code: public function sendWebHook($message)
      {
          $url = $this->config->getIncomingWebhookURL();
          $messagePrefix = $this->config->getWebhookMessagePrefix();
          $currentUsername = 'System';
          try {
              if ($this->state->getAreaCode() == 'adminhtml') {
                  $getUser = $this->authSession->getUser();
                  if (!empty($getUser)) {
                      $currentUsername = $getUser->getUserName();
                  }
              }
          } catch (\Exception $e) {
              $this->log->log(100, 'Failed to retrieve Area Code');
          }
  
          $storeName = $this->helper->getStoreName();
          $storeUrl = $this->helper->getStoreUrl();
  
          $text =  $messagePrefix.' user='.$currentUsername.' '.$message.' on <'.$storeUrl.'|Store> | '.$storeName;
  
          $headers = [
              'Content-type: application/json'
          ];
  
          $body = json_encode([
              "text"  =>  $text,
              "username" => "fastly-magento-bot",
              "icon_emoji"=> ":airplane:"
          ]);
  
          $client = $this->curlFactory->create();
          $client->addOption(CURLOPT_CONNECTTIMEOUT, 2);
          $client->addOption(CURLOPT_TIMEOUT, 3);
          $client->write(\Zend_Http_Client::POST, $url, '1.1', $headers, $body);
          $response = $client->read();
          $responseCode = \Zend_Http_Response::extractCode($response);
  
          if ($responseCode != 200) {
              $this->log->log(100, 'Failed to send message to the following Webhook: '.$url);
          }
  
          $client->close();
      }
docs: Send message to Slack channel
  
  @param $message