zulip/docs/production/export-and-import.md

# Backups, export and import

Zulip has high quality export and import tools that can be used to
move data from one Zulip server to another, do backups, compliance
work, or migrate from your own servers to the hosted Zulip Cloud
service (or back):

* The [Backup](#backups) tool is designed for exact restoration of a
  Zulip server's state, for disaster recovery, testing with production
  data, or hardware migration.  This tool has a few limitations:

  * Backups must be restored on a server running the same Zulip
    version (most precisely, one where `manage.py showmigrations` has
    the same output).
  * Backups must be restored on a server running the same `postgres`
    version.
  * Migrating organizations between self-hosting and Zulip Cloud
    (generally requires renumbering all the
    users/messages/etc.).

  We highly recommend this tool in situations where it is applicable,
  because it is highly optimized and highly stable, since the hard wor
  k is done by the built-in backup feature of `postgres`.  We also
  document [backup details](#backup-details) for users managing
  backups manually.

* The logical [Data export](#data-export) tool is designed for
  migrating data between Zulip Cloud and other Zulip servers, as well
  as various auditing purposes.  The logical export tool produces a
  `.tar.gz` archive with most of the Zulip database data encoded in
  JSON files–a format shared by our [data
  import]((#import-into-a-new-zulip-server) ) tools for third-party
  services like
  [Slack](https://zulipchat.com/help/import-from-slack).

  Like the backup tool, logical data exports must be imported on a
  Zulip server running the same version.  However, these exports
  imported on Zulip servers running a different `postgres` version or
  hosting a different set of Zulip organizations.  We recommend this
  tool in cases where the backup tool isn't applicable, including
  situations where an easily machine-parsable export format is desired.

* Zulip also has an [HTML archive
  tool](https://github.com/zulip/zulip_archive), which is primarily
  intended for public archives, but can also be useful to
  inexpensively preserve public stream conversations when
  decommissioning a Zulip organization.

* It's possible to setup [postgres streaming
  replication](#postgres-streaming-replication) and the [S3 file
  upload
  backend](../production/upload-backends.html#s3-backend-configuration)
  as part of a high evailability environment.

## Backups

The Zulip server has a built-in backup tool:

```
# As the zulip user
/home/zulip/deployments/current/manage.py backup
# Or as root
su zulip -c '/home/zulip/deployments/current/manage.py backup'
```

The backup tool provides the following options:
- `--output`: Path where the output file should be stored. If no path is
 provided, the output file would be saved to a temporary directory.
- `--skip-db`: Skip backup of the database.  Useful if you're using a
  remote postgres host with its own backup system and just need to
  backup non-database state.
- `--skip-uploads`: If `LOCAL_UPLOADS_DIR` is set, user-uploaded files
  in that directory will be ignored.

This will generate a `.tar.gz` archive containing all the data stored
on your Zulip server that would be needed to restore your Zulip
server's state on another machine perfectly.

### Restoring backups

First, [install a new Zulip server through Step 3][install-server]
with the same version of both the base OS and Zulip from your previous
installation.  Then, run as root:

```
/home/zulip/deployments/current/scripts/setup/restore-backup /path/to/backup
```

When that finishes, your Zulip server should be fully operational again.

#### Changing the hostname

It's common, when testing backup restoration, to restore backups with a
different user-facing hostname than the original server to avoid
disrupting service (e.g. `zuliptest.example.com` rather than
`zulip.example.com`).

If you do so, just like any other time you change the hostname, you'll
need to [update `EXTERNAL_HOST`](../production/settings.md) and then
restart the Zulip server (after backup restoration completes).

Until you do, your Zulip server will think its user-facing hostname is
still `zulip.example.com` and will return HTTP `400 BAD REQUEST`
errors when trying to access it via `zuliptest.example.com`.

#### Inspecting a backup tarball

If you're not sure what versions were in use when a given backup was
created, you can get that information via the files in the backup
tarball: `postgres-version`, `os-version`, and `zulip-version`.  The
following command may be useful for viewing these files without
extracting the entire archive.

```
tar -Oaxf /path/to/archive/zulip-backup-rest.tar.gz zulip-backup/zulip-version
```

[install-server]: ../production/install.md

### What is included

Backups contain everything you need to fully restore your Zulip
server, including the database, settings, secrets from
`/etc/zulip`, and user-uploaded files stored on the Zulip server.

The following data is not included in these backup archives,
and you may want to backup separately:

* The server access/error logs from `/var/log/zulip`.  The Zulip
  server only appends to logs, and they can be very large compared to
  the rest of the data for a Zulip server.

* Files uploaded with the Zulip
  [S3 file upload backend](../production/upload-backends.md).  We
  don't include these for two reasons. First, the uploaded file data
  in S3 can easily be many times larger than the rest of the backup,
  and downloading it all to a server doing a backup could easily
  exceed its disk capacity.  Additionally, S3 is a reliable persistent
  storage system with its own high-quality tools for doing backups.

* Transient data present in Zulip's RabbitMQ queues.  For example, a
  record that a missed-message email for a given Zulip message is
  scheduled to be sent to a given user in 2 minutes, if the recipient
  user doesn't interact with Zulip during that time window.  You can
  check their status using `rabbitmq list_queues` as root.

* Certain highly transient state that Zulip doesn't store in a
  database, such as typing status, API rate-limiting counters,
  etc. that would have no value 1 minute after the backup is
  completed.

* SSL certificates.  Since these are particularly security-sensitive
  and either trivially replaced (if generated via Certbot) or provided
  by the system administrator.

#### Backup details

This section is primarily for users managing backups themselves
(E.g. if they're using a remote postgres database with an existing
backup strategy), and also serves as documentation for what is
included in the backups generated by Zulip's standard tools.  The
data includes:

* The postgres database.  You can back it up like any postgres
database. We have some example tooling for doing that incrementally
into S3 using [wal-e](https://github.com/wal-e/wal-e) in
`puppet/zulip_ops/manifests/postgres_common.pp`.
In short, this requires:
  - Zulip 1.4 or newer release.
  - An Amazon S3 bucket for storing the backups.
  - `/etc/zulip/zulip-secrets.conf` on the postgres server like this:
    ```
    [secrets]
    s3_backups_key = # aws public key
    s3_backups_secret_key =  # aws secret key
    s3_backups_bucket = # name of S3 backup
    ```
  - A cron job to run `/usr/local/bin/pg_backup_and_purge.py`. There's puppet
  config for this in `puppet/zulip_internal/manifests/postgres_common.pp`.
  - Verification that backups are running via
  `/usr/lib/nagios/plugins/zulip_postgres_common/check_postgres_backup`.

* Any user-uploaded files.  If you're using S3 as storage for file
uploads, this is backed up in S3. But if you have instead set
`LOCAL_UPLOADS_DIR`, any files uploaded by users (including avatars)
will be stored in that directory and you'll want to back it up.

* Your Zulip configuration including secrets from `/etc/zulip/`.
E.g. if you lose the value of `secret_key`, all users will need to
login again when you setup a replacement server since you won't be
able to verify their cookies. If you lose `avatar_salt`, any
user-uploaded avatars will need to be re-uploaded (since avatar
filenames are computed using a hash of `avatar_salt` and user's
email), etc.

[export-import]: ../production/export-and-import.md

### Restore from manual backups

To restore from a manual backup, the process is basically the reverse of the above:

* Install new server as normal by downloading a Zulip release tarball
  and then using `scripts/setup/install`. You don't need
  to run the `initialize-database` second stage which puts default
  data into the database.

* Unpack to `/etc/zulip` the `settings.py` and `zulip-secrets.conf` files
  from your backups.

* Restore your database from the backup using `wal-e`. If you ran
  `initialize-database` anyway above, you'll want to run
  `scripts/setup/postgres-init-db` to drop the initial database first.

* Reconfigure rabbitmq to use the password from `secrets.conf`
  by running, as root, `scripts/setup/configure-rabbitmq`.

* If you're using local file uploads, restore those files to the path
  specified by `settings.LOCAL_UPLOADS_DIR` and (if appropriate) any
  logs.

* Start the server using `scripts/restart-server`.

This restoration process can also be used to migrate a Zulip
installation from one server to another.

We recommend running a disaster recovery after setting up your backups to
confirm that your backups are working. You may also want to monitor
that they are up to date using the Nagios plugin at:
`puppet/zulip_ops/files/nagios_plugins/check_postgres_backup`.

## Postgres streaming replication

Zulip has database configuration for using Postgres streaming
replication. You can see the configuration in these files:

* `puppet/zulip_ops/manifests/postgres_slave.pp`
* `puppet/zulip_ops/manifests/postgres_master.pp`
* `puppet/zulip_ops/files/postgresql/*`

We use this configuration for zulipchat.com, and it works well in
production, but it's not fully generic.  Contributions to make it a
supported and documented option for other installations are
appreciated.

## Data export

Zulip's powerful data export tool is designed to handle migration of a
Zulip organization between different hardware platforms; as a result,
these exports contain all non-transient data for a Zulip organization,
with the exception of passwords and API keys.

We recommend using the [backup tool](#backups) if your primary goal is
backups.

### Preventing changes during the export

For best results, you'll want to shut down access to the organization
before exporting; so that nobody can send new messages (etc.)  while
you're exporting data.  There are two ways to do this:

1. `supervisorctl stop all`, which stops the whole server.  This is
preferred if you're not hosting multiple organizations, because it has
no side effects other than disabling the Zulip server for the
duration.
1. `manage.py deactivate_realm  -r 'target_org'`, which deactivates the target
organization, logging out all active login sessions and preventing all
accounts from logging in or accessing the API.  This is
preferred for environments like Zulip Cloud where you might want to
export a single organization without disrupting any other users, and
the intent is to move hosting of the organization (and forcing users
to re-login would be required as part of the hosting migration
anyway).

We include both options in the instructions below, commented out so
that neither runs (using the `# ` at the start of the lines).  If
you'd like to use one of these options, remove the `# ` at the start
of the lines for the appropriate option.

### Export your Zulip data

Log in to a shell on your Zulip server as the `zulip` user. Run the
following commands:

```
cd /home/zulip/deployments/current
# supervisorctl stop all # Stops the Zulip server
# ./manage.py deactivate_realm -r ''  # Deactivates the organization
./manage.py export -r ''  # Exports the data
```

(The `-r` option lets you specify the organization to export; `''` is
the default organization hosted at the Zulip server's root domain.)

This will generate a tarred archive with a name like
`/tmp/zulip-export-zcmpxfm6.tar.gz`.  The archive contains several
JSON files (containing the Zulip organization's data) as well as an
archive of all the organization's uploaded files.

## Import into a new Zulip server

1. [Install a new Zulip server](../production/install.md),
**skipping Step 3** (you'll create your Zulip organization via the data
 import tool instead).  
    * Ensure that the Zulip server you're importing into is running the same
version of Zulip as the server you're exporting from.

    * For exports from zulipchat.com, run the following:

      ```
      /home/zulip/deployments/current/scripts/upgrade-zulip-from-git master
      ```

    * Note that if your server has 2GB of RAM or less, you'll want to read the
    detailed instructions [here][upgrade-zulip-from-git].
    It is not sufficient to be on the latest stable release, as zulipchat.com is
    often several months of development ahead of the latest release.

2. If your new Zulip server is meant to fully replace a previous Zulip
server, you may want to copy the contents of `/etc/zulip` to your new
server to reuse the server-level configuration and
secret keys from your old server.  See our
[documentation on backups](#backups) for details on the contents of
this directory.

3. Log in to a shell on your Zulip server as the `zulip` user. Run the
following commands, replacing the filename with the path to your data
export tarball:

```
cd ~
tar -xf /path/to/export/file/zulip-export-zcmpxfm6.tar.gz
cd /home/zulip/deployments/current
./manage.py import '' ~/zulip-export-zcmpxfm6
# supervisorctl start all # Starts the Zulip server
# ./manage.py reactivate_realm -r ''  # Reactivates the organization
```

This could take several minutes to run depending on how much data you're
importing.

[upgrade-zulip-from-git]: ../production/maintain-secure-upgrade.html#upgrading-from-a-git-repository

#### Import options

The commands above create an imported organization on the root domain
(`EXTERNAL_HOST`) of the Zulip installation. You can also import into a
custom subdomain, e.g. if you already have an existing organization on the
root domain. Replace the last two lines above with the following, after replacing
`<subdomain>` with the desired subdomain.

```
./manage.py import <subdomain> ~/zulip-export-zcmpxfm6
./manage.py reactivate_realm -r <subdomain>  # Reactivates the organization
```

### Logging in

Once the import completes, all your users will have accounts in your
new Zulip organization, but those accounts won't have passwords yet
(since for security reasons, passwords are not exported).
Your users will need to either authenticate using something like
Google auth or start by resetting their passwords.

You can use the `./manage.py send_password_reset_email` command to
send password reset emails to your users.  We
recommend starting with sending one to yourself for testing:

```
./manage.py send_password_reset_email -u username@example.com
```

and then once you're ready, you can email them to everyone using e.g.
```
./manage.py send_password_reset_email -r '' --all-users
```

(replace `''` with your subdomain if you're using one).

### Deleting and re-importing

If you did a test import of a Zulip organization, you may want to
delete the test import data from your Zulip server before doing a
final import.  You can **permanently delete** all data from a Zulip
organization using the following procedure:

* Start a [Zulip management shell](../production/maintain-secure-upgrade.html#manage-py-shell)
* In the management shell, run the following commands, replacing `""`
  with the subdomain if [you are hosting the organization on a
  subdomain](../production/multiple-organizations.md):

```
realm = Realm.objects.get(string_id="")
realm.delete()
```

The output contains details on the objects deleted from the database.

Now, exit the management shell and run this to clear Zulip's cache:
```
/home/zulip/deployments/current/scripts/setup/flush-memcached
```

Assuming you're using the
[local file uploads backend](../production/upload-backends.md), you
can additionally delete all file uploads, avatars, and custom emoji on
a Zulip server (across **all organizations**) with the following
command:

```
rm -rf /home/zulip/uploads/*/*
```

If you're hosting multiple organizations and would like to remove
uploads from a single organization, you'll need to access `realm.id`
in the management shell before deleting the organization from the
database (this will be `2` for the first organization created on a
Zulip server, shown in the example below), e.g.:

```
rm -rf /home/zulip/uploads/*/2/
```

Once that's done, you can simply re-run the import process.