From d4f6e1f21c40c729d5ed3a3f02d6a84777a40163 Mon Sep 17 00:00:00 2001
From: blackst0ne <blackst0ne.ru@gmail.com>
Date: Wed, 20 Jun 2018 14:18:16 +1100
Subject: [PATCH] [Rails5] Fix ActionCable '/cable' mountpoint conflict

Since Rails 5.0 the new framework has been added. It's called ActionCable.
It brings WebSockets support to rails applications.
By default the mountpoint of WebSocket requests is `/cable` [1].

GitLab allows using top level names as namespaces or usernames.
For example, `gitlab.com/cable` at this moment leads to a user with the
nickname `cable`.

This commit changes ActionCable's mountpoint to a reserved top level
word `-`.
This is just a stub and should not be be used in real work.

Please set correct mountpoints for each environments when configuring
ActionCable for real using.

[1]: https://github.com/rails/rails/blob/5-0-stable/actioncable/lib/action_cable.rb#L38
---
 ...uld-cause-conflicts-with-existing-namespaced-routes.yml | 5 +++++
 config/application.rb                                      | 7 +++++++
 2 files changed, 12 insertions(+)
 create mode 100644 changelogs/unreleased/blackst0ne-rails5-found-new-routes-that-could-cause-conflicts-with-existing-namespaced-routes.yml

diff --git a/changelogs/unreleased/blackst0ne-rails5-found-new-routes-that-could-cause-conflicts-with-existing-namespaced-routes.yml b/changelogs/unreleased/blackst0ne-rails5-found-new-routes-that-could-cause-conflicts-with-existing-namespaced-routes.yml
new file mode 100644
index 00000000000..c8d916af824
--- /dev/null
+++ b/changelogs/unreleased/blackst0ne-rails5-found-new-routes-that-could-cause-conflicts-with-existing-namespaced-routes.yml
@@ -0,0 +1,5 @@
+---
+title: "[Rails5] Fix ActionCable '/cable' mountpoint conflict"
+merge_request: 20015
+author: "@blackst0ne"
+type: fixed
diff --git a/config/application.rb b/config/application.rb
index 95f6d2c9af1..385eb65e7f4 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -57,6 +57,13 @@ module Gitlab
     # Configure the default encoding used in templates for Ruby 1.9.
     config.encoding = "utf-8"
 
+    # ActionCable mount point.
+    # The default Rails' mount point is `/cable` which may conflict with existing
+    # namespaces/users.
+    # https://github.com/rails/rails/blob/5-0-stable/actioncable/lib/action_cable.rb#L38
+    # Please change this value when configuring ActionCable for real usage.
+    config.action_cable.mount_path = "-" if rails5?
+
     # Configure sensitive parameters which will be filtered from the log file.
     #
     # Parameters filtered: