zrepl/docs/usage.rst
2019-03-20 19:44:15 +01:00

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.. _usage:
*****
Usage
*****
============
CLI Overview
============
.. NOTE::
The zrepl binary is self-documenting:
run ``zrepl help`` for an overview of the available subcommands or ``zrepl SUBCOMMAND --help`` for information on available flags, etc.
.. _cli-signal-wakeup:
.. list-table::
:widths: 30 70
:header-rows: 1
* - Subcommand
- Description
* - ``zrepl help``
- show subcommand overview
* - ``zrepl daemon``
- run the daemon, required for all zrepl functionality
* - ``zrepl status``
- show job activity, or with ``--raw`` for JSON output
* - ``zrepl stdinserver``
- see :ref:`transport-ssh+stdinserver`
* - ``zrepl signal wakeup JOB``
- manually trigger replication + pruning of JOB
* - ``zrepl signal reset JOB``
- manually abort current replication + pruning of JOB
* - ``zrepl configcheck``
- check if config can be parsed without errors
.. _usage-zrepl-daemon:
============
zrepl daemon
============
All actual work zrepl does is performed by a daemon process.
The daemon supports structured :ref:`logging <logging>` and provides :ref:`monitoring endpoints <monitoring>`.
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.
Systemd Unit File
~~~~~~~~~~~~~~~~~
A systemd service defintion template is available in :repomasterlink:`dist/systemd`.
Note that some of the options only work on recent versions of systemd.
Any help & improvements are very welcome, see :issue:`145`.