nippet to allow setting UpdraftPlus settings via wp-config.php constants

mainwp-updraft.php

<?php 

/**
 * Allows setting UpdraftPlus settings via wp-config.php constants
 *
 * Usefull for setting AWS S3 Access/Secret Keys in a constant instead of saving it in the database
 * Set the constant UPDRAFT_S3_SETTINGS with configuration like this:
 * ```php
 * define('UPDRAFT_S3_SETTINGS', [
 *  'accesskey' => 'accesskey',
 *  'secretkey' => 'secretkey',
 *  'path' => '$BUCKET/$DIR'
 * ]);
 * ```
 *
 * For available keys setup a job via UI and look at the serialized value in the database
 * accesskey, secretkey, path ($BUCKET/$DIR)
 */

/**
 * Merges the settings when get for backend UI display (prepare for template)
 * Hooked on `updraftplus_options_s3_options`
 */
function mwp_mergeUpdraftSettingsTemplate($options)
{
    if (!defined('UPDRAFT_S3_SETTINGS') || !UPDRAFT_S3_SETTINGS) {
        return $options;
    }

    $options = array_merge($options, UPDRAFT_S3_SETTINGS);
    return $options;
}
add_filter('updraftplus_options_s3_options', 'mwp_mergeUpdraftSettingsTemplate');

/**
 * Merges the settings when get for checking anywhere by Updraft
 * Hooked on `updraftplus_get_option`
 */
function mwp_mergeUpdraftSettingsOption($value, $option) {
    if ($option !== 'updraft_s3' && $option !== 'updraft_s3generic') {
        return $value;
    }

    if (!defined('UPDRAFT_S3_SETTINGS') || !UPDRAFT_S3_SETTINGS) {
        return $value;
    }

    if (!isset($value['settings']) || !$value['settings']) { // no instance created yet
        return $value;
    }
    foreach ($value['settings'] as $instanceId => $instanceSettings) {
        foreach ($instanceSettings as $key => $val) {
            if (!isset(UPDRAFT_S3_SETTINGS[$key])) {
                continue;
            }
            $value['settings'][$instanceId][$key] = UPDRAFT_S3_SETTINGS[$key]; // overwrite with constant value
        }
    }
    return $value;
}
add_filter('updraftplus_get_option', 'mwp_mergeUpdraftSettingsOption', 10, 2);

/**
 * Prevents from overwriting UpdraftPlus settings defined via constants in the backend UI
 *
 * Loops through all jobs and optionKeys and checks if they are defined in the constant,
 * if yes an empty string is saved to the database
 *
 * Hooked on `updraftplus_update_option`
 */
function mwp_mergeUpdraftSettingsOnSave($value, $option)
{
    if ($option !== 'updraft_s3' && $option !== 'updraft_s3generic') {
        return $value;
    }

    if (!defined('UPDRAFT_S3_SETTINGS') || !UPDRAFT_S3_SETTINGS) {
        return $value;
    }

    foreach ($value['settings'] as $instanceId => $instanceSettings) {
        foreach ($instanceSettings as $key => $val) {
            if (!isset(UPDRAFT_S3_SETTINGS[$key])) {
                continue;
            }
            $value['settings'][$instanceId][$key] = ''; // reset to empty
        }
    }
    return $value;
}
add_filter('updraftplus_update_option', 'mwp_mergeUpdraftSettingsOnSave', 10, 2);

/**
 * Makes the constant-defined settings readonly/disabled in the backend UI
 *
 * Hooked on `admin_footer-settings_page_updraftplus`
 */
function mwp_disableUpdraftSettingsInputs()
{
    if (!defined('UPDRAFT_S3_SETTINGS') || !UPDRAFT_S3_SETTINGS) {
        return;
    }

    $readableKeysSelectorString = implode(',', array_map(function ($k) {
        return "[id^='updraft_s3_{$k}_']";
    }, array_keys(UPDRAFT_S3_SETTINGS)));
?>
    <script>
        (function($) {
            $(function() {
                $("<?php echo $readableKeysSelectorString; ?>").attr("readonly", true).attr("disabled", true);
            });
        })(jQuery)
    </script>
<?php
}
add_action('admin_footer-settings_page_updraftplus', 'mwp_disableUpdraftSettingsInputs');