A system like ownCloud sometimes requires tasks to be done on a regular basis without requiring user interaction or hindering ownCloud’s performance. For that reason, as a system administrator, you can configure background jobs (for example, database clean-ups) to be executed without any user interaction.
These jobs are typically referred to as
Cron Jobs. Cron jobs are commands or
shell-based scripts that are scheduled to periodically run at fixed
times, dates, or intervals.
cron.php is an ownCloud internal process
that runs such background jobs on demand.
ownCloud plug-in applications can register actions with
automatically to take care of typical housekeeping operations. These
actions can include garbage collecting of temporary files or checking
for newly updated files using
filescan() on externally mounted file
You can decide how often jobs get processed, we recommend an interval of one minute.
You can schedule Cron jobs in three ways: Cron, Webcron, or AJAX. These can all be configured in the admin settings menu. However, the recommended method is to use Cron. The following sections describe the differences between each method.
There are a number of things to keep in mind when choosing an automation option:
Firstly, while the default method is AJAX, though the preferred way is to use Cron. The reason for this distinction is that AJAX is easier to get up and running. As a result, it makes sense (often times) to accept it in the interests of expediency.
However, doing so is known to cause issues, such as backlogs and potentially not running every job on a heavily-loaded system. What’s more, an increasing amount of ownCloud automation has been migrated from AJAX to Cron in recent versions. For this reason, we encourage you to not use it for too long — especially if your site is rapidly growing.
Secondly, while Webcron is better than AJAX, it too has limitations. For example, running Webcron will only remove a single item from the job queue, not all of them. Cron, however, will clear the entire queue.
|It’s for this reason that we encourage you to use Cron — if at all possible.|
Using the operating system Cron feature is the preferred method for executing regular tasks. This method enables the execution of scheduled jobs without the inherent limitations which the web server might have.
For example, to run a Cron job on a nix system every minute, under the
default web server user (often,
wwwrun) you must set up
the following Cron job to call the *cron.php script:
# crontab -u www-data -e * * * * * /usr/bin/php -f /path/to/your/owncloud/cron.php
You can verify if the cron job has been added and scheduled by executing:
# crontab -u www-data -l * * * * * /usr/bin/php -f /path/to/your/owncloud/cron.php
|You have to make sure that PHP is found by Cron; hence why we’ve deliberately added the full path.|
Please refer to the crontab man page for the exact command syntax if you don’t want to have it run every minute.
|There are other methods to invoke programs by the system regularly, e.g., systemd timers|
By registering your ownCloud
cron.php script address as an external
webcron service (for example, easyCron), you
ensure that background jobs are executed regularly. To use this type of
service, your external webcron service must be able to access your
ownCloud server using the Internet. For example:
URL to call: http[s]://<domain-of-your-server>/owncloud/cron.php
The AJAX scheduling method is the default option. However, it is also the least reliable. Each time a user visits the ownCloud page, a single background job is executed. The advantage of this mechanism, however, is that it does not require access to the system nor registration with a third party service. The disadvantage of this mechanism, when compared to the Webcron service, is that it requires regular visits to the page for it to be triggered.
|Especially when using the Activity App or external storages, where new files are added, updated, or deleted one of the other methods should be used.|
Regardless of the approach which you take, since ownCloud 9.1, Cron jobs
can be run in parallel. This is done by running
times. Depending on the process which you’re automating, this may not be
necessary. However, for longer-running tasks, such as those which are
LDAP related, it may be very beneficial.
There is no way to do so via the ownCloud UI. But, the most direct way
to do so, is by opening three console tabs and in each one run
php cron.php. Each of these processes would acquire their own list of
jobs to process without overlapping any other.
A number of existing background jobs are available to be run just for specific tasks.
These jobs are generally only needed on large instances and can be run as background jobs.
If the number of users in your installation ranges between 1,000 and 3,000, or if you’re using LDAP and it becomes a bottleneck, then admins can delete several entries in the
If used, these should be scheduled to run on a daily basis.
While not exhaustive, these include:
The CleanupChunks command,
occ dav:cleanup-chunks, will clean up outdated chunks (uploaded files) more than a certain number of days old and needs to be added to your crontab.
There is no matching background job to delete from the
The ExpireTrash job, contained in
OCA\Files_Trashbin\BackgroundJob\ExpireTrash, will remove any file in
the ownCloud trash bin which is older than the specified maximum file
retention time. It can be run, as follows, using the OCC command:
The ExpireVersions job, contained in
OCA\Files_Versions\BackgroundJob\ExpireVersions, will expire versions
of files which are older than the specified maximum version retention
time. It can be run, as follows, using the OCC command:
Please take care when adding
The CardDAV SyncJob, contained in
OCA\DAV\CardDAV\SyncJob, syncs the
local system address book, updating any existing contacts, and deleting
any expired contacts. It can be run, as follows, using the OCC command: