diff --git a/config/schema/facets.facetsource.schema.yml b/config/schema/facets.facetsource.schema.yml
new file mode 100644
index 0000000000000000000000000000000000000000..962703ef7790b0caeceb2666a98b864afa6396b8
--- /dev/null
+++ b/config/schema/facets.facetsource.schema.yml
@@ -0,0 +1,16 @@
+facets.facet_source.*:
+  type: config_entity
+  label : 'Facet Source'
+  mapping:
+    uuid:
+      type: string
+      label: 'UUID'
+    id:
+      type: string
+      label: 'ID'
+    name:
+      type: label
+      label: Name'
+    filterKey:
+      type: string
+      label: 'Filter key'
diff --git a/core_search_facets/src/Plugin/CoreSearchFacetSourceInterface.php b/core_search_facets/src/Plugin/CoreSearchFacetSourceInterface.php
index fa16be56bce0f1b038396ca0094c0ec387e4d885..24486a2b04070cc9d07b679c55eca63c1325e5a0 100644
--- a/core_search_facets/src/Plugin/CoreSearchFacetSourceInterface.php
+++ b/core_search_facets/src/Plugin/CoreSearchFacetSourceInterface.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains \Drupal\core_search_facets\Plugin\FacetSourceInterface.
+ * Contains \Drupal\core_search_facets\Plugin\CoreSearchFacetSourceInterface.
  */
 
 namespace Drupal\core_search_facets\Plugin;
@@ -14,7 +14,7 @@ use Drupal\facets\FacetInterface;
  *
  * A facet source is used to abstract the data source where facets can be added
  * to. A good example of this is a search api view. There are other possible
- * facet data sources, these all implement the FacetSourceInterface.
+ * facet data sources, these all implement the FacetSourcePluginInterface.
  */
 interface CoreSearchFacetSourceInterface {
 
diff --git a/core_search_facets/src/Plugin/facets/facet_source/CoreNodeSearchFacetSource.php b/core_search_facets/src/Plugin/facets/facet_source/CoreNodeSearchFacetSource.php
index 38b135e61ad0faa084b1a45393e43fdab44dfc94..12e63198d4d2ddf6161dd22e10c0c92a8ea654ad 100644
--- a/core_search_facets/src/Plugin/facets/facet_source/CoreNodeSearchFacetSource.php
+++ b/core_search_facets/src/Plugin/facets/facet_source/CoreNodeSearchFacetSource.php
@@ -12,10 +12,9 @@ use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\core_search_facets\Plugin\CoreSearchFacetSourceInterface;
 use Drupal\facets\FacetInterface;
-use Drupal\facets\FacetSource\FacetSourceInterface;
 use Drupal\facets\FacetSource\FacetSourcePluginBase;
+use Drupal\facets\FacetSource\FacetSourcePluginInterface;
 use Drupal\field\Entity\FieldConfig;
-use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\search\SearchPageInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
@@ -178,7 +177,7 @@ class CoreNodeSearchFacetSource extends FacetSourcePluginBase implements CoreSea
   /**
    * {@inheritdoc}
    */
-  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourceInterface $facet_source) {
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourcePluginInterface $facet_source) {
 
     $form['field_identifier'] = [
       '#type' => 'select',
diff --git a/facets.routing.yml b/facets.routing.yml
index 576dd647948aac4a1cc1bcf0d2545e9d04563519..5202aa7f6b1ed5b70a88d6e5c82f3316723d68b0 100644
--- a/facets.routing.yml
+++ b/facets.routing.yml
@@ -41,3 +41,12 @@ entity.facets_facet.display_form:
     _entity_form: 'facets_facet.display'
   requirements:
     _entity_access: 'facets_facet.edit'
+
+
+entity.facets_facetsource.edit_form:
+  path: '/admin/config/search/facets/facet-sources/{source_id}/edit'
+  defaults:
+    _controller: '\Drupal\facets\Controller\FacetSourceController::facetSourceConfigForm'
+    _title: 'Edit facet source configuration'
+  requirements:
+    _entity_create_access: 'facets_facet'
diff --git a/src/Annotation/FacetsFacetSource.php b/src/Annotation/FacetsFacetSource.php
index bfe425c8ce7843256a80adff6d381f93822e4075..7389e311a746468f4de0b41cd7df04fdb0c5d317 100644
--- a/src/Annotation/FacetsFacetSource.php
+++ b/src/Annotation/FacetsFacetSource.php
@@ -13,7 +13,7 @@ use Drupal\Component\Annotation\Plugin;
  * Defines a Facets facet source annotation.
  *
  * @see \Drupal\facets\FacetSource\FacetSourcePluginManager
- * @see \Drupal\facets\FacetSource\FacetSourceInterface
+ * @see \Drupal\facets\FacetSource\FacetSourcePluginInterface
  * @see \Drupal\facets\FacetSource\FacetSourcePluginBase
  * @see plugin_api
  *
diff --git a/src/Controller/FacetSourceController.php b/src/Controller/FacetSourceController.php
new file mode 100644
index 0000000000000000000000000000000000000000..578e7c9e328dd6d2a27f807c3f2d0dc65f8f59b1
--- /dev/null
+++ b/src/Controller/FacetSourceController.php
@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\facets\Controller\FacetSourceController.
+ */
+
+namespace Drupal\facets\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+
+/**
+ * Provides route responses for facet source configuration.
+ */
+class FacetSourceController extends ControllerBase {
+
+  /**
+   * Configuration for the facet source.
+   *
+   * @param string $source_id
+   *   The plugin id.
+   *
+   * @return array
+   *   A renderable array containing the form.
+   */
+  public function facetSourceConfigForm($source_id) {
+    // Returns the render array of the FacetSourceConfigForm.
+    return $this->formBuilder()->getForm('\Drupal\facets\Form\FacetSourceEditForm');
+  }
+
+}
diff --git a/src/Entity/Facet.php b/src/Entity/Facet.php
index 889a074773f9f8ee4c855e004486826d4bc3078a..88c71bd2c1eb51b292a09b189f33fe437cf3a4b2 100644
--- a/src/Entity/Facet.php
+++ b/src/Entity/Facet.php
@@ -131,7 +131,7 @@ class Facet extends ConfigEntityBase implements FacetInterface {
   /**
    * The facet source belonging to this facet.
    *
-   * @var \Drupal\facets\FacetSource\FacetSourceInterface
+   * @var \Drupal\facets\FacetSource\FacetSourcePluginInterface
    *
    * @see getFacetSource()
    */
@@ -186,6 +186,14 @@ class Facet extends ConfigEntityBase implements FacetInterface {
    */
   protected $widget_plugin_manager;
 
+  /**
+   * The facet source config object.
+   *
+   * @var \Drupal\Facets\FacetSourceInterface
+   *   The facet source config object.
+   */
+  protected $facetSourceConfig;
+
   /**
    * {@inheritdoc}
    */
@@ -370,6 +378,40 @@ class Facet extends ConfigEntityBase implements FacetInterface {
     return $this->facet_source_id;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getFacetSourceConfig() {
+    // Return the facet source config object, if it's already set on the facet.
+    if ($this->facetSourceConfig instanceof FacetSource) {
+      return $this->facetSourceConfig;
+    }
+
+    $storage = \Drupal::entityTypeManager()->getStorage('facets_facet_source');
+    $source_id = str_replace(':', '__', $this->facet_source_id);
+
+    // Load and return the facet source config object from the storage.
+    $facet_source = $storage->load($source_id);
+    if ($facet_source instanceof FacetSource) {
+      $this->facetSourceConfig = $facet_source;
+      return $this->facetSourceConfig;
+    }
+
+    // We didn't have a facet source config entity yet for this facet source
+    // plugin, so we create it on the fly.
+    $facet_source = new FacetSource(
+      [
+        'id' => $source_id,
+        'name' => $this->facet_source_id,
+      ],
+      'facets_facet_source'
+    );
+    $facet_source->save();
+
+    $this->facetSourceConfig = $facet_source;
+    return $this->facetSourceConfig;
+  }
+
   /**
    * Retrieves all processors supported by this facet.
    *
@@ -458,7 +500,7 @@ class Facet extends ConfigEntityBase implements FacetInterface {
           // Create our settings for this facet source..
           $config = isset($this->facetSourcePlugins[$name]) ? $this->facetSourcePlugins[$name] : [];
 
-          /* @var $facet_source \Drupal\facets\FacetSource\FacetSourceInterface */
+          /* @var $facet_source \Drupal\facets\FacetSource\FacetSourcePluginInterface */
           $facet_source = $facet_source_plugin_manager->createInstance($name, $config);
           $this->facetSourcePlugins[$name] = $facet_source;
         }
diff --git a/src/Entity/FacetSource.php b/src/Entity/FacetSource.php
new file mode 100644
index 0000000000000000000000000000000000000000..3d3f7adc7d61c72ef4cee5740bbf47e6fefe5185
--- /dev/null
+++ b/src/Entity/FacetSource.php
@@ -0,0 +1,98 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\facets\Entity\FacetSource.
+ */
+
+namespace Drupal\facets\Entity;
+
+use Drupal\Core\Config\Entity\ConfigEntityBase;
+use Drupal\facets\FacetSourceInterface;
+
+/**
+ * Defines the facet source configuration entity.
+ *
+ * @ConfigEntityType(
+ *   id = "facets_facet_source",
+ *   label = @Translation("Facet source"),
+ *   handlers = {
+ *     "storage" = "Drupal\Core\Config\Entity\ConfigEntityStorage",
+ *     "list_builder" = "Drupal\facets\FacetListBuilder",
+ *     "form" = {
+ *       "default" = "Drupal\facets\Form\FacetSourceEditForm",
+ *       "edit" = "Drupal\facets\Form\FacetSourceEditForm",
+ *       "display" = "Drupal\facets\Form\FacetSourceDisplayForm",
+ *       "delete" = "Drupal\facets\Form\FacetSourceDeleteConfirmForm",
+ *     },
+ *   },
+ *   admin_permission = "administer facets",
+ *   config_prefix = "facet_source",
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "name",
+ *     "uuid" = "uuid"
+ *   },
+ *   config_export = {
+ *     "id",
+ *     "name",
+ *     "filterKey"
+ *   },
+ *   links = {
+ *     "canonical" = "/admin/config/search/facets/facet-sources/",
+ *     "edit-form" = "/admin/config/search/facets/facet-sources/{facets_facet_source}/edit"
+ *   }
+ * )
+ */
+class FacetSource extends ConfigEntityBase implements FacetSourceInterface {
+
+  /**
+   * The ID of the facet source.
+   *
+   * @var string
+   */
+  protected $id;
+
+  /**
+   * A name to be displayed for the facet source.
+   *
+   * @var string
+   */
+  protected $name;
+
+  /**
+   * The key, used for filters in the query string.
+   *
+   * @var string
+   */
+  protected $filterKey;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function id() {
+    return $this->id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return $this->name;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setFilterKey($filter_key) {
+    $this->filterKey = $filter_key;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFilterKey() {
+    return $this->filterKey;
+  }
+
+}
diff --git a/src/FacetInterface.php b/src/FacetInterface.php
index 7e39f2ae90c536438bf9f70af836a6fac6d028b5..58c1cd1ce4739ba933ce0f0af5e961cc08b187b6 100644
--- a/src/FacetInterface.php
+++ b/src/FacetInterface.php
@@ -200,18 +200,26 @@ interface FacetInterface extends ConfigEntityInterface {
   /**
    * Returns the plugin instance of a facet source.
    *
-   * @return \Drupal\facets\FacetSource\FacetSourceInterface
+   * @return \Drupal\facets\FacetSource\FacetSourcePluginInterface
    *   The plugin instance for the facet source.
    */
   public function getFacetSource();
 
+  /**
+   * Returns the facet source configuration object.
+   *
+   * @return \Drupal\facets\FacetSourceInterface
+   *   A facet source configuration object.
+   */
+  public function getFacetSourceConfig();
+
   /**
    * Load the facet sources for this facet.
    *
    * @param bool|TRUE $only_enabled
    *   Only return enabled facet sources.
    *
-   * @return \Drupal\facets\FacetSource\FacetSourceInterface[]
+   * @return \Drupal\facets\FacetSource\FacetSourcePluginInterface[]
    *   An array of facet sources.
    */
   public function getFacetSources($only_enabled = TRUE);
diff --git a/src/FacetListBuilder.php b/src/FacetListBuilder.php
index 3469a797540e4f22d5d222953de121eedc263cb2..bb63d0499734c8446cd969bb2d81ce9f9680c305 100644
--- a/src/FacetListBuilder.php
+++ b/src/FacetListBuilder.php
@@ -10,6 +10,7 @@ namespace Drupal\facets;
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
 use Drupal\Core\Config\Entity\ConfigEntityListBuilder;
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Link;
 
 /**
  * Builds a listing of facet entities.
@@ -134,7 +135,13 @@ class FacetListBuilder extends ConfigEntityListBuilder {
         'status' => array(
           'data' => '',
         ),
-        'operations' => array(),
+        'operations' => array(
+          'data' => Link::createFromRoute(
+            $this->t('Configure'),
+            'entity.facets_facetsource.edit_form',
+            ['source_id' => $facet_source['id']]
+          )->toRenderable(),
+        ),
       ),
       'class' => array('facet-source'),
     );
@@ -153,7 +160,7 @@ class FacetListBuilder extends ConfigEntityListBuilder {
         '#markup' => $this->t(
           'You currently have no facet sources defined. You should start by adding a facet source before creating facets.<br />
            An example of a facet source is a view based on Search API or a Search API page.
-           Other modules can also implement a facet source by providing a plugin that implements the FacetSourceInterface.'
+           Other modules can also implement a facet source by providing a plugin that implements the FacetSourcePluginInterface.'
         ),
       ];
     }
diff --git a/src/FacetManager/DefaultFacetManager.php b/src/FacetManager/DefaultFacetManager.php
index 254ee04047b338a4d23d98cd7fd63ebbcb0121f9..29bd459e62bf5fe615850da2fac514a869463750 100644
--- a/src/FacetManager/DefaultFacetManager.php
+++ b/src/FacetManager/DefaultFacetManager.php
@@ -96,7 +96,7 @@ class DefaultFacetManager {
    *
    * @var string
    *
-   * @see \Drupal\facets\FacetSource\FacetSourceInterface
+   * @see \Drupal\facets\FacetSource\FacetSourcePluginInterface
    */
   protected $facetSourceId;
 
@@ -211,7 +211,7 @@ class DefaultFacetManager {
           $processor_definition = $processor->getPluginDefinition();
           if (is_array($processor_definition['stages']) && array_key_exists(ProcessorInterface::STAGE_PRE_QUERY, $processor_definition['stages'])) {
             /** @var PreQueryProcessorInterface $pre_query_processor */
-            $pre_query_processor = $this->processorPluginManager->createInstance($processor->getPluginDefinition()['id']);
+            $pre_query_processor = $this->processorPluginManager->createInstance($processor->getPluginDefinition()['id'], ['facet' => $facet]);
             if (!$pre_query_processor instanceof PreQueryProcessorInterface) {
               throw new InvalidProcessorException(new FormattableMarkup("The processor @processor has a pre_query definition but doesn't implement the required PreQueryProcessorInterface interface", ['@processor' => $processor_configuration['processor_id']]));
             }
@@ -275,7 +275,7 @@ class DefaultFacetManager {
       $processor_definition = $this->processorPluginManager->getDefinition($processor->getPluginDefinition()['id']);
       if (is_array($processor_definition['stages']) && array_key_exists(ProcessorInterface::STAGE_BUILD, $processor_definition['stages'])) {
         /** @var BuildProcessorInterface $build_processor */
-        $build_processor = $this->processorPluginManager->createInstance($processor->getPluginDefinition()['id']);
+        $build_processor = $this->processorPluginManager->createInstance($processor->getPluginDefinition()['id'], ['facet' => $facet]);
         if (!$build_processor instanceof BuildProcessorInterface) {
           throw new InvalidProcessorException(new FormattableMarkup("The processor @processor has a build definition but doesn't implement the required BuildProcessorInterface interface", ['@processor' => $processor['processor_id']]));
         }
@@ -308,7 +308,7 @@ class DefaultFacetManager {
    */
   public function updateResults() {
     // Get an instance of the facet source.
-    /** @var \drupal\facets\FacetSource\FacetSourceInterface $facet_source_plugin */
+    /** @var \drupal\facets\FacetSource\FacetSourcePluginInterface $facet_source_plugin */
     $facet_source_plugin = $this->facetSourcePluginManager->createInstance($this->facetSourceId);
 
     $facet_source_plugin->fillFacetsWithResults($this->facets);
diff --git a/src/FacetSource/FacetSourcePluginBase.php b/src/FacetSource/FacetSourcePluginBase.php
index 127b72168389d8dfdbc6c8d4aa9ecbd771be90a8..53dba895a863dee2d13c11613c9865c85d5f93e6 100644
--- a/src/FacetSource/FacetSourcePluginBase.php
+++ b/src/FacetSource/FacetSourcePluginBase.php
@@ -23,10 +23,10 @@ use Drupal\Facets\FacetInterface;
  *
  * @see \Drupal\facets\Annotation\FacetsFacetSource
  * @see \Drupal\facets\FacetSource\FacetSourcePluginManager
- * @see \Drupal\facets\FacetSource\FacetSourceInterface
+ * @see \Drupal\facets\FacetSource\FacetSourcePluginInterface
  * @see plugin_api
  */
-abstract class FacetSourcePluginBase extends PluginBase implements FacetSourceInterface, ContainerFactoryPluginInterface {
+abstract class FacetSourcePluginBase extends PluginBase implements FacetSourcePluginInterface, ContainerFactoryPluginInterface {
 
   /**
    * The plugin manager.
diff --git a/src/FacetSource/FacetSourceInterface.php b/src/FacetSource/FacetSourcePluginInterface.php
similarity index 88%
rename from src/FacetSource/FacetSourceInterface.php
rename to src/FacetSource/FacetSourcePluginInterface.php
index aef8c7a6b32e0f7e896d6c3a0b4ee9e4a5ab46ac..93c114ec77717e1e054bc54836b3a12a3c5f3632 100644
--- a/src/FacetSource/FacetSourceInterface.php
+++ b/src/FacetSource/FacetSourcePluginInterface.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains \Drupal\facets\FacetSource\FacetSourceInterface.
+ * Contains \Drupal\facets\FacetSource\FacetSourcePluginInterface.
  */
 
 namespace Drupal\facets\FacetSource;
@@ -15,11 +15,11 @@ use Drupal\facets\FacetInterface;
  *
  * A facet source is used to abstract the data source where facets can be added
  * to. A good example of this is a search api view. There are other possible
- * facet data sources, these all implement the FacetSourceInterface.
+ * facet data sources, these all implement the FacetSourcePluginInterface.
  *
  * @see plugin_api
  */
-interface FacetSourceInterface {
+interface FacetSourcePluginInterface {
 
   /**
    * Adds a configuration form for this facet source.
@@ -30,10 +30,10 @@ interface FacetSourceInterface {
    *   The current form state.
    * @param \Drupal\facets\FacetInterface $facet
    *   The facet being edited.
-   * @param \Drupal\facets\FacetSource\FacetSourceInterface $facet_source
+   * @param \Drupal\facets\FacetSource\FacetSourcePluginInterface $facet_source
    *   The facet source being edited.
    */
-  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourceInterface $facet_source);
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourcePluginInterface $facet_source);
 
   /**
    * Fill in facet data in to the configured facets.
diff --git a/src/FacetSource/FacetSourcePluginManager.php b/src/FacetSource/FacetSourcePluginManager.php
index 377af69dbed363e2d663e650057d1322e18049c6..1b628746ac32798cdcb67be3b1293dcb77cda77e 100644
--- a/src/FacetSource/FacetSourcePluginManager.php
+++ b/src/FacetSource/FacetSourcePluginManager.php
@@ -32,7 +32,7 @@ class FacetSourcePluginManager extends DefaultPluginManager {
    *   The module handler.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/facets/facet_source', $namespaces, $module_handler, 'Drupal\facets\FacetSource\FacetSourceInterface', 'Drupal\facets\Annotation\FacetsFacetSource');
+    parent::__construct('Plugin/facets/facet_source', $namespaces, $module_handler, 'Drupal\facets\FacetSource\FacetSourcePluginInterface', 'Drupal\facets\Annotation\FacetsFacetSource');
   }
 
 }
diff --git a/src/FacetSourceInterface.php b/src/FacetSourceInterface.php
new file mode 100644
index 0000000000000000000000000000000000000000..83957601e43cb07fcf8aafbf67914bd4b1b11740
--- /dev/null
+++ b/src/FacetSourceInterface.php
@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\facets\FacetSourceInterface.
+ */
+
+namespace Drupal\facets;
+
+use Drupal\Core\Config\Entity\ConfigEntityInterface;
+
+/**
+ * The facet source entity.
+ */
+interface FacetSourceInterface extends ConfigEntityInterface {
+
+  /**
+   * Returns the label of the facet source.
+   *
+   * @return string
+   *   The facet name.
+   */
+  public function getName();
+
+  /**
+   * Gets the filter key for this facet source.
+   *
+   * @return string
+   *   The filter key.
+   */
+  public function getFilterKey();
+
+  /**
+   * Sets the filter key for this facet source.
+   *
+   * @param string $filter_key
+   *   The filter key.
+   */
+  public function setFilterKey($filter_key);
+
+}
diff --git a/src/Form/FacetForm.php b/src/Form/FacetForm.php
index fbbf5183ff90e5c2fc2c2f8375f35c4c96a598ee..d16a815d899d88704d5c2dcaed0af363619a87b0 100644
--- a/src/Form/FacetForm.php
+++ b/src/Form/FacetForm.php
@@ -247,7 +247,7 @@ class FacetForm extends EntityForm {
     $facet_source_id = $this->getEntity()->getFacetSourceId();
 
     if (!is_null($facet_source_id) && $facet_source_id !== '') {
-      /** @var \Drupal\facets\FacetSource\FacetSourceInterface $facet_source */
+      /** @var \Drupal\facets\FacetSource\FacetSourcePluginInterface $facet_source */
       $facet_source = $this->getFacetSourcePluginManager()->createInstance($facet_source_id);
 
       if ($config_form = $facet_source->buildConfigurationForm([], $form_state, $this->getEntity(), $facet_source)) {
diff --git a/src/Form/FacetSourceEditForm.php b/src/Form/FacetSourceEditForm.php
new file mode 100644
index 0000000000000000000000000000000000000000..067a39fb05cc556ad0c2795f196580e6340307a8
--- /dev/null
+++ b/src/Form/FacetSourceEditForm.php
@@ -0,0 +1,88 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\facets\Form\FacetSourceEditForm.
+ */
+
+namespace Drupal\facets\Form;
+
+use Drupal\Core\Entity\EntityForm;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\facets\Entity\FacetSource;
+
+/**
+ * Provides a form for editing facet sources.
+ *
+ * Configuration saved trough this form is specific for a facet source and can
+ * be used by all facets on this facet source.
+ */
+class FacetSourceEditForm extends EntityForm {
+
+  /**
+   * Constructs a FacetSourceEditForm.
+   */
+  public function __construct() {
+    $facet_source_storage = \Drupal::entityTypeManager()->getStorage('facets_facet_source');
+
+    // Make sure we remove colons from the source id, those are disallowed in
+    // the entity id.
+    $source_id = $this->getRequest()->get('source_id');
+    $source_id = str_replace(':', '__', $source_id);
+
+    $facet_source = $facet_source_storage->load($source_id);
+
+    if ($facet_source instanceof FacetSource) {
+      $this->setEntity($facet_source);
+    }
+    else {
+
+      // We didn't have a facet source config entity yet for this facet source
+      // plugin, so we create it on the fly.
+      $facet_source = new FacetSource(
+        [
+          'id' => $source_id,
+          'name' => $this->getRequest()->get('source_id'),
+        ],
+        'facets_facet_source'
+      );
+      $facet_source->save();
+      $this->setEntity($facet_source);
+    }
+
+    $this->setModuleHandler(\Drupal::moduleHandler());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'facet_source_edit_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+
+    /** @var \Drupal\facets\FacetSourceInterface $facet_source */
+    $facet_source = $this->getEntity();
+
+    // Filter key setting.
+    $form['filterKey'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Filter key'),
+      '#size' => 20,
+      '#maxlength' => 255,
+      '#default_value' => $facet_source->getFilterKey(),
+      '#description' => $this->t(
+        'The key used in the url to identify the facet source.
+        When using multiple facet sources you should make sure each facet source has a different filter key.'
+      ),
+    ];
+
+    // The parent's form build method will add a save button.
+    return parent::buildForm($form, $form_state);
+  }
+
+}
diff --git a/src/Plugin/facets/facet_source/SearchApiBaseFacetSource.php b/src/Plugin/facets/facet_source/SearchApiBaseFacetSource.php
index b7f86d51ca71f65d1c49908d7ba0720b526359ff..74e98c8991c4015c8c7bb393ed3afca671438ab3 100644
--- a/src/Plugin/facets/facet_source/SearchApiBaseFacetSource.php
+++ b/src/Plugin/facets/facet_source/SearchApiBaseFacetSource.php
@@ -10,10 +10,9 @@ use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\facets\Exception\InvalidQueryTypeException;
 use Drupal\facets\FacetInterface;
+use Drupal\facets\FacetSource\FacetSourcePluginInterface;
 use Drupal\search_api\Backend\BackendInterface;
-use Drupal\facets\FacetSource\FacetSourceInterface;
 use Drupal\facets\FacetSource\FacetSourcePluginBase;
-use Drupal\search_api\FacetsQueryTypeMappingInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -66,7 +65,7 @@ abstract class SearchApiBaseFacetSource extends FacetSourcePluginBase {
   /**
    * {@inheritdoc}
    */
-  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourceInterface $facet_source) {
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state, FacetInterface $facet, FacetSourcePluginInterface $facet_source) {
 
     $form['field_identifier'] = [
       '#type' => 'select',
diff --git a/src/Processor/UrlProcessorPluginBase.php b/src/Processor/UrlProcessorPluginBase.php
index ee8af0b9b3ddbd0ea993191f1bb081866bb9cfe9..99d587592ac983dcca3cadc79875af07301dd6bc 100644
--- a/src/Processor/UrlProcessorPluginBase.php
+++ b/src/Processor/UrlProcessorPluginBase.php
@@ -7,6 +7,7 @@
 namespace Drupal\facets\Processor;
 
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\facets\Exception\InvalidProcessorException;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -53,6 +54,18 @@ abstract class UrlProcessorPluginBase extends ProcessorPluginBase implements Url
   public function __construct(array $configuration, $plugin_id, $plugin_definition, Request $request) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
     $this->request = $request;
+
+    if (!isset($configuration['facet'])) {
+      throw new InvalidProcessorException();
+    }
+
+    /** @var \Drupal\facets\FacetInterface $facet */
+    $facet = $configuration['facet'];
+
+    /** @var \Drupal\facets\FacetSourceInterface $facet_source_config */
+    $facet_source_config = $facet->getFacetSourceConfig();
+
+    $this->filterKey = $facet_source_config->getFilterKey() ?: 'f';
   }
 
   /**
diff --git a/src/Tests/FacetSourceTest.php b/src/Tests/FacetSourceTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..3beef1d33fcaafeb278cf1074bb99e1d794ffd30
--- /dev/null
+++ b/src/Tests/FacetSourceTest.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\facets\Tests\FacetSourceTest.
+ */
+
+namespace Drupal\facets\Tests;
+
+use \Drupal\facets\Tests\WebTestBase as FacetWebTestBase;
+
+/**
+ * Tests the functionality of the facet source config entity.
+ *
+ * @group facets
+ */
+class FacetSourceTest extends FacetWebTestBase {
+
+  /**
+   * Test the facet source editing.
+   */
+  public function testFacetSource() {
+    // Make sure we're logged in with a user that has sufficient permissions.
+    $this->drupalLogin($this->adminUser);
+
+    // Test the overview.
+    $this->drupalGet('admin/config/search/facets');
+    $this->assertLink($this->t('Configure'));
+    $this->clickLink($this->t('Configure'));
+
+    // Test the edit page.
+    $this->assertField('filterKey');
+    $this->drupalPostForm(NULL, array('filterKey' => 'fq'), $this->t('Save'));
+
+    // Test that saving worked.
+    $this->assertField('filterKey');
+    $this->assertRaw('fq');
+  }
+
+}
diff --git a/tests/src/Unit/Plugin/processor/QueryStringUrlProcessorTest.php b/tests/src/Unit/Plugin/processor/QueryStringUrlProcessorTest.php
index 2315ddfef3b0595502f0ae7dd4686788f512525f..d23054b19285ec3533f54687da1796bfdc8cf9d8 100644
--- a/tests/src/Unit/Plugin/processor/QueryStringUrlProcessorTest.php
+++ b/tests/src/Unit/Plugin/processor/QueryStringUrlProcessorTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\Tests\facets\Unit\Plugin\Processor;
 
 use Drupal\facets\Entity\Facet;
+use Drupal\facets\Entity\FacetSource;
 use Drupal\facets\Plugin\facets\processor\QueryStringUrlProcessor;
 use Drupal\facets\Result\Result;
 use Drupal\Tests\UnitTestCase;
@@ -49,6 +50,8 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
       new Result('duck', 'Duck', 15),
       new Result('alpaca', 'Alpaca', 25),
     ];
+
+    $this->setContainer();
   }
 
   /**
@@ -62,7 +65,7 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     $request = new Request();
     $request->query->set('f', ['test:badger']);
 
-    $this->processor = new QueryStringUrlProcessor([], 'query_string', [], $request);
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
     $this->processor->preQuery($facet);
 
     $this->assertEquals(['badger'], $facet->getActiveItems());
@@ -79,7 +82,7 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     $request = new Request();
     $request->query->set('f', ['test:badger', 'test:mushroom', 'donkey:kong']);
 
-    $this->processor = new QueryStringUrlProcessor([], 'query_string', [], $request);
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
     $this->processor->preQuery($facet);
 
     $this->assertEquals(['badger', 'mushroom'], $facet->getActiveItems());
@@ -95,7 +98,7 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     $request = new Request();
     $request->query->set('f', []);
 
-    $this->processor = new QueryStringUrlProcessor([], 'query_string', [], $request);
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
     $results = $this->processor->build($facet, []);
     $this->assertEmpty($results);
   }
@@ -111,9 +114,7 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     $request = new Request();
     $request->query->set('f', []);
 
-    $this->setContainer();
-
-    $this->processor = new QueryStringUrlProcessor([], 'query_string', [], $request);
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
     $results = $this->processor->build($facet, $this->originalResults);
 
     /** @var \Drupal\facets\Result\ResultInterface $r */
@@ -137,9 +138,7 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     $request = new Request();
     $request->query->set('f', ['king:kong']);
 
-    $this->setContainer();
-
-    $this->processor = new QueryStringUrlProcessor([], 'query_string', [], $request);
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
     $results = $this->processor->build($facet, $original_results);
 
     /** @var \Drupal\facets\Result\ResultInterface $r */
@@ -154,6 +153,46 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
     }
   }
 
+  /**
+   * Test that the facet source configuration filter key override works.
+   */
+  public function testFacetSourceFilterKeyOverride() {
+    $facet_source = new FacetSource(['filterKey' => 'ab'], 'facets_facet_source');
+
+    // Override the container with the new facet source.
+    $storage = $this->getMock('\Drupal\Core\Entity\EntityStorageInterface');
+    $storage->expects($this->once())
+      ->method('load')
+      ->willReturn($facet_source);
+    $em = $this->getMockBuilder('\Drupal\Core\Entity\EntityTypeManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $em->expects($this->any())
+      ->method('getStorage')
+      ->willReturn($storage);
+
+    $container = \Drupal::getContainer();
+    $container->set('entity_type.manager', $em);
+    \Drupal::setContainer($container);
+
+    $facet = new Facet([], 'facet');
+    $facet->setFieldIdentifier('test');
+    $facet->setFacetSourceId('facet_source__dummy');
+
+    $request = new Request();
+    $request->query->set('ab', []);
+
+    $this->processor = new QueryStringUrlProcessor(['facet' => $facet], 'query_string', [], $request);
+    $results = $this->processor->build($facet, $this->originalResults);
+
+    /** @var \Drupal\facets\Result\ResultInterface $r */
+    foreach ($results as $r) {
+      $this->assertInstanceOf('\Drupal\facets\Result\ResultInterface', $r);
+      $this->assertEquals('route:test?ab[0]=test%3A' . $r->getRawValue(), $r->getUrl()->toUriString());
+    }
+
+  }
+
   /**
    * Set the container for use in unit tests.
    */
@@ -170,21 +209,31 @@ class QueryStringUrlProcessorTest extends UnitTestCase {
         ]
       );
 
-    $fsi = $this->getMockBuilder('\Drupal\facets\FacetSource\FacetSourceInterface')
+    $fsi = $this->getMockBuilder('\Drupal\facets\FacetSource\FacetSourcePluginInterface')
       ->disableOriginalConstructor()
       ->getMock();
     $fsi->method('getPath')
       ->willReturn('search/test');
 
-    $manager = $this->getMockBuilder('Drupal\facets\FacetSource\FacetSourcePluginManager')
+    $manager = $this->getMockBuilder('\Drupal\facets\FacetSource\FacetSourcePluginManager')
       ->disableOriginalConstructor()
       ->getMock();
     $manager->method('createInstance')
       ->willReturn($fsi);
 
+    $storage = $this->getMock('\Drupal\Core\Entity\EntityStorageInterface');
+    $em = $this->getMockBuilder('\Drupal\Core\Entity\EntityTypeManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $em->expects($this->any())
+      ->method('getStorage')
+      ->willReturn($storage);
+
     $container = new ContainerBuilder();
     $container->set('router.no_access_checks', $router);
     $container->set('plugin.manager.facets.facet_source', $manager);
+    $container->set('entity_type.manager', $em);
+    $container->set('entity.manager', $em);
     \Drupal::setContainer($container);
   }