Skyhook Generic Processor

Introduction and Overview

This TechNote covers how to deploy and configure the ClearPass ‘Skyhook Generic Processor’ Extension that provides a simple method for customers to push data from a cloud app to an on-prem ClearPass using a webhook style interface. For example, a use-case workflow may require a cloud enabled app to create Guest accounts, Devices or Endpoints within the ClearPass Guest framework.

You may think of it as optimizing several existing manual actions within an existing Help/Service Desk workflow that authorizes Guest accounts, Devices or Endpoints and then the operator has to access the ClearPass Guest Portal to manually create the Guest account, Device or Endpoint. Using this Extension, the workflow can now be simplified by automatically triggering the creation of a Guest account, Device or Endpoint by sending data in a webhook directly from the cloud app. This eliminates the requirement to login to the ClearPass Guest Portal to manually create the account, device or endpoint.

A real world example for this may be taking the input from a Cloud-based Ticketing system workflow and automatically creating the Guest account right from the cloud app, eliminating the second manual step for the Help/Service Desk to login and create the account within ClearPass – for example, ServiceNow or any other cloud app that can send data in a webhook.

The idea here is that this Integration opens up the possibilities of creativity to link cloud-apps with ClearPass as any attributes that are part of the (Guest, Device and Endpoint) REST API can be leveraged.

With apps hosted in the cloud and ClearPass sitting primarily on-prem, there are challenges in making these two applications communicate in real time so the desired output from the cloud app triggers an action and response within ClearPass. Traditionally the apps would communicate using APIs where an application would request information which is usually followed by a response. In order to get real-time information, the app would have to continuously poll or request the data, however that would not be a scalable solution. The solution for this is to use a webhook as it does not wait for a request to send information but rather sends the data as soon as it’s available.

Before we proceed with the flow, we need to understand the concepts of webhooks and Skyhook.

What is a webhook?

A webhook (also called a web callback or HTTP push API) is a way for an app to provide other applications with real-time information. A webhook delivers data to other applications as it happens, meaning you get data immediately.

What is Skyhook?

Skyhook was developed to overcome the inability for cloud-based applications to send events [webhooks] directly into a ClearPass system that is typically deployed on the trust side of a corporate firewall. In short, it is a service that runs in the Cloud, developed and managed by HPE Aruba Networking. ClearPass nodes running on-prem, use Extensions to open a persistent connection into Skyhook to receive the events originally sent from a 3rd party cloud application specific for that customer/tenant.

The cloud-based app will send a webhook to trigger a Guest, Device or Endpoint event and it will be consumed by Skyhook. The installed ClearPass ‘Skyhook Generic Processor’ Extension will maintain a persistent connection with Skyhook and process the cloud apps events in real-time.

Software Requirements

The minimum software version required for CPPM is 6.11.0 . At the time of writing, version 6.11.10 is available as the long supported release and 6.12.4 is available as the short supported release. CPPM runs on hardware appliances with pre-installed software or as a Virtual Machine under the following hypervisors. Hypervisors that run on a client computer such as VMware Player are not supported.

• VMware vSphere Hypervisor (ESXi) 7.0 U3c and 8.0

• Windows Server 2019 with Hyper‑V and Windows Server 2022 with Hyper‑V.

• KVM on CentOS Stream 8, CentOS Stream 9, Ubuntu 20.04 LTS, and Ubuntu 22.04 LTS.

ClearPass Installation and Deployment Guide

This document assumes your ClearPass environment is already configured and operational. If you require assistance with basic deployment, refer to the following deployment guide:

https://arubanetworking.hpe.com/techdocs/ClearPass/6.11/Installation-Guide/Default.htm

ClearPass Extensions

The integration between ClearPass Policy Manager and external systems is driven through a ClearPass capability known as Extensions, a sub-component of the ClearPass Exchange Integration framework. ClearPass Extensions are micro-services running on top of the base ClearPass platform. These micro-services enable HPE Aruba Networking to deliver new features outside of the main software release cycle and facilitate a faster time to market for specific features and integrations. Configuration and control of ClearPass Extensions is accomplished through the ClearPass Guest GUI, as covered later in this document.

Installing Extension

ClearPass Extensions are easy to install from the ClearPass Extensions Store. In a cluster, ClearPass Extensions can be installed on a subscriber independently of the publisher. Multiple copies of the same extension can be installed if needed as well.

Access to the extension store

Access the Extension Store to download and install ClearPass extensions. The Extension store utilizes the same HPE Passport account credentials used to validate support entitlement in the Software Updates Por- tal. This is configured under Administration > Agents and Software Updates > Software Updates as shown below. Ensure that valid HPE Passport credentials have been entered in these fields to enable Ex- tension download capabilities.

Installing the Extension from Store

Extensions are installed from the extension page in ClearPass Guest, as shown below. Access it from Guest > Administration > Extensions

From here, click on ‘Install Extension’, and the search box below appears.

Enter “Intune” and click on ‘Search’, see the example below.

Click on the extension name and then click “Install.”

In the “Install Extension” dialog box, set the IP address if necessary, as described in section “Extensions and IP address configuration support” below. Do not check the box to start the extension at this time. Click the “Install” button.

In this example, we’ve not entered an IP address for the extension to use, if there is intent to use the extension as an authorization source set this value and ensure its set the same on all nodes where the Extension is deployed.

The extension will download and appear in a “Stopped” state. Notice the options to Start, Delete, Reinstall, Show Logs, and view Configuration. Click on “Configuration” to view settings.

After the extension has been installed, proceed to configure the extension

A copy of the default Extension configuration is shown above, this will need to be modified for your deployment.

Extensions and web proxy support

Extensions support communications with 3^rd parties via a web proxy. This adds incremental proxy functionality. If a proxy is defined in ClearPass Policy Manager, then an extension will inherit that configuration. See later in the document on how to disable the proxy inherited configuration.

Extensions and IP address configuration support

ClearPass uses a non-externally routed IP address range to communicate with the Extension. The default is 172.17.0.0/16. You may configure a different range, if desired. This is especially useful when deploying extensions across nodes within a cluster where there is the requirement for a fixed consistent IP address for the extension across the cluster.

Changing the “Extensions Network Address” range is only necessary if either the ClearPass MGMT or DATA interface are using an IP address in the extension default range of 172.17.x.x/12, or if ClearPass needs to communicate with some external device in that range.

To Configure the base Extension IP subnet within Policy Manager navigate to Administration > Server Manager > Server Configuration [chose your node] Service Parameters [ClearPass system service].

Pictorial View of the Integration

The diagram below shows a pictorial overview of the components and how they interact with each other.

Configuration Steps

The following steps are required to get this integration working:

1. Register and request a Skyhook Tenant ID

2. Install and configure the Skyhook Generic Processor Extension

Step 1: Register and Request for a Skyhook Tenant ID

Skyhook Tenant ID’s can be registered in the skyhook self-service portal by accessing the following link https://clearpass.arubanetworks.com/webhooks/skyhook and instructions on using the skyhook self-service portal is available here: https://arubanetworking.hpe.com/techdocs/NAC/clearpass/integrations/clearpass-extension/skyhook-self-service-portal/

• Copy the skyhookTenant and the dbAccessToken to a text file. This will be used for configuration of the extension in ClearPass.

Skyhook Generic Processor Extension Configuration

The ClearPass Skyhook Generic Processor Extension communicates with your Skyhook tenant via REST API calls. The extension establishes and maintains a persistent connection to Skyhook where it continuously ingests data received into Skyhook from your cloud-enabled application. The extension configuration and supported data types are shown below.

For your convenience, a copy of the default Extension configuration.

Default Configuration

{

"logLevel": "INFO",

"verifySSLCerts": true,

"dbAccessToken": "********",

"skyhookTenant": "",

"useHeaderPreSharedKey": false,

"headerPreSharedKeyName": "X-Skyhook-PSK",

"headerPreSharedKeyValue": "",

"guestRandomPasswordLength": 5,

"guestDefaultRoleId": 2,

"guestSendRegistrationSms": false,

"guestSendRegistrationEmail": false,

"guestDefaultAccountExpireHrs": 2,

"deviceDefaultRoleId": 2,

"deviceDefaultAccountExpireHrs": 2,

"enableStats": false

}

ClearPass Skyhook Generic Processor Extension Configuration

After installing the Extension, the default configuration will need to be updated.

At a minimum, the “dbAccessToken” and “skyhookTenant” need to be changed with values received in your registration email.

Below is an explanation of all of the configuration value pairs. The logLevel and verifySSLCerts should be left as their default settings unless advised by ClearPass TAC or your SE/Partner. Once you configure these parameters, you can start your extension. Any subsequent reconfiguration requires a restart of the extension.

Table 1: Skyhook Processor Extension-specific configuration parameters

Supported Skyhook Datatypes

For each data type there are 3 possible actions, "update", "replace", or "delete".

Action Details

Data Types

Guests

{
  "action": "update",
  "guest": {
    "username": "Guest.User@hpe.com",
    "email": "Guest.User@hpe.com",
    "expire_time": 1596240000,
    "enabled": true,
    "visitor_company": "",
    "visitor_name": "",
    "visitor_phone": ""
  }
}
        

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{tenantId}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'X-Skyhook-PSK: {PSK Value}' \
--data-raw '{
  "action": "update",
  "guest": {
    "username": "Guest.User@hpe.com",
    "email": "Guest.User@hpe.com",
    "expire_time": 1596240000,
    "enabled": true,
    "visitor_company": "",
    "visitor_name": "",
    "visitor_phone": ""
  }
}'
        

Devices

{
  "action": "update",
  "device": {
    "mac": "01-02-03-04-05-06",
    "email": "Guest.User@hpe.com",
    "expire_time": 158708348,
    "enabled": true,
    "visitor_company": "",
    "visitor_name": "",
    "visitor_phone": ""
  }
}
        

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{tenantId}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'X-Skyhook-PSK: {PSK Value}' \
--data-raw '{
  "action": "update",
  "device": {
    "mac": "01-02-03-04-05-06",
    "email": "Guest.User@hpe.com",
    "expire_time": 158708348,
    "enabled": true,
    "visitor_company": "",
    "visitor_name": "",
    "visitor_phone": ""
  }
}'
        

Endpoints

{
  "action": "update",
  "endpoint": {
    "mac_address": "01-02-03-04-05-06",
    "status": "Known or Unknown",
    "attributes": {
      "Source": "",
      "My Custom Attribute": "Attribute Value"
    }
  }
}
        

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{tenantId}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'X-Skyhook-PSK: {PSK Value}' \
--data-raw '{
  "action": "update",
  "endpoint": {
    "mac_address": "01-02-03-04-05-06",
    "status": "Known or Unknown",
    "attributes": {
      "Source": "",
      "My Custom Attribute": "Attribute Value"
    }
  }
}'
        

How to test the Integration using cURL

This Tech Note was written to illustrate how a Generic cloud-based application could create or manipulate Guest accounts, Devices or Endpoints. Most apps would provide the capability to send or POST data in a webhook json payload and within this guide we use cURL to send the data.

The following example uses a widely deployed command line tool found in many operating systems call cURL. More details on the cURL client can be found on the following website http://curl.haxx.se/

The following three use-cases will demonstrate how you can update, replace or delete Guest accounts, Devices and Endpoints.

Creating a Guest Account

For your convenience, copy the following text to paste into your terminal or into Git Bash terminal in Windows.

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{Insert-your-tenantId}' \ --header 'Accept: application/json' \

--header 'Content-Type: application/json' \

--header 'X-Skyhook-PSK: {PSK Value}' \

--data-raw '{

"action": "update",

"guest": {

"username": "guest.user@hpe.com",

"email": "guest.user@hpe.com",

"expire_time": 1596240000,

"enabled": true,

"visitor_company": "HPE Aruba Networking",

"visitor_name": "Guest User",

"visitor_phone": "5556789"

}

}'

Verifying the Cloud-based Applications creation of Guest Accounts

To examine the result of the webhook sent by your cloud-app, go to ClearPass Guest and navigate to ‘Guest’ ** ‘Manage Accounts’ and you will see the account was created. Verify by clicking on “Show Details” as shown below.

Creating a MAC Device

For your convenience, copy the following text to paste into your terminal or into Git Bash terminal in Windows.

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{Insert-your-tenantId}' \ --header 'Accept: application/json' \

--header 'Content-Type: application/json' \

--header 'X-Skyhook-PSK: {}' \

--data-raw '{

"action": "update",

"device": {

"mac": "F4-2E-7F-C6-56-0C",

"sponsor_name": "admin",

"expire_time": 0,

"enabled": true,

"visitor_company": "HPE Aruba Networking",

"visitor_name": "AP515 - CSE Lab"

}

}'

Verifying the Cloud-based Applications creation of a MAC Device

To examine the result of the webhook sent by your cloud-app, go to ClearPass Guest and navigate to ‘Devices’ ** ‘Manage Devices’ and you will see that it was created. Verify by clicking on “Show Details” as shown below.

Creating an Endpoint

For your convenience, copy the following text to paste into your terminal or into Git Bash terminal in Windows.

curl --location --request POST 'https://skyhook.clearpassbeta.com/api/skyhook/processor/{Insert-your-tenantId}' \ --header 'Accept: application/json' \

--header 'Content-Type: application/json' \

--header 'X-Skyhook-PSK: {}' \

--data-raw '{

"action": "update",

"endpoint": {

"mac_address": "01-02-03-04-05-06",

"status": "Known",

"attributes": {

"Source": "Scotts-Cloud-App-Testing",

"My Custom Attribute":"MyCustomAttributeValue"

}

}

}'

Verifying the Cloud-based Applications creation of an Endpoint

To examine the result of the webhook sent by your cloud-app, go to ClearPass Policy Manager and navigate to ‘Configuration’ ** ‘Identity’ ** ‘Endpoints’ and you will see that it was created – you can find it quickly with the MAC Address Filter. Verify by clicking on the “MAC Address” to see the general Endpoint status and ‘Attributes’ as shown below.

Appendix A – Troubleshooting and Support

Here we list some basic troubleshooting steps. If you need any help beyond this, please reach out to HPE Aruba Networking Support.

Check API Access Application Control restrictions

If you’ve previously hardened your ClearPass deployment with Application Access Controls, it’s possible that the Extension will not work. Reviewing the Extension Log might show something like the following after immediately starting the Extension. This likely indicates the ClearPass Application API’s are in place.

Example of Extension authorization failure due to Policy Manager Application Control:

[2020-03-16T15:42:21.083] [INFO] Intune - Server listening on port 80.

[2020-03-16T15:42:21.243] [DEBUG] Intune - Request “GET ‘https://172.17.0.1/api/server/version’” took 51.91ms.

[2020-03-16T15:42:21.245] [DEBUG] Intune - <!DOCTYPE html><html>

<head>

<title>

Error 403 (Forbidden)

</title>

<script language=“javascript”>

function reloadPage() {

var locHref = window.location.protocol + “//” + window.location.hostname;

window.location.href = locHref;

}

</script>

To resolve this issue, add the IP address of the Extension to the list of nodes permitted to access the API by navigating to Administration > Server Manager > Server Configuration {choose your node} > Network

Checking on the Extension Service

The ClearPass Extensions are supported by a system service which must be running.

Restarting this service will affect all deployed and running extensions.

To check on the state of the Extension Service, or to restart the service, go to Administration > Server Manager > Server Configuration > [SERVER] > Service Control. By default this service is automatically started.

Extensions and web proxy / firewall whitelisting

If ClearPass Policy Manager has been configured with a proxy, it’s still possible that domain whitelists are required, the same for some datacenter firewall to allow the installation of Extensions. Some enterprise customers maintain a whitelist of domain that are allowed to transit the proxy/firewall. The underlying docker configuration process uses standard docker registry access to pull images (hosted in docker hub). In general, the following hosts are used:

This is all also geo dependent to some degree and based on various AWS services, so AWS redirects and geo location services will vary. Finally, this all runs via standard HTTPS (port 443).

Extension Logs/Enable Debugging

If you have a requirement to access and view the logs from the Extension, you can turn on different logging levels from the Extension GUI. Adjust the logLevel to ‘DEBUG’ and restart the extension as shown below.

Logs can then be viewed from the ‘Show Logs’.

Remember after changing the logging level, as with any extension configuration change the extension will need to be restarted for this change to take effect.

Accessing the extension logs using ‘Collect Logs’ system function

In addition to viewing the logs as shown above, logs can also be collected and examined via the Policy Manager Collect Logs system function (Administration > Server Manager > Server Configuration > [Select SERVER] > Collect Logs). This is extremely useful should you have a need to call for technical assistance.

If the support team needs to investigate a system issue, one of the items they regularly ask for is the system logs to aid with their diagnostic investigation. By default the “logLevel” is set to INFO, but TRACE, DEBUG, INFO, WARN, ERROR, FATAL can also be set as required. Any of the levels will display the information for the selected state and lower; if INFO is selected, it will show messages for INFO, WARN, ERROR, FATAL.

After the logs have been collected, downloaded and expanded, you can locate the extension logs in the following location in the folder structure PolicyManagerLogs > extension > your-extension-id as shown below. Note the file-name is the same as the running instance ID of the extension.

Monitoring extension statistics

There is a way to monitor extension’s critical resource statistics with the configurable parameter added as part of the extension’s configuration. To enable extension statistics set the “enableStats” parameter to true. Remember a restart of the extension is need to activate the change anytime the config is modified.

To navigate to statistics page, click Show Details.

This will show statistics similar to the following:

Monitoring authorization performance

Since we are authorizing against an external system, it could be relevant to monitor the performance of these transactions as you setup and deploy. If you suspect there is a performance issue, ClearPass provides a way to monitor the authorization processing time. The graph below shows an example of this data, navigate to Monitoring > Live Monitor > System Monitor [click on ClearPass Tab, then select [Authorization]….

Appendix B – Considerations for Installing in a Cluster

Extensions are not synced between ClearPass cluster members, and thus must be installed on each member separately.

Some Extensions can run in two modes: Periodic Sync Mode and Authorization Source Mode.

Periodic Sync Mode

If you are configuring the extension to poll external system periodically and utilize the resulting ClearPass Endpoint database during endpoint Authorization, then you only need to install the extension on one cluster member, often the publisher.

You may wish to install the extension on a second cluster member as a backup, but remember that both extensions will individually be updating the endpoint database. You may want to stagger the updates between the two extensions, for example, Subscriber1 updates at the top of the hour and Subscriber2 updates at 30 minutes after the hour.

Also, in this mode there is no need to explicitly enter an IP address during installation. The defaults will suffice and ClearPass will select an IP in the range specified in the server configuration.

HTTP Authorization Source Mode

In this mode we configure an HTTP Auth source that results in a HTTPS call to external system during endpoint authorization. In this deployment model the extension must be installed on every cluster node that process authentications. Also in this scenario every cluster member’s extension must be set to the exact same IP address during installation time, as the HTTP Auth source configuration is propagated globally across all cluster members.

For example, if the extension IP range is 172.17.0.0/16, we would set the extension to 172.17.0.5 on every cluster member during installation of the extension.

While we normally want to avoid duplicate IP addresses in a network, this is not a concern with ClearPass extensions. Each ClearPass node communicates internally only with its own extension, and this traffic is not routed outside of ClearPass.

Subscriber nodes support the same ability as publishers to install an Extension from the Extension store.

Appendix C – endpoint sync schedule settings

The syncSchedule and similar scheduling parameters sets how often ClearPass executes certain actions like syncing or pushing endpoints. This setting is based on a slightly modified version of the CRON job scheduler found in Unix-like operating systems. It can be used to schedule jobs to run periodically at fixed times, dates or intervals.

A ‘cron’ is a job scheduler. Any scheduled task is called a ‘cron job’. The syntax for a cron job schedule is as follows:

In our use of the cron scheduler, we’ve dropped the use of the last instruction ≤command to execute> and use only the time/date functions, see below for a number of examples of scheduling a sync process.

• Schedule a sync to run at 2am daily:- 0 2 * * *

• Schedule a sync to run twice a day at 5am and 5pm:- 0 5,17 * * *

• Schedule a sync to run on every Sunday at 5pm:- 0 17 * * sun

• Schedule a sync to run every 30 minutes:- */30 * * * *

• Schedule a sync to run at 5pm on selected days:- 0 17 * * sun,fri

You can see from the above that the scheduling process is extremely flexible, alternatively https://crontab.guru/ is a great page for learning more about CRON scheduling.

Appendix D – Extension performance optimizations

Extensions are a critical part of ClearPass deployments today and with the increased dependency on extension interactions that involve periodic polling or real-time lookups, here are some of the best practice recommendations around optimizing overall performance when using extensions:

• If the extension is used to periodically poll external systems and populate endpoint repository, ensure that it is not installed in all the nodes in the cluster. Ideally these type of extensions should only be installed on the publisher node since only publisher node can add endpoint entries to the database. For redundancy, it can be installed on another additional node but it is recommended to stagger the polling interval so that both do not attempt to poll and update endpoint database at the same time.

  Example: 0 * * * *, This cron job runs at minute 0 of every hour (e.g., 00:00, 01:00, 02:00, etc.).

    30 * * * *, This cron job runs at minute 30 of every hour (e.g., 00:30, 01:30, 02:30, etc.).
  

• If the extension is used for looking up attributes from external systems in real time during authentication, it should be installed in all the nodes handling authentication. Note that the context server config is replicated from the publisher. When using extension for real time lookup, ensure that the extension has the same IP address in all the cluster nodes.

• If the extension is expected to do both real-time lookup and periodic polling, ensure that polling is enabled only on the publisher while the extension in subscribers can have the polling disabled by setting the “enableSyncAll” attribute to false.

     "enableSyncAll": false,
  

• Some 3rd party systems support fetching delta updates vs fetching all of the device information every polling cycle. The extensions that support fetching delta updates are: Workspace ONE Crowdstrike Falcon Microsoft Intune Mosyle SentinelOne Service Now

  For these extensions, the syncUpdatedOnly attribute should be set to true in extension config so that the number of DB updates in ClearPass is minimized

    "syncUpdatedOnly": true,
  

  For extensions that do not support syncUpdatedOnly, ensure that the sync interval is not aggressive. We recommend syncing at most twice a day and that too during off peak hours whenever a full sync is performed.

• Some 3rd party systems can be very noisy in terms of attribute updates. There could be certain attributes that keep changing every sync interval like “Free Memory in Bytes”, “Last Check in Time” etc. There is no value in updating endpoints when such trivial attributes change for the device. Hence it is recommended to use “ignoreEndpointDifferences” attribute in extension configuration to ignore change in attributes that you do not care about in terms of ClearPass policies.

  You can review the Audit Viewer in ClearPass under Monitoring > Audit Viewer to see what attributes are being updated for endpoints to check if there are unnecessary updates.

  Sample for JAMF extension:

    "ignoreEndpointDifferences": "Last Update, Report Date UTC, Last Contact Time UTC, Last Inventory Update UTC, Last Reported IP, IP Address",
  

  Default for Microsoft Intune extension:

    "ignoreEndpointDifferences": "Last Sync Date Time, Free Storage Space in Bytes",
  

• To further optimize the number of endpoints being updated in ClearPass, you can specify which attributes are being used in the ClearPass policies so that only changes to those attributes would trigger an update to the endpoint. This is done by listing out the specific attributes under endpointAttributes in extension configuration.

  Sample for JAMF extension:

    "endpointAttributes": "Group names, MDM Enabled, Managed, Remote Managed, Supervised, Serial Number",
  

• Setup extension to restart unless it was intentionally stopped. A restart policy can be defined in extension configuration to ensure that the extension starts up automatically after server reboots and such. Restart policy of “unless-stopped” would ensure the extension always starts up unless it was manually stopped.

  “restartPolicy”: “no” — The extension will not be automatically restarted after the server is restarted.

  “restartPolicy”: “always” — The extension will always be restarted after the server is restarted.

  “restartPolicy”: “unless-stopped” — The extension will be restarted unless it was stopped prior to the server restart, in which case it will maintain that state.

  “restartPolicy”: “on-failure:N” — If the extension fails to restart, the value for “N” specifies the number of times the extension should try to restart. If you do not provide a value for “N”, the default value will be “0”.

  The “restartPolicy” parameter is not present by default in extension configurations. When it is not present, if the system is restarted a default policy is applied to the extension to maintain the state it was in before the restart. If the “restartPolicy” parameter is added to the configuration but later removed, the extension will then revert to the default restart policy.