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.Dd December 18, 2016
.Dt PROMETHEUS_SYSCTL_EXPORTER 8
.Os
.Sh NAME
.Nm prometheus_sysctl_exporter
.Nd print kernel state as Prometheus metrics
.Sh SYNOPSIS
.Nm prometheus_sysctl_exporter
.Op Fl dgh
.Op Ar prefix ...
.Sh DESCRIPTION
Prometheus is a monitoring system that gathers metrics from its targets
by fetching them through HTTP GET requests.
Metrics are identified by a name and an optional set of labels.
Sample values are required to be numerical.
.Pp
The
.Nm
utility prints the values of sysctl nodes to standard output,
formatted such that they can be scraped by Prometheus directly.
By default,
it prints metrics for all numerically representable nodes in the sysctl
namespace.
It is also possible to limit output to a smaller number of metrics by
specifying one or more prefixes as arguments.
.Pp
Metrics printed by this utility are named
.Ql sysctl_ ,
followed by the name of the sysctl node having its
.Ql .\&
separators replaced by
.Ql _ .
Components on which it is desirable to aggregate (e.g.,
names of devices) are omitted from the metric's name,
but are appended as labels instead.
.Pp
There are two different methods for exporting the output of
.Nm
to Prometheus.
The first method is to periodically invoke this utility through
.Xr cron 8
and store its output in a textfile.
The metrics in this textfile can then be served over HTTP using the
Prometheus node exporter's textfile collector.
The second method is to run this utility through
.Xr inetd 8 .
TCP port 9124 has been allocated for this purpose.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl d
Print descriptions of metrics when available.
.It Fl g
Gzip compresses the HTTP response body.
.It Fl h
Precede the output with a HTTP response header.
This flag is required when running this utility through
.Xr inetd 8 .
.El
.Sh SEE ALSO
.Xr cron 8 ,
.Xr inetd 8 ,
.Xr sysctl 8 ,
.Xr SYSCTL_ADD_NODE_WITH_LABEL 9
.Pp
Prometheus project:
.Pa https://prometheus.io/ .
.Pp
Prometheus exposition formats:
.Pa https://prometheus.io/docs/instrumenting/exposition_formats/ .
.Pp
Prometheus node exporter:
.Pa https://github.com/prometheus/node_exporter .
.Pp
Prometheus default port allocations:
.Pa https://github.com/prometheus/prometheus/wiki/Default-port-allocations .
.Sh HISTORY
.Nm
first appeared in
.Fx 12.0 .
.Sh AUTHORS
.An Nuxi : Pa https://nuxi.nl/ .
