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---
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stage: Create
group: Ecosystem
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
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---
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# Web terminals
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> [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/7690) in GitLab 8.15.
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With the introduction of the [Kubernetes integration ](../../user/project/clusters/index.md ),
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GitLab can store and use credentials for a Kubernetes cluster.
GitLab uses these credentials to provide access to
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[web terminals ](../../ci/environments/index.md#web-terminals ) for environments.
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NOTE:
Only project maintainers and owners can access web terminals.
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## How it works
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/channel.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
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
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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
details have changed.
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## Security
GitLab and [GitLab Runner ](https://docs.gitlab.com/runner/ ) take some
precautions to keep interactive web terminal data encrypted between them, and
everything protected with authorization guards. This is described in more
detail below.
- Interactive web terminals are completely disabled unless [`[session_server]`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-session_server-section) is configured.
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- Every time the runner starts, it generates an `x509` certificate that is used for a `wss` (Web Socket Secure) connection.
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- For every created job, a random URL is generated which is discarded at the end of the job. This URL is used to establish a web socket connection. The URL for the session is in the format `(IP|HOST):PORT/session/$SOME_HASH` , where the `IP/HOST` and `PORT` are the configured [`listen_address` ](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-session_server-section ).
- Every session URL that is created has an authorization header that needs to be sent, to establish a `wss` connection.
- The session URL is not exposed to the users in any way. GitLab holds all the state internally and proxies accordingly.
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## Enabling and disabling terminal support
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NOTE:
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AWS Elastic Load Balancers (ELBs) do not support web sockets.
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If you want web terminals to work, use AWS Application Load Balancers (ALBs).
Read [AWS Elastic Load Balancing Product Comparison ](https://aws.amazon.com/elasticloadbalancing/features/#compare )
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for more information.
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As web terminals use WebSockets, every HTTP/HTTPS reverse proxy in front of
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Workhorse must be configured to pass the `Connection` and `Upgrade` headers
to the next one in the chain. GitLab is configured by default to do so.
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However, if you run a [load balancer ](../load_balancer.md ) in
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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:
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- [Apache ](https://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html )
- [NGINX ](https://www.nginx.com/blog/websocket-nginx/ )
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- [HAProxy ](https://www.haproxy.com/blog/websockets-load-balancing-with-haproxy/ )
- [Varnish ](https://varnish-cache.org/docs/4.1/users-guide/vcl-example-websockets.html )
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Workhorse doesn'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 prefer a
narrower set of rules, you can restrict it to URLs ending with `/terminal.ws` .
This approach may still result in 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 changes
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to your configuration. Read
[Upgrading Community Edition and Enterprise Edition from source ](../../update/upgrading_from_source.md#nginx-configuration )
for more details.
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To disable web terminal support in GitLab, 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 is 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
- Ensure the whole block is uncommented, and then comment out or remove the
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`Connection` and `Upgrade` lines.
For your own load balancer, just reverse the configuration changes recommended
by the above guides.
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When these headers are not passed through, Workhorse returns a
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`400 Bad Request` response to users attempting to use a web terminal. In turn,
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they receive a `Connection failed` message.
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## Limiting WebSocket connection time
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> [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/8413) in GitLab 8.17.
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Terminal sessions, by default, do not expire.
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You can limit terminal session lifetime in your GitLab instance. To do so,
go to [**Admin Area > Settings > Web terminal** ](../../user/admin_area/settings/index.md#general ),
and set a `max session time` .