Merge branch 'master' into pipeline-ui-updatespipeline-ui-updates

* master: (259 commits)
  Exclude non existent repository storages.
  fixed minor animation glitch in mini pipeline graph animation
  Update Bitbucket callback URL documentation
  Update build step for KaTeX.
  Add KaTeX fonts to assets paths and precompile
  Replace url('...') to url(font-path('...'))
  Rname katex.css to katex.scss
  Revert conflicting EE changes
  Added Autodeploy script for OpenShift
  Whitelist next project names: notes, services
  Put back progress bar CSS
  Remove unneeded bundle refs.
  Adds entry to changelog
  Reduce MR widget title by one pixel
  Use same font size for all items in issue title
  Adds background color for disabled state to merge when succeeds dropdown
  Filter protocol-relative URLs in ExternalLinkFilter. Fixes issue #22742.
  Move javascript for widget check to ci_bundle.
  Introduce "Set up autodeploy" button to help configure GitLab CI for deployment
  Whitelist next project names: help, ci, admin, search
  ...

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+# Web terminals
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7690)
+in GitLab 8.15. Only project masters and owners can access web terminals.
+
+With the introduction of the [Kubernetes](../../project_services/kubernetes.md)
+project service, GitLab gained the ability to store and use credentials for a
+Kubernetes cluster. One of the things it uses these credentials for is providing
+access to [web terminals](../../ci/environments.html#web-terminals)
+for environments.
+
+## How it works
+
+A detailed overview of the architecture of web terminals and how they work
+can be found in [this document](https://gitlab.com/gitlab-org/gitlab-workhorse/blob/master/doc/terminal.md).
+In brief:
+
+* GitLab relies on the user to provide their own Kubernetes credentials, and to
+  appropriately label the pods they create when deploying.
+* When a user navigates to the terminal page for an environment, they are served
+  a JavaScript application that opens a WebSocket connection back to GitLab.
+* The WebSocket is handled in [Workhorse](https://gitlab.com/gitlab-org/gitlab-workhorse),
+   rather than the Rails application server.
+* Workhorse queries Rails for connection details and user permissions; Rails
+  queries Kubernetes for them in the background, using [Sidekiq](../troubleshooting/sidekiq.md)
+* Workhorse acts as a proxy server between the user's browser and the Kubernetes
+  API, passing WebSocket frames between the two.
+* Workhorse regularly polls Rails, terminating the WebSocket connection if the
+  user no longer has permission to access the terminal, or if the connection
+  details have changed.
+
+##  Enabling and disabling terminal support
+
+As web terminals use WebSockets, every HTTP/HTTPS reverse proxy in front of
+Workhorse needs to be configured to pass the `Connection` and `Upgrade` headers
+through to the next one in the chain. If you installed Gitlab using Omnibus, or
+from source, starting with GitLab 8.15, this should be done by the default
+configuration, so there's no need for you to do anything.
+
+However, if you run a [load balancer](../high_availability/load_balancer.md) in
+front of GitLab, you may need to make some changes to your configuration. These
+guides document the necessary steps for a selection of popular reverse proxies:
+
+* [Apache](https://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html)
+* [NGINX](https://www.nginx.com/blog/websocket-nginx/)
+* [HAProxy](http://blog.haproxy.com/2012/11/07/websockets-load-balancing-with-haproxy/)
+* [Varnish](https://www.varnish-cache.org/docs/4.1/users-guide/vcl-example-websockets.html)
+
+Workhorse won't let WebSocket requests through to non-WebSocket endpoints, so
+it's safe to enable support for these headers globally. If you'd rather had a
+narrower set of rules, you can restrict it to URLs ending with `/terminal.ws`
+(although this may still have a few false positives).
+
+If you installed from source, or have made any configuration changes to your
+Omnibus installation before upgrading to 8.15, you may need to make some
+changes to your configuration. See the  [8.14 to 8.15 upgrade](../../update/8.14-to-8.15.md#nginx-configuration)
+document for more details.
+
+If you'd like to disable web terminal support in GitLab, just stop passing
+the `Connection` and `Upgrade` hop-by-hop headers in the *first* HTTP reverse
+proxy in the chain. For most users, this will be the NGINX server bundled with
+Omnibus Gitlab, in which case, you need to:
+
+* Find the `nginx['proxy_set_headers']` section of your `gitlab.rb` file
+* Ensure the whole block is uncommented, and then comment out or remove the
+  `Connection` and `Upgrade` lines.
+
+For your own load balancer, just reverse the configuration changes recommended
+by the above guides.
+
+When these headers are not passed through, Workhorse will return a
+`400 Bad Request` response to users attempting to use a web terminal. In turn,
+they will receive a `Connection failed` message.