Add support for PHP-FPM error backtraces and session upload progress

- Introduce `PHP_FPM_FATAL_ERROR_BACKTRACES` and `PHP_FPM_SESSION_UPLOAD_PROGRESS_ENABLED` environment variables with defaults.
- Configure `fatal_error_backtraces` and `session.upload_progress.enabled` in `app-fpm.conf`.

app/docker/php/conf/app-fpm.conf

@@ -10,6 +10,8 @@ php_admin_value[post_max_size] = ${PHP_FPM_POST_MAX_SIZE}
 php_admin_value[display_errors] = ${PHP_FPM_DISPLAY_ERRORS}
 php_admin_value[opcache.enable] = ${PHP_FPM_OPCACHE_ENABLE}
 php_admin_value[opcache.validate_timestamps] = ${PHP_FPM_OPCACHE_VALIDATE_TIMESTAMPS}
+php_admin_value[session.upload_progress.enabled] = ${PHP_FPM_SESSION_UPLOAD_PROGRESS_ENABLED}
+php_admin_value[fatal_error_backtraces] = ${PHP_FPM_FATAL_ERROR_BACKTRACES}
 
 pm = dynamic
 pm.max_children = ${PHP_FPM_PM_MAX_CHILDREN}

app/docker/php/start.sh

@@ -22,6 +22,9 @@ if [ "$role" = "app" ]; then
   export PHP_FPM_PM_MAX_SPARE_SERVERS="${PHP_FPM_PM_MAX_SPARE_SERVERS:-5}"
   export PHP_FPM_PM_MAX_REQUESTS="${PHP_FPM_PM_MAX_REQUESTS:-500}"
 
+  export PHP_FPM_FATAL_ERROR_BACKTRACES="${PHP_FPM_FATAL_ERROR_BACKTRACES:-0}"
+  export PHP_FPM_SESSION_UPLOAD_PROGRESS_ENABLED="${PHP_FPM_SESSION_UPLOAD_PROGRESS_ENABLED:-0}"
+
   if [ "$APP_ENV" = "production" ]; then
     export PHP_FPM_DISPLAY_ERRORS="${PHP_FPM_DISPLAY_ERRORS:-0}"
     export PHP_FPM_OPCACHE_ENABLE="${PHP_FPM_OPCACHE_ENABLE:-1}"