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You are reading a development version of the Zulip documentation. These instructions may not correspond to the latest Zulip Server release. See documentation for the latest stable release.

Maintain, secure, and upgrade

This page covers topics that will help you maintain a healthy, up-to-date, and secure Zulip installation, including:

You may also want to read this related content:

Monitoring

The complete Nagios configuration (sans secret keys) used to monitor zulip.com is available under puppet/zulip_ops in the Zulip Git repository (those files are not installed in the release tarballs).

The Nagios plugins used by that configuration are installed automatically by the Zulip installation process in subdirectories under /usr/lib/nagios/plugins/. The following is a summary of the various Nagios plugins included with Zulip and what they check:

Application server and queue worker monitoring:

  • check_send_receive_time (sends a test message through the system between two bot users to check that end-to-end message sending works)

  • check_rabbitmq_consumers and check_rabbitmq_queues (checks for rabbitmq being down or the queue workers being behind)

  • check_queue_worker_errors (checks for errors reported by the queue workers)

  • check_worker_memory (monitors for memory leaks in queue workers)

  • check_email_deliverer_backlog and check_email_deliverer_process (monitors for whether scheduled outgoing emails are being sent)

Database monitoring:

  • check_postgres_replication_lag (checks streaming replication is up to date).

  • check_postgres (checks the health of the postgres database)

  • check_postgres_backup (checks backups are up to date; see above)

  • check_fts_update_log (monitors for whether full-text search updates are being processed)

Standard server monitoring:

  • check_website_response.sh (standard HTTP check)

  • check_debian_packages (checks apt repository is up to date)

Note: While most commands require no special permissions, check_email_deliverer_backlog, requires the nagios user to be in the zulip group, in order to access SECRET_KEY and thus run Zulip management commands.

If you’re using these plugins, bug reports and pull requests to make it easier to monitor Zulip and maintain it in production are encouraged!

Scalability

This section attempts to address the considerations involved with running Zulip with larger teams (especially >1000 users).

  • For an organization with 100+ users, it’s important to have more than 4GB of RAM on the system. Zulip will install on a system with 2GB of RAM, but with less than 3.5GB of RAM, it will run its queue processors multithreaded to conserve memory; this creates a significant performance bottleneck.

  • chat.zulip.org, with thousands of user accounts and thousands of messages sent every week, has 8GB of RAM, 4 cores, and 80GB of disk. The CPUs are essentially always idle, but the 8GB of RAM is important.

  • We recommend using a remote postgres database for isolation, though it is not required. In the following, we discuss a relatively simple configuration with two types of servers: application servers (running Django, Tornado, RabbitMQ, Redis, Memcached, etc.) and database servers.

  • You can scale to a pretty large installation (O(~1000) concurrently active users using it to chat all day) with just a single reasonably large application server (e.g. AWS c3.2xlarge with 8 cores and 16GB of RAM) sitting mostly idle (<10% CPU used and only 4GB of the 16GB RAM actively in use). You can probably get away with half that (e.g. c3.xlarge), but ~8GB of RAM is highly recommended at scale. Beyond a 1000 active users, you will eventually want to increase the memory cap in memcached.conf from the default 512MB to avoid high rates of memcached misses.

  • For the database server, we highly recommend SSD disks, and RAM is the primary resource limitation. We have not aggressively tested for the minimum resources required, but 8 cores with 30GB of RAM (e.g. AWS’s m3.2xlarge) should suffice; you may be able to get away with less especially on the CPU side. The database load per user is pretty optimized as long as memcached is working correctly. This has not been tested, but from extrapolating the load profile, it should be possible to scale a Zulip installation to 10,000s of active users using a single large database server without doing anything complicated like sharding the database.

  • For reasonably high availability, it’s easy to run a hot spare application server and a hot spare database (using Postgres streaming replication; see the section on configuring this). Be sure to check out the section on backups if you’re hoping to run a spare application server; in particular you probably want to use the S3 backend for storing user-uploaded files and avatars and will want to make sure secrets are available on the hot spare.

  • Zulip 2.0 and later supports running multiple Tornado servers sharded by realm/organization, which is how we scale Zulip Cloud.

  • However, Zulip does not yet support dividing traffic for a single Zulip realm between multiple application servers. There are two issues: you need to share the memcached/Redis/RabbitMQ instance (these should can be moved to a network service shared by multiple servers with a bit of configuration) and the Tornado event system for pushing to browsers currently has no mechanism for multiple frontend servers (or event processes) talking to each other. One can probably get a factor of 10 in a single server’s scalability by supporting multiple tornado processes on a single server, which is also likely the first part of any project to support exchanging events amongst multiple servers. The work for changing this is pretty far along, though, and thus while not generally available yet, we can set it up for users with an enterprise support contract.

Questions, concerns, and bug reports about this area of Zulip are very welcome! This is an area we are hoping to improve.

Sections that have moved

These were once subsections of this page, but have since moved to dedicated pages; we preserve them here to avoid breaking old links.

Securing your Zulip server

Moved to Security Model.

Upgrading

Moved to Upgrading to a release.

Upgrading from a Git repository

Moved to Upgrading from a Git repository.

Upgrading the operating system

Moved to Upgrading the operating system.

API and your Zulip URL

To use the Zulip API with your Zulip server, you will need to use the API endpoint of e.g. https://zulip.example.com/api. Our Python API example scripts support this via the --site=https://zulip.example.com argument. The API bindings support it via putting site=https://zulip.example.com in your .zuliprc.

Every Zulip integration supports this sort of argument (or e.g. a ZULIP_SITE variable in a zuliprc file or the environment), but this is not yet documented for some of the integrations (the included integration documentation on /integrations will properly document how to do this for most integrations). We welcome pull requests for integrations that don’t discuss this!

Similarly, you will need to instruct your users to specify the URL for your Zulip server when using the Zulip desktop and mobile apps.

Memory leak mitigation

As a measure to mitigate the impact of potential memory leaks in one of the Zulip daemons, the service automatically restarts itself every Sunday early morning. See /etc/cron.d/restart-zulip for the precise configuration.

Management commands

Zulip has a large library of Django management commands. To use them, you will want to be logged in as the zulip user and for the purposes of this documentation, we assume the current working directory is /home/zulip/deployments/current.

Below, we show several useful examples, but there are more than 100 in total. We recommend skimming the usage docs (or if there are none, the code) of a management command before using it, since they are generally less polished and more designed for expert use than the rest of the Zulip system.

Running management commands

Many management commands require the Zulip realm/organization to interact with as an argument, which you can specify via numeric or string ID.

You can see all the organizations on your Zulip server using ./manage.py list_realms.

zulip@zulip:~$ /home/zulip/deployments/current/manage.py list_realms
id    string_id                                name
--    ---------                                ----
1     zulipinternal                            None
2                                              Zulip Community

(Note that every Zulip server has a special zulipinternal realm containing system-internal bots like welcome-bot; you are unlikely to need to interact with that realm.)

Unless you are hosting multiple organizations on your Zulip server, your single Zulip organization on the root domain will have the empty string ('') as its string_id. So you can run e.g.:

zulip@zulip:~$ /home/zulip/deployments/current/manage.py show_admins -r ''

Otherwise, the string_id will correspond to the organization’s subdomain. E.g. on it.zulip.example.com, use /home/zulip/deployments/current/manage.py show_admins -r it.

manage.py shell

You can get an iPython shell with full access to code within the Zulip project using manage.py shell, e.g., you can do the following to change a user’s email address:

$ /home/zulip/deployments/current/manage.py shell
In [1]: user_profile = get_user_profile_by_email("email@example.com")
In [2]: do_change_user_delivery_email(user_profile, "new_email@example.com")

manage.py dbshell

This will start a postgres shell connected to the Zulip database.

Grant administrator access

You can make any user a realm administrator on the command line with the knight management command:

./manage.py knight username@example.com -f

Creating API super users with manage.py

If you need to manage the IRC, Jabber, or Zephyr mirrors, you will need to create API super users. To do this, use ./manage.py knight with the --permission=api_super_user argument. See the respective integration scripts for these mirrors (under zulip/integrations/ in the Zulip Python API repo) for further detail on these.

Exporting users and realms with manage.py export

If you need to do an export of a single user or of an entire realm, we have tools in management/ that essentially export Zulip data to the file system.

export_single_user.py exports the message history and realm-public metadata for a single Zulip user (including that user’s received messages as well as their sent messages).

A good overview of the process for exporting a single realm when moving a realm to a new server (without moving a full database dump) is in management/export.py. We recommend you read the comment there for words of wisdom on speed, what is and is not exported, what will break upon a move to a new server, and suggested procedure.

Other useful manage.py commands

There are a large number of useful management commands under zerver/management/commands/; you can also see them listed using ./manage.py with no arguments.

Hosting multiple Zulip organizations

This is explained in detail on its own page.