Prevent cache collisions in multisite db-update tasks (acquia#3166)

* Add drush cache dir utility script.

* Enhanced Factory Hook to isolate db-update tasks to tempoary drush cache.

* Update Factory Hooks from BLT template.

* Remove redundant cache clear and rebuild to preserve drush context of current request.

* Style tweaks and setting update version number to 9.2.

scripts/blt/drush/cache.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @file
+ * Creates a unique temporary cache directory given a site, env, and uri.
+ * This is used for every blt command invocation on site install and update.
+ */
+
+$site = $argv[1];
+$env = $argv[2];
+$uri = $argv[3];
+
+
+if (empty($argv[3])) {
+  echo "Error: Not enough arguments. Site, environment, and uri are required.\n";
+  exit(1);
+}
+
+// Create a temporary cache directory for this drush process only.
+$cache_directory = sprintf('/mnt/tmp/%s.%s/drush_tmp_cache/%s', $site, $env, md5($uri));
+shell_exec(sprintf('mkdir -p %s', escapeshellarg($cache_directory)));
+
+if (!file_exists($cache_directory)) {
+  syslog(LOG_ERR, sprintf('Drush updates could not be executed, as the required cache directory [%s] is missing.', $cache_directory));
+  die('Missing or corrupted drush cache for this process.');
+}
+else {
+  echo "$cache_directory";
+}

scripts/factory-hooks/db-update/db-update.sh

@@ -18,21 +18,27 @@ db_role="$3"
 domain="$4"
 
 # BLT executable:
-blt="/var/www/html/$site.$env/vendor/acquia/blt/bin/blt"
+blt="/mnt/www/html/$site.$env/vendor/acquia/blt/bin/blt"
 
 # You need the URI of the site factory website in order for drush to target that
 # site. Without it, the drush command will fail. Use the uri.php file provided by the acsf module to
 # locate the URI based on the site, environment and db role arguments.
 uri=`/usr/bin/env php /mnt/www/html/$site.$env/hooks/acquia/uri.php $site $env $db_role`
 
-# Print a statement to the cloud log.
-echo "$site.$target_env: Running BLT deploy tasks on $uri domain in $env environment on the $site subscription."
-
+# Create array with site name fragments from ACSF uri. 
 IFS='.' read -a name <<< "${uri}"
 
-# Set Drush cache to local ephemeral storage to avoid race conditions. This is
-# done on a per site basis to completely avoid race conditions.
-# @see https://github.com/acquia/blt/pull/2922
-export DRUSH_PATHS_CACHE_DIRECTORY=/tmp/.drush/${db_role}
+# Create and set Drush cache to unique local temporary storage per site.
+# This approach isolates drush processes to completely avoid race conditions
+# that persist after initial attempts at addressing in BLT: https://github.com/acquia/blt/pull/2922
+
+cacheDir=`/usr/bin/env php /mnt/www/html/$site.$env/vendor/acquia/blt/scripts/blt/drush/cache.php $site $env $uri`
+
+# Print to cloud task log.
+echo "Generated temporary drush cache directory: $cacheDir."
+
+# Print to cloud task log.
+echo "Running BLT deploy tasks on $uri domain in $env environment on the $site subscription."
+
+DRUSH_PATHS_CACHE_DIRECTORY=$cacheDir $blt drupal:update --environment=$env --site=${name[0]} --define drush.uri=$domain --verbose --yes --no-interaction
 
-$blt drupal:update --environment=$env --site=${name[0]} --define drush.uri=$domain --verbose --yes

src/Robo/Commands/Setup/ConfigCommand.php

@@ -53,11 +53,6 @@ public function import() {
 
       $task = $this->taskDrush()
         ->stopOnFail()
-        // Sometimes drush forgets where to find its aliases.
-        ->drush("cc")->arg('drush')
-        // Rebuild caches in case service definitions have changed.
-        // @see https://www.drupal.org/node/2826466
-        ->drush("cache-rebuild")
         // Execute db updates.
         // This must happen before features are imported or configuration is
         // imported. For instance, if you add a dependency on a new extension to

src/Update/Updates.php

@@ -564,7 +564,7 @@ public function update_9001000() {
     // Update composer.json to include new BLT required/suggested files.
     // Pulls in wikimedia/composer-merge-plugin and composer/installers settings.
     $project_composer_json = $this->updater->getRepoRoot() . '/composer.json';
-    $template_composer_json = $this->updater->getBltRoot() . '/subtree-splits/blt-project/composer.json';
+    $template_composer_json = $this->updater->getBltRoot() . '/template/composer.json';
     $munged_json = ComposerMunge::mungeFiles($project_composer_json, $template_composer_json);
     $bytes = file_put_contents($project_composer_json, $munged_json);
     if (!$bytes) {
@@ -606,6 +606,28 @@ public function update_9001001() {
     $this->updater->getOutput()->writeln("");
   }
 
+  /**
+   * 9.2.0.
+   *
+   * @Update(
+   *    version = "9002000",
+   *    description = "Factory Hooks Drush 9 bug fixes and enhancements."
+   * )
+   */
+  public function update_9002000() {
+    if (file_exists($this->updater->getRepoRoot() . '/factory-hooks')) {
+      $messages = [
+        "This update will update the files in your existing factory hooks directory.",
+        "Review the resulting files and ensure that any customizations have been re-added.",
+      ];
+      $this->updater->executeCommand("./vendor/bin/blt recipes:acsf:init:hooks");
+    }
+    $formattedBlock = $this->updater->getFormatter()->formatBlock($messages, 'ice');
+    $this->updater->getOutput()->writeln("");
+    $this->updater->getOutput()->writeln($formattedBlock);
+    $this->updater->getOutput()->writeln("");
+  }
+
   /**
    * 10.0.0.
    *
@@ -632,7 +654,6 @@ public function update_10000000() {
       $composer_json[$sync_composer_key] = ArrayManipulator::arrayMergeRecursiveDistinct( $composer_json[$sync_composer_key], $template_composer_json[$sync_composer_key]);
     }
     $composer_json['require-dev']['acquia/blt-require-dev'] = $template_composer_json['require']['acquia/blt-require-dev'];
-
     $this->updater->writeComposerJson($composer_json);
     $messages = [
       "Your composer.json file has been modified to remove the Composer merge plugin.",