Version 1

[yaffs-website] / vendor / drush / drush / docs / config-filter.md

diff --git a/vendor/drush/drush/docs/config-filter.md b/vendor/drush/drush/docs/config-filter.md
new file mode 100644 (file)
index 0000000..8cea797
--- /dev/null
+++ b/vendor/drush/drush/docs/config-filter.md
@@ -0,0 +1,66 @@
+# Filtering Drupal Configuration
+
+When exporting and importing configuration from and to a Drupal 8 site,
+Drush provides a mechanism called the Configuration Filter system which 
+allows configuration values to be altered during import and export, allowing 
+you to vary your configuration by environment.  The --skip-modules option
+in the config-import and config-export commands is implemented with a
+configuration filter.  For more complex uses, you will need to write some
+custom code.
+
+## Other Alternatives
+
+The Drupal Configuration system provides the capability to [add configuration
+overrides from modules](https://www.drupal.org/node/1928898).  Configuration
+overrides should be provided from a module override when possible.  Implementing
+an override via a Drush extension is convenient in situations where you would
+like to be able to pass values in to the configuration filter via a Drush
+commandline option.
+
+## Filtering Drupal Configuration with Drush
+
+Instructions on writing a Drush extension to filter Drupal configuration follows.
+
+### Getting started
+
+The first thing that you will need to do is set up a Drush extension
+to hold your storage filter hook.  See the example
+[example sandwich commandfile](../examples/sandwich-drush.inc) for
+details; note, however, that it is not necessary for your commandfile
+to implement hook_drush_command(), or any other hook besides the storage
+filter hook.
+
+You will need a composer.json file as well, in order to define where
+your StorageFilter class is defined.  Make sure that Drush and your
+custom commandfile are required from the composer.json file of any
+Drupal site that you plan on using your filter with.
+
+### Implementing the Storage Filter Hook
+
+When Drush imports or exports configuration, it gives all Drush
+extensions a chance to hook this process by way of the hook
+hook_drush_storage_filters.  The implementation of this hook,
+in the file MYFILTER.drush.inc, would look like this:
+```
+function MYFILTER_drush_storage_filters() {
+  $result = array();
+  $my_option = drush_get_option('my-option');
+  if (!empty($my_option)) {
+    $result[] = new MyConfigurationFilter($my_option);
+  }
+  return $result;
+}
+```
+With this hook in place, MyConfigurationFilter will become part of
+the import / export process.
+
+### Implementing a Storage Filter
+
+It is necessary to implement a class that implements 
+[StorageFilter](https://github.com/drush-ops/drush/blob/master/lib/Drush/Config/StorageFilter.php).
+Your class only needs to implement the two methods defined there,
+filterRead() and filterWrite(), to make whichever alterations to configuration
+you need during the export and import operations, respectively.  For
+an example class that implements StorageFilter, see the
+[CoreExtensionFilter](https://github.com/drush-ops/drush/blob/master/lib/Drush/Config/CoreExtensionFilter.php)
+class.