Replace mu-plugin with a format consistent with pantheon-systems/pant…

…heon-mu-plugin

This update aligns the Pantheon mu-plugin format to our standalone repository (https://github.com/pantheon-systems/pantheon-mu-plugin), and will allow
for the mu-plugin to receive updates from that repo whenever an updated version of WordPress is released.

For more information, see https://pantheon.io/docs/start-states/wordpress#2022-11-01

wp-content/mu-plugins/loader.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * Plugin Name: Pantheon MU Plugin Loader
+ * Description: Loads the MU plugins required to run the site
+ * Author: Pantheon Systems
+ * Author URI: https://pantheon.io
+ * Version: 1.0
+ */
+
+if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
+	return;
+}
+
+// Add mu-plugins here.
+$pantheon_mu_plugins = [
+	'pantheon-mu-plugin/pantheon.php',
+];
+
+foreach ( $pantheon_mu_plugins as $file ) {
+	require_once WPMU_PLUGIN_DIR . '/' . $file;
+}
+unset( $file );
+
+add_action( 'pre_current_active_plugins', function () use ( $pantheon_mu_plugins ) {
+	global $plugins, $wp_list_table;
+
+	// Add our own mu-plugins to the page.
+	foreach ( $pantheon_mu_plugins as $plugin_file ) {
+		// Do not apply markup/translate as it'll be cached.
+		$plugin_data = get_plugin_data( WPMU_PLUGIN_DIR . "/$plugin_file", false, false );
+
+		if ( empty( $plugin_data['Name'] ) ) {
+			$plugin_data['Name'] = $plugin_file;
+		}
+
+		$plugins['mustuse'][ $plugin_file ] = $plugin_data;
+	}
+
+	// Recount totals.
+	$GLOBALS['totals']['mustuse'] = count( $plugins['mustuse'] );
+
+	// Only apply the rest if we're actually looking at the page.
+	if ( $GLOBALS['status'] !== 'mustuse' ) {
+		return;
+	}
+
+	// Reset the list table's data.
+	$wp_list_table->items = $plugins['mustuse'];
+	foreach ( $wp_list_table->items as $plugin_file => $plugin_data ) {
+		$wp_list_table->items[ $plugin_file ] = _get_plugin_data_markup_translate( $plugin_file, $plugin_data, false, true );
+	}
+
+	$total_this_page = $GLOBALS['totals']['mustuse'];
+
+	if ( $GLOBALS['orderby'] ) {
+		uasort( $wp_list_table->items, [ $wp_list_table, '_order_callback' ] );
+	}
+
+	// Force showing all plugins.
+	// See https://core.trac.wordpress.org/ticket/27110.
+	$plugins_per_page = $total_this_page;
+
+	$wp_list_table->set_pagination_args( [
+		'total_items' => $total_this_page,
+		'per_page'    => $plugins_per_page,
+	] );
+});
+
+add_filter( 'network_admin_plugin_action_links', function ( $actions, $plugin_file, $plugin_data, $context ) use ( $pantheon_mu_plugins ) {
+	if ( $context !== 'mustuse' || ! in_array( $plugin_file, $hm_mu_plugins, true ) ) {
+		return $actions;
+	}
+
+	$actions[] = sprintf( '<span style="color:#333">File: <code>%s</code></span>', $plugin_file );
+	return $actions;
+}, 10, 4 );

wp-content/mu-plugins/pantheon/pantheon-page-cache.php → wp-content/mu-plugins/pantheon-mu-plugin/inc/pantheon-page-cache.php

@@ -95,7 +95,12 @@ protected function setup() {
 
 		add_action( 'admin_post_pantheon_cache_flush_site',  array( $this, 'flush_site' ) );
 
-		add_action( 'send_headers',       array( $this, 'cache_add_headers' ) );
+		if ( ! is_admin() && function_exists( 'is_user_logged_in' ) && ! is_user_logged_in() ) {
+			add_action( 'send_headers',               array( $this, 'cache_add_headers' ) );
+		}
+		else {
+			add_action( 'send_headers',               array( $this, 'no_cache_add_headers' ) );
+		}
 		add_filter( 'rest_post_dispatch', array( $this, 'filter_rest_post_dispatch_send_cache_control' ), 10, 2 );
 
 		add_action( 'admin_notices', function(){
@@ -328,24 +333,15 @@ public function view_settings_page() {
 	}
 
 	/**
-	 * Get the cache-control header value
+	 * Set a stronger cache-control header for admin or logged in requests.
 	 *
 	 * This removes "max-age=0" which could hypothetically be used by
 	 * Varnish on an immediate subsequent request.
 	 *
 	 * @return void
 	 */
-	private function get_cache_control_header_value() {
-		if ( ! is_admin() && ! is_user_logged_in() ) {
-			$ttl = absint( $this->options['default_ttl'] );
-			if ( $ttl < 60 && isset( $_ENV['PANTHEON_ENVIRONMENT'] ) && 'live' === $_ENV['PANTHEON_ENVIRONMENT'] ) {
-				$ttl = 60;
-			}
-
-			return sprintf( 'public, max-age=%d', $ttl );
-		} else {
-			return 'no-cache, no-store, must-revalidate';
-		}
+	public function no_cache_add_headers() {
+		header( 'cache-control: no-cache, no-store, must-revalidate');
 	}
 
 	/**
@@ -354,17 +350,23 @@ private function get_cache_control_header_value() {
 	 * @return void
 	 */
 	public function cache_add_headers() {
-		header( sprintf( 'cache-control: %s', $this->get_cache_control_header_value() ) );
+		$ttl = absint( $this->options['default_ttl'] );
+		if ( $ttl < 60 && isset( $_ENV['PANTHEON_ENVIRONMENT'] ) && 'live' === $_ENV['PANTHEON_ENVIRONMENT'] ) {
+			$ttl = 60;
+		}
+
+		header( 'cache-control: public, max-age=' . $ttl );
 	}
 
 	/**
 	 * Send the cache control header for REST API requests
-	 * 
-	 * @param WP_REST_Response $response Response.
-	 * @return WP_REST_Response Response.
 	 */
-	public function filter_rest_post_dispatch_send_cache_control( $response ) {
-		$response->header( 'Cache-Control', $this->get_cache_control_header_value() );
+	public function filter_rest_post_dispatch_send_cache_control( $response, $server ) {
+		$ttl = absint( $this->options['default_ttl'] );
+		if ( $ttl < 60 && isset( $_ENV['PANTHEON_ENVIRONMENT'] ) && 'live' === $_ENV['PANTHEON_ENVIRONMENT'] ) {
+			$ttl = 60;
+		}
+		$response->header( 'Cache-Control', 'public, max-age=' . $ttl );
 		return $response;
 	}
 

wp-content/mu-plugins/pantheon.php → wp-content/mu-plugins/pantheon-mu-plugin/pantheon.php

@@ -3,7 +3,7 @@
  * Plugin Name: Pantheon
  * Plugin URI: https://pantheon.io/
  * Description: Building on Pantheon's and WordPress's strengths, together.
- * Version: 0.3
+ * Version: 1.0.0
  * Author: Pantheon
  * Author URI: https://pantheon.io/
  *
@@ -12,18 +12,18 @@
 
 if ( isset( $_ENV['PANTHEON_ENVIRONMENT'] ) ) {
 
-	require_once 'pantheon/pantheon-page-cache.php';
+	require_once 'inc/pantheon-page-cache.php';
 	if ( ! defined( 'DISABLE_PANTHEON_UPDATE_NOTICES' ) || ! DISABLE_PANTHEON_UPDATE_NOTICES ) {
-		require_once 'pantheon/pantheon-updates.php';
+		require_once 'inc/pantheon-updates.php';
 	}
 	if ( ! defined('RETURN_TO_PANTHEON_BUTTON') || RETURN_TO_PANTHEON_BUTTON ) {
-		require_once 'pantheon/pantheon-login-form-mods.php';
+		require_once 'inc/pantheon-login-form-mods.php';
 	}
 	if ( 'dev' === $_ENV['PANTHEON_ENVIRONMENT'] && function_exists( 'wp_is_writable' ) ) {
-		require_once 'pantheon/pantheon-plugin-install-notice.php';
+		require_once 'inc/pantheon-plugin-install-notice.php';
 	}
     if ( defined( 'WP_CLI' ) && WP_CLI ) {
-        require_once 'pantheon/cli.php';
+        require_once 'inc/cli.php';
     }
 	if ( ! defined( 'FS_METHOD' ) ) {
 		/**