Allow admins to select which groups to replicate per Geo node

app/views/admin/geo_nodes/_form.html.haml

@@ -21,3 +21,11 @@
         %p.help-block
           Paste a machine public key here for the GitLab user this node runs on. Read more about how to generate it
           = link_to "here", help_page_path("ssh/README")
+
+- if geo_node.persisted? && geo_node.secondary?
+  .form-group
+    = form.label :group_ids, 'Groups to replicate', class: 'control-label'
+    .col-sm-10
+      = form.select :group_ids, namespaces_options(geo_node.group_ids), { include_hidden: false }, multiple: true, class: 'select2 select-wide', data: { field: 'group_ids' }
+      .help-block
+        Choose which groups you wish to replicate.

app/views/admin/geo_nodes/index.html.haml

@@ -33,6 +33,12 @@
               %span.help-block Primary node
             - else
               = status_loading_icon
+              - if node.groups.any?
+                %p
+                  %span.help-block
+                    Groups to replicate:
+                    %strong.node-info
+                      = node_selected_groups_to_replicate(node)
               .js-geo-node-status{ style: 'display: none' }
                 - if node.enabled?
                   %p

ee/app/controllers/admin/geo_nodes_controller.rb

@@ -79,7 +79,7 @@ class Admin::GeoNodesController < Admin::ApplicationController
   private
 
   def geo_node_params
-    params.require(:geo_node).permit(:url, :primary, geo_node_key_attributes: [:key])
+    params.require(:geo_node).permit(:url, :primary, group_ids: [], geo_node_key_attributes: [:key])
   end
 
   def check_license

ee/app/helpers/ee/geo_helper.rb

 module EE
   module GeoHelper
+    def node_selected_groups_to_replicate(node)
+      node.groups.sort_by(&:human_name).map(&:human_name).join(', ')
+    end
+
     def node_status_icon(node)
       unless node.primary?
         status = node.enabled? ? 'unknown' : 'disabled'