zrepl/docs/usage.rst

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.. _usage:
*****
Usage
*****
============
CLI Overview
============
.. NOTE::
To avoid duplication, the zrepl binary is self-documenting:
invoke any subcommand at any level with the ``--help`` flag to get information on the subcommand, available flags, etc.
.. list-table::
:widths: 30 70
:header-rows: 1
* - Subcommand
- Description
* - ``zrepl daemon``
- run the daemon, required for all zrepl functionality
* - ``zrepl control``
- control / query the daemon
* - ``zrepl control status``
- show job activity / monitoring (``--format raw``)
* - ``zrepl stdinserver``
- see :ref:`transport-ssh+stdinserver`
.. _usage-zrepl-daemon:
============
zrepl daemon
============
All actual work zrepl does is performed by a daemon process.
Logging is configurable via the config file. Please refer to the :ref:`logging documention <logging>`.
When installating from a package, the package maintainer should have provided an init script / systemd.service file.
You should thus be able to start zrepl daemon using your init system.
Alternatively, or for running zrepl in the foreground, simply execute ``zrepl daemon``.
Note that you won't see much output with the :ref:`default logging configuration<logging-default-config>`:
.. ATTENTION::
Make sure to actually monitor the error level output of zrepl: some configuration errors will not make the daemon exit.
Example: if the daemon cannot create the :ref:`transport-ssh+stdinserver` sockets in the runtime directory,
it will emit an error message but not exit because other tasks such as periodic snapshots & pruning are of equal importance.
.. _usage-zrepl-daemon-restarting:
Restarting
~~~~~~~~~~
The daemon handles SIGINT and SIGTERM for graceful shutdown.
Graceful shutdown means at worst that a job will not be rescheduled for the next interval.
The daemon exits as soon as all jobs have reported shut down.