82 lines
4.2 KiB
Markdown
82 lines
4.2 KiB
Markdown
# Web terminals
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> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7690)
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in GitLab 8.15. Only project maintainers and owners can access web terminals.
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With the introduction of the [Kubernetes integration](../../user/project/clusters/index.md),
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GitLab gained the ability to store and use credentials for a Kubernetes cluster.
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One of the things it uses these credentials for is providing access to
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[web terminals](../../ci/environments.md#web-terminals) for environments.
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## How it works
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A detailed overview of the architecture of web terminals and how they work
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can be found in [this document](https://gitlab.com/gitlab-org/gitlab-workhorse/blob/master/doc/terminal.md).
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In brief:
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* GitLab relies on the user to provide their own Kubernetes credentials, and to
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appropriately label the pods they create when deploying.
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* When a user navigates to the terminal page for an environment, they are served
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a JavaScript application that opens a WebSocket connection back to GitLab.
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* The WebSocket is handled in [Workhorse](https://gitlab.com/gitlab-org/gitlab-workhorse),
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rather than the Rails application server.
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* Workhorse queries Rails for connection details and user permissions; Rails
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queries Kubernetes for them in the background, using [Sidekiq](../troubleshooting/sidekiq.md)
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* Workhorse acts as a proxy server between the user's browser and the Kubernetes
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API, passing WebSocket frames between the two.
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* Workhorse regularly polls Rails, terminating the WebSocket connection if the
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user no longer has permission to access the terminal, or if the connection
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details have changed.
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## Enabling and disabling terminal support
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As web terminals use WebSockets, every HTTP/HTTPS reverse proxy in front of
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Workhorse needs to be configured to pass the `Connection` and `Upgrade` headers
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through to the next one in the chain. If you installed GitLab using Omnibus, or
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from source, starting with GitLab 8.15, this should be done by the default
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configuration, so there's no need for you to do anything.
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However, if you run a [load balancer](../high_availability/load_balancer.md) in
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front of GitLab, you may need to make some changes to your configuration. These
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guides document the necessary steps for a selection of popular reverse proxies:
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* [Apache](https://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html)
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* [NGINX](https://www.nginx.com/blog/websocket-nginx/)
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* [HAProxy](http://blog.haproxy.com/2012/11/07/websockets-load-balancing-with-haproxy/)
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* [Varnish](https://www.varnish-cache.org/docs/4.1/users-guide/vcl-example-websockets.html)
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Workhorse won't let WebSocket requests through to non-WebSocket endpoints, so
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it's safe to enable support for these headers globally. If you'd rather had a
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narrower set of rules, you can restrict it to URLs ending with `/terminal.ws`
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(although this may still have a few false positives).
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If you installed from source, or have made any configuration changes to your
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Omnibus installation before upgrading to 8.15, you may need to make some
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changes to your configuration. See the [8.14 to 8.15 upgrade](../../update/8.14-to-8.15.md#nginx-configuration)
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document for more details.
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If you'd like to disable web terminal support in GitLab, just stop passing
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the `Connection` and `Upgrade` hop-by-hop headers in the *first* HTTP reverse
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proxy in the chain. For most users, this will be the NGINX server bundled with
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Omnibus GitLab, in which case, you need to:
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* Find the `nginx['proxy_set_headers']` section of your `gitlab.rb` file
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* Ensure the whole block is uncommented, and then comment out or remove the
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`Connection` and `Upgrade` lines.
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For your own load balancer, just reverse the configuration changes recommended
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by the above guides.
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When these headers are not passed through, Workhorse will return a
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`400 Bad Request` response to users attempting to use a web terminal. In turn,
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they will receive a `Connection failed` message.
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## Limiting WebSocket connection time
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> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8413)
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in GitLab 8.17.
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Terminal sessions use long-lived connections; by default, these may last
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forever. You can configure a maximum session time in the Admin area of your
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GitLab instance if you find this undesirable from a scalability or security
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point of view.
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