What’s New With Kernl – December 2017

Happy December everyone! It’s been a busy month at Kernl. We’ve got a few great new features completed, some infrastructure updates, and a few bug fixes. Let’s get started.


  • Customer Management – With the release of our new License Management product we introduced the concept of “customers”. As one would expect, a customer is someone who you assign a license to. The reason we introduced this was so that you could have multiple licenses associated to a single person and easily manage those from a single place. This is a huge improvement over the previous iteration and I highly recommend that you check it out. Hop over to the “License Management’ page and then click “Manage Customers”.
  • Customer Management API – In addition to the new customer management area in the app you can now access the customer management API. There are a lot of different ways that people purchase your plugins and themes so exposing a rich API is the best way to allow integration with Kernl. If you’d like to learn more, check out the documentation.
  • Purchase Code Migration – If you are a user of the legacy “purchase code” system you can now migrate all of your existing purchase codes over to the new license management system. When you go to the license management page there is a big call-out at the top when you can migrate your purchase codes. If you do this, make sure to update your plugin_update_check or theme_update_check file and where you instantiate the Kernl update class. Documentation for using the new license management system can be found here.
  • License Domain Restrictions – You can now restrict updates that are secured by license management to specific domains.

Minor Features & Bug Fixes

  • The web app has been upgraded from Angular 1.3.x to Angular 1.6.6. This is one of the first steps in a migration path forward to the next generation of Angular and a web app UI refresh.
  • You are now able to refresh the Git repository list that Kernl has with the press of a button. Before you had to disconnect/re-connect the integration.
  • In the interest of moving quickly, the first pass of license management and customer management did not have any tests written for it. This month we added a suite of tests around both APIs so that they remain stable.
  • Our back end application servers have been upgraded to Node.js 8.9.1. This brings security updates as well as new language features.
  • The license management documentation was updated to include links to the WordPress Settings API documentation. Kernl doesn’t make any assumptions about how your plugin or theme is developed, but people often ask what the easiest way to get licenses into their app is. The WordPress Settings API is likely the easiest, so it’s now mentioned in the documentation.
  • Meta tags have been added to the marketing site so that shares to Twitter look richer.
  • There was a bug in feature flags where individually targeted flags did not toggle on/off correctly.
  • All packages on all servers have been updated with the latest security fixes.

That’s all for this month! Have a great holiday season everyone!

What’s New With Kernl – November 2017

Happy November! The last month was all heads down on one new feature: License Management.


  • WordPress License Management – As many of you know Kernl has had “Purchase Codes” for awhile now. It was clunky to use but generally very effective at it’s goal. License Management is the next generation of Kernl’s purchase code system. It’s less clunky, easier to understand, and doesn’t need to be tied to a plugin or theme. You can access it via the “License Management” button in the main menu. Pricing and usage limits can be viewed in the billing area.

What’s next?

Part of the new License Management system is the concept of customers. Ideally you should be able to tie multiple licenses to a single customer and manage them effectively through Kernl’s web interface or API. The new license management system was launched with a very simplified version of customer management, so the next month will be dedicated to making the customer management experience on Kernl amazing!

Introducing WordPress License Management with Kernl

For the past several years Kernl has been trusted with securing access to many people’s hard work via our license management system. We recently re-imagined our entire WordPress license management system, so we want to introduce it to you.

WordPress License Management

If you’ve ever sold a plugin or theme out on the open market, worrying about your plugin getting pirated is often at the top of your mind. One way to mitigate some of that risk is to use a license management solution. Kernl’s new license management system allows you to restrict access to your plugin or theme by forcing customers to activate before functionality is enabled. We can also check license codes before updates to your plugin or theme are downloaded, allowing you to restrict how many free upgrades a customer receives.

To summarize:

  • Kernl allows you to manage license keys for your product.
  • Kernl will restrict the number of updates a license is allowed to download for your product.
  • Kernl has a REST API that can allow you to restrict usage of your plugin until a license has been activated.

License Management Example

So how might you use Kernl’s WordPress license management? An example will illustrate this best.

The example above has a function to validate if a user’s license is valid. This can be used anywhere in your code to expose functionality only if the Kernl license is valid.

Restricting Update Downloads with WordPress License Management

If you would like to simply prevent your customers from downloading updates to your plugin or theme for free, just add the license parameter when you instantiate the Kernl update check class. This works the same for both plugins and themes.

The only difference between the sample above and a normal Kernl update instantiation is the inclusion of the ‘license’ property, which tells which license to try and validate with.

Going Forward

Want to give Kernl WordPress license management a try? Check out https://kernl.us and sign up. It’s free for 30 days and doesn’t require a credit card! In addition to license management and updates, we also have some great features like WordPress continuous deployment and feature flags.

What’s New With Kernl – October 2017

This month wasn’t a big feature month for Kernl, but there were some smaller bug fixes and infrastructure updates that are helping us serve our customers better. In addition to that, we also put out a short survey. Thanks to everyone who responded!

Changes & Bug Fixes

  • We are now able to automatically manage your BitBucket deploy keys. No more manually adding them!
  • Fixed & removed some flaky integration tests for feature flags.
  • Updated the documentation to reflect the BitBucket deploy key change.
  • Added some instrumentation around managing repository deploy keys and webhooks.
  • Upgraded application servers to Node.js 8.6.
  • A new cookie signature was deployed this month to fix a bug with authentication. You likely needed to re-authenticate because of it.
  • Upgraded all packages on our servers

Thats it for this month!

Private Premium Plugin Updates with Kernl.us

If you’ve ever created a plugin for WordPress and wanted to sell it you’ve likely run in to the problem of delivering updates to your customers. Agencies and internal developers run in to this problem as well.  You can’t upload your plugin to the WordPress.org repository because then it will be free for everyone, but you still really want integrated update functionality.

Kernl.us is a SaaS product that helps solve this problem (and so many others!). Kernl allows you to distribute updates to your premium plugin automatically using the built-in WordPress update functionality. So how does it work?

  1. Sign up for Kernl
  2. Create an entry for your plugin in Kernl
  3. Add 2 lines of code to your plugin.
  4. Upload your plugin to Kernl and then distribute it to your customers

Lets dive in an see how this works!

Creating a Plugin in Kernl

After you’ve signed up for Kernl, the first step to configure seamless automatic updates is to create a plugin entry in Kernl. To do so, click  the “Plugins” button in the left-hand menu.

Next, click the “Add Plugin” button.

The next step is easy. Just enter the name, slug, and description of your plugin then press “Save”.

Adding Kernl Update Code

Now that you have a plugin entry in Kernl, you can add the Kernl update code to your plugin. Download the Kernl plugin update code from https://kernl.us/static/php/plugin_update_check.php. and place it in the root directory of your plugin. Next, take note of the UUID of the plugin that you just created.

In your plugin’s main file, add the following code:

require 'plugin_update_check.php';
$MyUpdateChecker = new PluginUpdateChecker_2_0 (

Replace “MyUuidFromKernl” with the UUID of the plugin you just created.

Uploading Your Plugin to Kernl

Now that you have Kernl inside of your plugin you need to zip it up. At the folder level, go ahead and zip the plugin using the zip tool of your choice.

If you were to extract your plugin, it should look like:


If it looked like this (notice there is no nesting), Kernl will not work:


Take your plugin and click “Add Version” inside Kernl.

Next enter the version number (of the format MAJOR.MINOR.PATCH, ex 1.4.14), select the zip file you just created, and press “Save”.

Distribute Your Plugin

Now that Kernl has this version of your plugin, feel free to distribute this ZIP file to your customers. If you ever need to release an update, just make your code changes, zip them up, and upload the new version to Kernl. Within 30 seconds the update will be visible to your customers at which point they can download it!