zulip/docs/development/using.md

Using the Development Environment

Once the development environment is running, you can visit http://localhost:9991/ in your browser. By default, the development server homepage just shows a list of the users that exist on the server and you can login as any of them by just clicking on a user. This setup saves time for the common case where you want to test something other than the login process; to test the login process you'll want to change AUTHENTICATION_BACKENDS in the not-PRODUCTION case of zproject/settings.py from zproject.backends.DevAuthBackend to use the auth method(s) you'd like to test.

While developing, it's helpful to watch the run-dev.py console output, which will show any errors your Zulip development server encounters.

To manually query the Postgres database, run psql zulip for an interactive console.

When you make a change, here's a guide for what you need to do in order to see your change take effect in Development:

• If you change CSS files, your changes will appear immediately via hot module replacement. If you change JavaScript or Handlebars templates, the browser window will be reloaded automatically. For Jinja2 backend templates, you'll need to reload the browser manually to see changes take effect.

• If you change Python code used by the main Django/Tornado server processes, these services are run on top of Django's manage.py runserver which will automatically restart the Zulip Django and Tornado servers whenever you save changes to Python code. You can watch this happen in the run-dev.py console to make sure the backend has reloaded.

• The Python queue workers will also automatically restart when you save changes. However, you may need to ctrl-C and then restart run-dev.py manually if a queue worker has crashed.

• If you change the database schema, you'll need to use the standard Django migrations process to create and then run your migrations; see the new feature tutorial for an example. Additionally you should check out the detailed testing docs for how to run the tests properly after doing a migration.

(In production, everything runs under supervisord and thus will restart if it crashes, and upgrade-zulip will take care of running migrations and then cleanly restaring the server for you).