Automatic Updates For Private And Commercial Plugins

Last updated on June 26, 2015.

Since time immemorial, only plugins hosted in the official WordPress.org plugin directory have supported automatic updates. Now, I’ve written a PHP library that you can use to add automatic update capabilities to any plugin. Public, private and commercial plugins alike – all can now enjoy the benefits of automatic update notifications and one-click upgrades.

The custom update checker integrates closely with the upgrade system already built into WordPress, producing a seamless user experience. Observe :

An upgrade notice for a privately hosted plugin.

An upgrade notice for a privately hosted plugin.

The version information window with placeholder data

The version information window with placeholder data

Download

License

This library is released under the MIT License and is distributed free of charge. If you find it useful, consider making a donation.

Quick-start Guide

This section describes the quickest way to get automatic updates working for your plugin. Here’s what you’ll need to do: create a metadata file for your plugin, host it somewhere publicly accessible, and tell the update checker where to find it.

Lets start with the metadata. Copy the JSON code below into a new file and replace the placeholder values with your plugin’s info.

{
    "name" : "My Cool Plugin",
    "slug" : "my-cool-plugin",
    "download_url" : "https://example.com/plugins/my-cool-plugin.zip",
    "version" : "2.0",
    "author" : "John Smith",
    "sections" : {
        "description" : "Plugin description here. Basic HTML allowed."
    }
}

(This is the minimum amount of data required to make automatic updates work. In most cases, you will probably want to add a couple more fields. See the metadata docs for a full list.)

Most of the fields should be pretty self-explanatory, with one possible exception – the “slug”. WordPress expects all plugins that support automatic updates to have a unique textual identifier called the “slug”. Normally, slugs are assigned by the official plugin directory. For a private/commercial plugin that’s hosted elsewhere you’ll have to make something up. If unsure, just use the plugin’s file name without the “.php” extension (my-cool-plugin/my-cool-plugin.php becomes my-cool-plugin).

Upload the metadata file you just created to your web server. It doesn’t matter where exactly you put the file or how you name it. The important thing is for its URL to be accessible from wherever someone might install your plugin.

Next, copy the “plugin-update-checker” directory from the client library archive to your plugin’s directory. Then fire up your favourite code editor and add the following lines to the top of your plugin file:

require 'plugin-update-checker/plugin-update-checker.php';
$MyUpdateChecker = PucFactory::buildUpdateChecker(
    'https://example.com/path/to/metadata.json',
    __FILE__,
    'your-chosen-slug'
);

If you followed my advice and used the plugin’s file name as the slug, you can omit the third parameter of the PucFactory::buildUpdateChecker() call.

Tip: Sometimes you’ll run into a situation where another active plugin is also using this update checker. As a result, there could be several different versions of the library loaded at the same time. The above code snippet will always give you the latest available version. This can be a problem if your plugin expects an older version and is not API-compatible with the latest version.

To use a specific version of the update checker (e.g. the one included with your plugin), instantiate the PluginUpdateChecker_x_y class directly. Replace x and y with the major and minor version numbers:

//Use version 2.0 of the update checker.
require 'plugin-update-checker/plugin-update-checker.php';
$MyUpdateChecker = new PluginUpdateChecker_2_0 (
    'https://example.com/path/to/metadata.json',
    __FILE__,
    'your-chosen-slug'
);

And that, believe it or not, is it.

The PluginUpdateChecker class will handle the rest. It’ll check the metadata file every 12 hours and, if it discovers that a new version has been released, twiddle the right bits in the undocumented WP API to make it show up as a standard upgrade notification in the “Plugins” tab. Assuming you’ve provided a valid download_url, users will be able to install the update with a single click.

Tip: When creating the ZIP file for an update, put all plugin files inside a directory. The directory name should match the plugin slug. Do not put the files at the root of the ZIP archive – it can cause subtle bugs and errors when someone ties to install the update.

The rest of this post will be devoted to a more in-depth discussion of the update checker class and the metadata format.

The PluginUpdateChecker class

This class is the core of the update checker. It’s also the only part of the updater that you should need to deal with unless you decide to  extend the library yourself.

Class constructor

All configuration settings should be specified by passing them to the PucFactory::buildUpdateChecker() factory method, or directly to the PluginUpdateChecker constructor. Both takes the following parameters:

  • $metadataUrl – The full URL of the plugin’s metadata file.
  • $pluginFile – The path to the plugin’s file. In most cases you can simply use the __FILE__ constant here.
  • $slug – The plugin’s ‘slug’. If not specified, the filename part of $pluginFile (sans “.php”) will be used as the slug.
  • $checkPeriod – How often to check for updates (in hours). Defaults to checking every 12 hours. Set to zero to disable automatic update checks.
  • $optionName – Where to store book-keeping info about updates. Defaults to “external_updates-$slug”.

checkForUpdates()

Manually trigger an update check. This is especially useful when you’ve disabled automatic checks by setting $checkPeriod (above) to zero. This method takes no parameters and returns nothing.

addQueryArgFilter($callback)

Register a callback for filtering query arguments. Whenever the update checker needs to retrieve the metadata file, it will first run each filter callback and attach the query arguments that they return to the metadata URL. This lets you pass arbitrary data to the server hosting the metadata. For example, commercial plugins could use it to implement some kind of authorization scheme where only users that have the right “key” get automatic updates.

The callback function will be passed an associative array of query arguments and should return a modified array. By default, the update checker will add these arguments to the metadata URL:

  • installed_version – set to the currently installed version of the plugin.
  • checking_for_updates – set to 1 if checking for updates, absent otherwise (i.e. when loading data for the “Plugin Information” box).

This method takes one parameter – the callback function.

addHttpRequestArgFilter($callback)

Register a callback for filtering the various options passed to the built-in helper function wp_remote_get that the update checker uses to periodically download plugin metadata. The callback function should take one argument – an associative array of arguments – and return a modified array or arguments. See the WP documentation on wp_remote_get for details about what arguments are available and how they work.

This method takes one parameter – the callback function.

addResultFilter($callback)

Register a callback for filtering plugin info retrieved from the metadata URL.

The callback function should take two arguments. If the metadata was retrieved successfully, the first argument passed will be an instance of PluginInfo (see the source for a description of this class). Otherwise, it will be NULL. The second argument will be the corresponding return value of wp_remote_get (see WP docs for details). The callback function should return a new or modified instance of PluginInfo or NULL.

This method takes one parameter – the callback function.

Metadata format

The automatic update system uses a JSON-based file format to describe plugins.  Essentially, the entire file is one big JSON-encoded object (AKA hash-table or associative array). Each field – or array key – represents a piece of information about the latest version of the plugin. The full description of all available fields is here.

For the sake of simplicity, both general metadata and update-related information are stored in the same file. If this is undesirable, you can replace the plain JSON file with a script that checks for the presence of the the “checking_for_updates” query parameter and emits just the update-related fields if its set to “1”.

Notes

Your plugin must be active for updates to work. The update checker is just another piece of PHP code loaded and run by your plugin, and it won’t be run if the plugin is inactive.

One consequence of this that may not be immediately obvious is that on a multisite installation updates will only show up if the plugin is active on the main site. This is because update notifications usually appear in the network admin, and only plugins active on the main site are loaded in that case. The main site of a WordPress network is the one that was created first and has the path “/” in the Sites -> All Sites list.

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496 Responses to “Automatic Updates For Private And Commercial Plugins”

  1. Simon says:

    Great. WordPress 3.1 has broken it.

    Call to undefined function get_plugins().

    Anyone else getting this?

  2. White Shadow says:

    Seems to work fine on my test site. You might be using an older version of the library. Re-download it from the “client library” link in the post above.

  3. Simon says:

    Thanks White Shadow,

    Copied over the new plugin-updates directory and no more errors.

    Great!

  4. […] egna uppdateringssystem för att koppla mot sin egen plugin repository. Men, nu hittade jag ett bibliotek som kan användas. Alldeles genialiskt för privata […]

  5. Jared says:

    For some reason, I’m having a huge problem getting this to work. I followed the instructions to the “T” and I’m not getting any errors, but I’m also not getting any updates. 🙁

    Do the version numbers have to be in this format? 1.0 or 2.0, or can it be 1.15b or 1.15a? Is there something I would be doing wrong that’s a common mistake? I tried creating a plugin activation hook to check for updates but the checkForUpdates() function returned an error, undefined function.

  6. Jared says:

    Disregard my last comment, but I got it working now and I’m just having a little problem. It creates a folder with ‘my-plugin-slug’.tmp and does not delete the original and rename the temp folder to the slug. Why is it doing that?

  7. White Shadow says:

    As has been mentioned before, this library doesn’t actually install the update – it only lets WordPress know there is one. Then WP’s built-in plugin updater does the rest. Unfortunately, I have no idea why it (the built-in updater) would fail to rename the temp folder.

  8. […] using this library to auto-update my plugin, but it’s only extracting the new plugin files into a .tmp […]

  9. Jared says:

    I figured out my problem, so if anyone else had the same problem as me, it was because in the zip folder that WP downloads, you should have a folder named after the slug specified in the JSON file, inside that folder should be the plugin contents. I had my plugin files in the top directory of the zip archive. 😉

  10. […] functions plugin/s to update automatically, you can achieve this through the suggestions offered in this excellent post by W-Shadow.ConclusionThe method outlined above is best when you are reusing code over and over […]

  11. Dalton says:

    I have to chime in and offer my appreciation for this library as well. It’s fantastic and does exactly what I needed to do.

    I do have one small issue… when this library active, the Plugin menu in the sidebar shows one available update, even if there are none. Here’s a screenshot: http://cl.ly/2I1a2e422r3y2b103H2c

    All of the plugins are up to date and I have confirmed this on multiple WP installs. As soon as I deactivate the library it goes away. Any idea what might be causing it?

    Thanks,
    Dalton

  12. Dalton says:

    My mistake – I moved my instance of the class from the main plugin file to a functions file in a subdirectory and forgot to update it to reference the correct file when checking for the version. All is working correctly now.

  13. Benjamin says:

    Brilliant work !! Works as intended. Very very good job.

  14. Sisir says:

    How can i make this work for theme updates?

  15. White Shadow says:

    I’m not familiar with how theme updates work in WP, sorry. Perhaps I should look into it. Do you think a theme authors would be interested in a similar library that enables automatic updates for private/commercial themes?

  16. Dalton says:

    I would definitely be interested in autoupdates for private themes, and would gladly pay for it. I’d also be happy to make a donation for this library – what’s the best way to do that?

    Thanks,
    Dalton

  17. Sisir says:

    @White Shadow: Yes, i think so. The the big theme authors does have their own system for notifying people for theme updates. Some of those via RSS. But i think this kinda library will help lots of mid level commercial theme developer.

    In my case. I have a theme that i installed in 7 sites so when i improve my theme i have to ftp the new files to the 7 places. So, it will certainly very helpful for me 🙂

  18. White Shadow says:

    @Dalton:
    That’s good to hear. Any specific features you’d be looking for? Regarding donations, feel free to send a few bucks to my PayPal account: whiteshadow@w-shadow.com

    @Sisir:
    Okay, I’ll definitely consider building it.


    Overall, maybe a workable model might be a library that’s free for non-commercial/personal use, but costs money to use in a commercial theme.

  19. Sisir says:

    @White Shadow: You should try adding a “Buy me a coffee” button in your sidebar 😉

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