
            $customerGroup = $customer->getGroupId();
            $customerId= $this->customerSession->getCustomer()->getId();  
            $url = $this->_urlInterface->getUrl('http://example.com/logout.php');

             if($customerId) {
                //It will logout from Magento Application
                $this->customerSession->destroy(); 

                // And redirect to External application and logout
                $this->_responseFactory->create()->setRedirect($url)->sendResponse();

            } 

        }
    }

}

Answer 2

You have to clear from Magento cache Session variable mage-cache-sessid

<?php

namespace Mycompany\Customerhomepage\Observer;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\UrlInterface;
use Magento\Framework\App\ResponseFactory;
use Magento\Framework\App\ObjectManager;

/**
 * Class customerlogin
 * @package Mycompany\Customerhomepage\Observer
 */
class customerlogin implements ObserverInterface{
    protected $_responseFactory;
    protected $_url;
    /**
     * @var CookieMetadataFactory
     */
    private $cookieMetadataFactory;

    /**
     * @var PhpCookieManager
     */
    private $cookieMetadataManager;

    /**
     * @param UrlInterface $url
     * @param ResponseFactory $responseFactory
     */
    public function __construct(
        \Magento\Framework\App\ResponseFactory $responseFactory,
        \Magento\Framework\UrlInterface $url
    ) {
        $this->_responseFactory = $responseFactory;
        $this->_url = $url;
    }
    /**
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        $customerBeforeAuthUrl = $this->_url->getUrl('http://example.com/logout.php');
    // run this condition when coming from external application
        if ($this->getCookieManager()->getCookie('mage-cache-sessid')) {
            $metadata = $this->getCookieMetadataFactory()->createCookieMetadata();
            $metadata->setPath('/');
            $this->getCookieManager()->deleteCookie('mage-cache-sessid', $metadata);
        }
        $this->_responseFactory->create()->setRedirect($customerBeforeAuthUrl)->sendResponse();

    }
    private function getCookieManager()
    {
        if (!$this->cookieMetadataManager) {
            $this->cookieMetadataManager = ObjectManager::getInstance()->get(\Magento\Framework\Stdlib\Cookie\PhpCookieManager::class);
        }
        return $this->cookieMetadataManager;
    }


    private function getCookieMetadataFactory()
    {
        if (!$this->cookieMetadataFactory) {
            $this->cookieMetadataFactory = ObjectManager::getInstance()->get(\Magento\Framework\Stdlib\Cookie\CookieMetadataFactory::class);
        }
        return $this->cookieMetadataFactory;
    }
}