1 files changed, 56 insertions, 0 deletions
diff --git a/app/channels/graphql_channel.rb b/app/channels/graphql_channel.rb
new file mode 100644
index 00000000000..d364cc2b64b
--- /dev/null
+++ b/app/channels/graphql_channel.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+# This is based on https://github.com/rmosolgo/graphql-ruby/blob/v1.11.8/lib/graphql/subscriptions/action_cable_subscriptions.rb#L19-L82
+# modified to work with our own ActionCableLink client
+
+class GraphqlChannel < ApplicationCable::Channel # rubocop:disable Gitlab/NamespacedClass
+  def subscribed
+    @subscription_ids = []
+
+    query = params['query']
+    variables = Gitlab::Graphql::Variables.new(params['variables']).to_h
+    operation_name = params['operationName']
+
+    result = GitlabSchema.execute(
+      query,
+      context: context,
+      variables: variables,
+      operation_name: operation_name
+    )
+
+    payload = {
+      result: result.to_h,
+      more: result.subscription?
+    }
+
+    # Track the subscription here so we can remove it
+    # on unsubscribe.
+    if result.context[:subscription_id]
+      @subscription_ids << result.context[:subscription_id]
+    end
+
+    transmit(payload)
+  end
+
+  def unsubscribed
+    @subscription_ids.each do |sid|
+      GitlabSchema.subscriptions.delete_subscription(sid)
+    end
+  end
+
+  rescue_from Gitlab::Graphql::Variables::Invalid do |exception|
+    transmit({ errors: [{ message: exception.message }] })
+  end
+
+  private
+
+  # When modifying the context, also update GraphqlController#context if needed
+  # so that we have similar context when executing queries, mutations, and subscriptions
+  #
+  # Objects added to the context may also need to be reloaded in
+  # `Subscriptions::BaseSubscription` so that they are not stale
+  def context
+    # is_sessionless_user is always false because we only support cookie auth in ActionCable
+    { channel: self, current_user: current_user, is_sessionless_user: false }
+  end
+end