PHP Fatal error: Uncaught Error: Call to undefined function cache_get() I'm trying to get Drupal to work inside an Alpine Linux docker container but for some reason drush can't be used to manage the website. The website itselfactually works fine, drush just can't bootstrap.

Here's the pertinent information:

 /var/www/html # drush core-status
 Drupal version         :  7.56                        
 Site URI               :  http://default              
 Database driver        :  mysql                       
 Database hostname      :  vlp-dcimysql01.dhe.duke.edu 
 Database port          :                              
 Database username      :  tmp_drupal                  
 Database name          :  tmp_drupal                  
 PHP configuration      :  /etc/php7/php.ini           
 PHP OS                 :  Linux                       
 Drush script           :  /usr/bin/drush              
 Drush version          :  8.1.14                      
 Drush temp directory   :  /tmp                        
 Drush configuration    :                              
 Drush alias files      :                              
 Drupal root            :  /var/www/html               
 Drupal Settings File   :  sites/default/settings.php  
 Site path              :  sites/default               

/var/www/html # drush wd-show
PHP Fatal error:  Uncaught Error: Call to undefined function cache_get() in /var/www/html/includes/module.inc:754
Stack trace:
#0 /var/www/html/includes/module.inc(954): module_implements('system_theme_in...')
#1 /var/www/html/modules/system/system.module(2511): module_invoke_all('system_theme_in...')
#2 /var/www/html/includes/theme.inc(798): _system_rebuild_theme_data()
#3 /var/www/html/includes/theme.maintenance.inc(57): list_themes()
#4 /var/www/html/includes/bootstrap.inc(2872): _drupal_maintenance_theme()
#5 /var/www/html/includes/errors.inc(179): drupal_maintenance_theme()
#6 /var/www/html/includes/bootstrap.inc(2609): _drupal_log_error(Array, true)
#7 [internal function]: _drupal_exception_handler(Object(Error))
#8 {main}
  thrown in /var/www/html/includes/module.inc on line 754
Drush command terminated abnormally due to an unrecoverable error.                                                                                                                                                                     [error]
Error: Uncaught Error: Call to undefined function cache_get() in /var/www/html/includes/module.inc:754
Stack trace:
#0 /var/www/html/includes/module.inc(954): module_implements('system_theme_in...')
#1 /var/www/html/modules/system/system.module(2511): module_invoke_all('system_theme_in...')
#2 /var/www/html/includes/theme.inc(798): _system_rebuild_theme_data()
#3 /var/www/html/includes/theme.maintenance.inc(57): list_themes()
#4 /var/www/html/includes/bootstrap.inc(2872): _drupal_maintenance_theme()
#5 /var/www/html/includes/errors.inc(179): drupal_maintenance_theme()
#6 /var/www/html/includes/bootstrap.inc(2609): _drupal_log_error(Array, true)
#7 [internal function]: _drupal_exception_handler(Object(Error))
#8 {main}
  thrown in /var/www/html/includes/module.inc, line 754


As stated before, the platform is Alpine Linux, PHP is 7.1.9

I can add more if anything is unclear. I've checked the PHP logs but they just produce the above output. I'm open to there just being a module/extension missing, but I'm not entirely sure how to figure that out if it doesn't ever tell me "undefined function extensionFunctionX" or something like that. The above undefined function appears to be a Drupal core function.

Note that the website works, so it's communicating with the database without issue, I can also do a SHOW TABLES in MySQL and see the Drupal installer's tables were created.
In my case (moving production website to fresh server) memcached was enabled in settings.php, PHP daemon was installed and running on server, but no PHP extension was installed