Enable Object Cache

terminus wp <site>.<env> -- plugin install wp-redis

terminus wp <site>.<env> -- plugin install wp-redis --url=<url>

<?php
# This is a Windows-friendly symlink
$objectCacheFile = WP_CONTENT_DIR . '/plugins/wp-redis/object-cache.php';
if (!empty($_ENV['PANTHEON_ENVIRONMENT']) && !empty($_ENV['CACHE_HOST']) && file_exists($objectCacheFile)) {
    require_once $objectCacheFile;
}

terminus wp <site>.<env> -- plugin update wp-redis

terminus remote:drush <site>.<env> -- en redis -y

// All Pantheon Environments.
if (!empty($_ENV['PANTHEON_ENVIRONMENT']) && !empty($_ENV['CACHE_HOST'])) {
  // Use Redis for caching.
  $conf['redis_client_interface'] = 'PhpRedis';
  // Point Drupal to the location of the Redis plugin.
  $conf['cache_backends'][] = 'sites/all/modules/redis/redis.autoload.inc';
  // If you've installed your plugin in a contrib directory, use this line instead:
  // $conf['cache_backends'][] = 'sites/all/modules/contrib/redis/redis.autoload.inc';
  $conf['cache_default_class'] = 'Redis_CacheCompressed';
  $conf['cache_prefix'] = array('default' => 'pantheon-redis');
  // Do not use Redis for cache_form (no performance difference).
  $conf['cache_class_cache_form'] = 'DrupalDatabaseCache';
  // Use Redis for Drupal locks (semaphore).
  $conf['lock_inc'] = 'sites/all/modules/redis/redis.lock.inc';
  // Or if you've installed the redis module in a contrib subdirectory, use:
  // $conf['lock_inc'] = 'sites/all/modules/contrib/redis/redis.lock.inc';
}

terminus connection:set $SITE.dev git
terminus redis:enable $SITE
composer require drupal/redis
git add . && git commit -m "Add drupal/redis dependency" && git push origin master

terminus connection:set $SITE.dev sftp
terminus drush $SITE.dev -- en redis -y
terminus drush $SITE.dev -- config:export -y
terminus env:commit $SITE.dev --message="Enable Redis, export configuration"

// Configure Redis

if (defined(
 'PANTHEON_ENVIRONMENT'
) && !\Drupal\Core\Installer\InstallerKernel::installationAttempted(
) && extension_loaded('redis')) {
 // Set Redis as the default backend for any cache bin not otherwise specified.
 $settings['cache']['default'] = 'cache.backend.redis';

 //phpredis is built into the Pantheon application container.
 $settings['redis.connection']['interface'] = 'PhpRedis';

 // These are dynamic variables handled by Pantheon.
 $settings['redis.connection']['host'] = $_ENV['CACHE_HOST'];
 $settings['redis.connection']['port'] = $_ENV['CACHE_PORT'];
 $settings['redis.connection']['password'] = $_ENV['CACHE_PASSWORD'];

 $settings['redis_compress_length'] = 100;
 $settings['redis_compress_level'] = 1;

 $settings['cache_prefix']['default'] = 'pantheon-redis';

 $settings['cache']['bins']['form'] = 'cache.backend.database'; // Use the database for forms

 // Apply changes to the container configuration to make better use of Redis.
 // This includes using Redis for the lock and flood control systems, as well
 // as the cache tag checksum. Alternatively, copy the contents of that file
 // to your project-specific services.yml file, modify as appropriate, and
 // remove this line.
 $settings['container_yamls'][] = 'modules/contrib/redis/example.services.yml';

 // Allow the services to work before the Redis module itself is enabled.
 $settings['container_yamls'][] = 'modules/contrib/redis/redis.services.yml';

 // Manually add the classloader path, this is required for the container
 // cache bin definition below.
 $class_loader->addPsr4('Drupal\\redis\\', 'modules/contrib/redis/src'); 

 // Use redis for container cache.
 // The container cache is used to load the container definition itself, and
 // thus any configuration stored in the container itself is not available
 // yet. These lines force the container cache to use Redis rather than the
 // default SQL cache.
 $settings['bootstrap_container_definition'] = [
   'parameters' => [],
   'services' => [
     'redis.factory' => [
       'class' => 'Drupal\redis\ClientFactory',
     ],
     'cache.backend.redis' => [
       'class' => 'Drupal\redis\Cache\CacheBackendFactory',
       'arguments' => [
         '@redis.factory',
         '@cache_tags_provider.container',
         '@serialization.phpserialize',
       ],
     ],
     'cache.container' => [
       'class' => '\Drupal\redis\Cache\PhpRedis',
       'factory' => ['@cache.backend.redis', 'get'],
       'arguments' => ['container'],
     ],
     'cache_tags_provider.container' => [
       'class' => 'Drupal\redis\Cache\RedisCacheTagsChecksum',
       'arguments' => ['@redis.factory'],
     ],
     'serialization.phpserialize' => [
       'class' => 'Drupal\Component\Serialization\PhpSerialize',
     ],
   ],
 ];
}