gitlab-org--gitlab-foss/doc/administration/high_availability/load_balancer.md

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# Load Balancer for GitLab HA
In an active/active GitLab configuration, you will need a load balancer to route
traffic to the application servers. The specifics on which load balancer to use
or the exact configuration is beyond the scope of GitLab documentation. We hope
that if you're managing HA systems like GitLab you have a load balancer of
choice already. Some examples including HAProxy (open-source), F5 Big-IP LTM,
and Citrix Net Scaler. This documentation will outline what ports and protocols
you need to use with GitLab.
## Basic ports
| LB Port | Backend Port | Protocol |
| ------- | ------------ | --------------- |
| 80 | 80 | HTTP [^1] |
| 443 | 443 | TCP or HTTPS [^1] [^2] |
| 22 | 22 | TCP |
## GitLab Pages Ports
If you're using GitLab Pages with custom domain support you will need some
additional port configurations.
GitLab Pages requires a separate virtual IP address. Configure DNS to point the
`pages_external_url` from `/etc/gitlab/gitlab.rb` at the new virtual IP address. See the
[GitLab Pages documentation][gitlab-pages] for more information.
| LB Port | Backend Port | Protocol |
| ------- | ------------ | -------- |
| 80 | Varies [^3] | HTTP |
| 443 | Varies [^3] | TCP [^4] |
## Alternate SSH Port
Some organizations have policies against opening SSH port 22. In this case,
it may be helpful to configure an alternate SSH hostname that allows users
to use SSH on port 443. An alternate SSH hostname will require a new virtual IP address
compared to the other GitLab HTTP configuration above.
Configure DNS for an alternate SSH hostname such as altssh.gitlab.example.com.
| LB Port | Backend Port | Protocol |
| ------- | ------------ | -------- |
| 443 | 22 | TCP |
---
Read more on high-availability configuration:
1. [Configure the database](database.md)
1. [Configure Redis](redis.md)
1. [Configure NFS](nfs.md)
1. [Configure the GitLab application servers](gitlab.md)
[^1]: [Web terminal](../../ci/environments.md#web-terminals) support requires
your load balancer to correctly handle WebSocket connections. When using
HTTP or HTTPS proxying, this means your load balancer must be configured
to pass through the `Connection` and `Upgrade` hop-by-hop headers. See the
[web terminal](../integration/terminal.md) integration guide for
more details.
[^2]: When using HTTPS protocol for port 443, you will need to add an SSL
certificate to the load balancers. If you wish to terminate SSL at the
GitLab application server instead, use TCP protocol.
[^3]: The backend port for GitLab Pages depends on the
`gitlab_pages['external_http']` and `gitlab_pages['external_https']`
setting. See [GitLab Pages documentation][gitlab-pages] for more details.
[^4]: Port 443 for GitLab Pages should always use the TCP protocol. Users can
configure custom domains with custom SSL, which would not be possible
if SSL was terminated at the load balancer.
[gitlab-pages]: ../pages/index.md