zulip/docs/settings.md

Settings system

The page documents the Zulip settings system, and hopefully should help you decide how to correctly implement new settings you're adding to Zulip. We have two types of administrative settings in Zulip: server settings (which are set via configuration files are apply to the whole Zulip installation), and realm settings (which are usually set via the /#administration page in the Zulip web application) and apply to a single Zulip realm/organization (which for most Zulip servers is the only realm on the server).

Server settings

Zulip uses the Django settings system, which means that the settings files are Python programs that set a lot of variables with all-capital names like EMAIL_GATEWAY_PATTERN. You can access these anywhere in the Zulip Django code using e.g.:

from django.conf import settings
print(settings.EMAIL_GATEWAY_PATTERN)

Additionally, if you need to access a Django setting in a shell script (or just on the command line for debugging), you can use e.g.:

$ ./scripts/get-django-setting EMAIL_GATEWAY_PATTERN
%s@localhost:9991

Zulip has separated those settings that we expect a system administrator to change (with nice documentation) from the ~1000 lines of settings needed by the Zulip Django app. As a result, there are a few files involved in the Zulip settings for server administrations. In a production environment, we have:

• /etc/zulip/settings.py (generated from zproject/prod_settings_template.py) is the main system administration facing settings file for Zulip. It contains all the server-specific settings, such as how to send outgoing email, the hostname of the Postgres database, etc., but does not contain any secrets (e.g. passwords, secret API keys, cryptographic keys, etc.). The way we generally do settings that can be controlled with shell access to a Zulip server is to put a default in zproject/settings.py, and then override it here.

• /etc/zulip/zulip-secrets.conf (generated by scripts/setup/generate-secrets.py as part of installation) contains secrets used by the Zulip installation. These are read using the standard Python ConfigParser, and accessed in zproject/settings.py by the get_secret function.

• zproject/settings.py is the main Django settings file for Zulip. It contains all the settings that are constant for all Zulip installations (e.g. configuration for logging, static assets, middleware, etc.), as well as default values for the settings the user would set in /etc/zulip/settings.py (you can look at the DEFAULT_SETTINGS dictionary to easily review the settings available). zproject/settings.py has a line from prod_settings import *, which has the effect of importing /etc/zulip/settings.py in a prod environment (via a symlink).

In a development environment, we have zproject/settings.py, and additionally:

• zproject/dev_settings.py has the settings for the Zulip development environment; it mostly just imports prod_settings_template.py.

• zproject/dev-secrets.conf replaces /etc/zulip/zulip-secrets.conf.

• zproject/test_settings.py has the (default) settings used for the Zulip tests (both backend and Casper), which are applied on top of the development environment settings.

When adding a new server setting to Zulip, you will typically add it in two or three places:

• In DEFAULT_SETTINGS in zproject/settings.py, with a default value for production environments.

• In an appropriate section of zproject/prod_settings_template.py, with documentation in the comments explaining the settings's purpose and effect.

• Possibly also zproject/dev_settings.py, if the desired value of the setting for Zulip development environments is different from the default for production (and similarly for zproject/test_settings.py).

Most settings should be enabled in the development environment, to maximize convenience of testing all of Zulip's features; they should be enabled by default in production if we expect most Zulip sites to want those settings.

Testing non-default settings

You can write tests for settings using e.g. with self.settings(GOOGLE_CLIENT_ID=None). However, this only works for settings which are checked at runtime, not settings which are only accessed in initialization of Django (or Zulip) internals (e.g. DATABASES). See the Django docs on overriding settings in tests for more details.

Realm settings

Realm settings are preferred for any configuration that is a matter of organizational policy (as opposed to technical capabilities of the server). As a result, configuration options for user-facing functionality is almost always added as a new realm setting, not a server setting. The new feature tutorial documents the process for adding a new realm setting to Zulip.

So for example, the following server settings will eventually be replaced with realm settings:

• NAME_CHANGES_DISABLED
• INLINE_IMAGE_PREVIEW
• ENABLE_GRAVATAR
• Which authentication methods are allowed should probably appear in both places; in server settings indicating the capabilities of the server, and in the realm settings indicating which methods the realm administrator wants to allow users to login with.