zulip/docs/production/multiple-organizations.md

Hosting multiple organizations

The vast majority of Zulip servers host just a single organization (or "realm", as the Zulip code calls organizations). This article documents what's involved in hosting multiple Zulip organizations on a single server.

Throughout this article, we'll assume you're working on a zulip server with hostname zulip.example.com. You may also find the more technically focused article on realms to be useful reading.

Subdomains

Zulip's approach for supporting multiple organizations on a single Zulip server is for each organization to be hosted on its own subdomain. E.g. you'd have org1.zulip.example.com and org2.zulip.example.com.

Web security standards mean that one subdomain per organization is required to support a use logging into multiple organizations on a server at the same time.

When you want to create a new organization, you need to do a few things:

• If you're using Zulip older than 1.7, you'll need to set REALMS_HAVE_SUBDOMAINS=True in your /etc/zulip/settings.py file. That setting is the default in 1.7 and later.
• Make sure you have SSL certificates for all of the subdomains you're going to use. If you're using our LetsEncrypt instructions, it's easy to just specify multiple subdomains in your certificate request.
• If necessary, modify your nginx configuration to use your new certificates.
• Use ./manage.py generate_realm_creation_link again to create your new organization. Review the install instructions if you need a refresher on how this works.

For servers hosting a large number of organizations, like zulipchat.com, one can set ROOT_DOMAIN_LANDING_PAGE = True in /etc/zulip/settings.py so that the homepage for the server is a copy of the Zulip homepage.

The root domain

Most Zulip servers host a single Zulip organization on the root domain (i.e. zulip.example.com). The way this is implemented internally involves the organization having the empty string ('') as its "subdomain". You can mix having an organization on the root domain and some others on subdomains (e.g. it.zulip.example.com).

The system bot realm

This is very much an implementation detail, but worth documenting to avoid confusion as to why there's an extra realm when inspecting the Zulip database.

Every Zulip server comes with 1 realm that isn't created by users: the zulip realm. By default, this realm only contains the Zulip "system bots". You can get a list of these on your system via ./scripts/get-django-setting INTERNAL_BOTS, but this is where bots like "Notification Bot", "Welcome Bot", etc. exist. In the future, we're considering moving these bots to exist in every realm, so that we wouldn't need the system realm anymore.