svn commit: r310354 - in head/usr.sbin: . prometheus_sysctl_exporter
Adrian Chadd
adrian.chadd at gmail.com
Wed Dec 21 17:32:08 UTC 2016
heh,
in an ideal world we'd not call this "prometheus", it'd just be the
way we export sysctl data via 'sysctl' in a machine parsable format.
Ok, since it's HTTP/gzip, maybe a separate standalone program is cool,
but it doesn't have to be specific to prometheus. :-)
That way anyone wanting to write a plugin for consuming freebsd data
can just use this program as the API contract.
Maybe just "sysctl_export" would be fine. I'd like to encourage other
consumers to use it, including existing ones that currently do all the
silly hijinx. :)
What do you think?
-adrian
On 21 December 2016 at 00:29, Ed Schouten <ed at freebsd.org> wrote:
> Author: ed
> Date: Wed Dec 21 08:29:44 2016
> New Revision: 310354
> URL: https://svnweb.freebsd.org/changeset/base/310354
>
> Log:
> Add a Prometheus exporter for sysctl values.
>
> Now that we have our sysctl tree annotated with aggregation labels,
> let's go ahead and provide a very simple utility for exporting the
> sysctl tree in Prometheus' format. It can either be used in conjunction
> with the Prometheus node exporter or run through inetd(8).
>
> The reason why I'm opting for having it in the base system is because it
> has a pretty strong integration with some of sysctl's innards, such as
> access to iterators, name lookups, metadata and type information. As I
> am investigating whether we can add histograms as native types to sysctl
> as well, this integration will only get stronger as we go along. That's
> why it would be safer to oversee the development of this exporter
> ourselves, as opposed to having it as an external project.
>
> This exporter is remarkably compact, especially when compared to the
> official Linux binary of the Prometheus node exporter (16 KB vs 12 MB).
> I guess this could be an interesting aspect for monitoring embedded
> FreeBSD-based systems.
>
> Differential Revision: https://reviews.freebsd.org/D8792
>
> Added:
> head/usr.sbin/prometheus_sysctl_exporter/
> head/usr.sbin/prometheus_sysctl_exporter/Makefile (contents, props changed)
> head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.8 (contents, props changed)
> head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.c (contents, props changed)
> Modified:
> head/usr.sbin/Makefile
>
> Modified: head/usr.sbin/Makefile
> ==============================================================================
> --- head/usr.sbin/Makefile Wed Dec 21 07:26:04 2016 (r310353)
> +++ head/usr.sbin/Makefile Wed Dec 21 08:29:44 2016 (r310354)
> @@ -62,6 +62,7 @@ SUBDIR= adduser \
> periodic \
> powerd \
> procctl \
> + prometheus_sysctl_exporter \
> pstat \
> pw \
> pwd_mkdb \
>
> Added: head/usr.sbin/prometheus_sysctl_exporter/Makefile
> ==============================================================================
> --- /dev/null 00:00:00 1970 (empty, because file is newly added)
> +++ head/usr.sbin/prometheus_sysctl_exporter/Makefile Wed Dec 21 08:29:44 2016 (r310354)
> @@ -0,0 +1,8 @@
> +# $FreeBSD$
> +
> +PROG= prometheus_sysctl_exporter
> +MAN= prometheus_sysctl_exporter.8
> +
> +LIBADD= m z
> +
> +.include <bsd.prog.mk>
>
> Added: head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.8
> ==============================================================================
> --- /dev/null 00:00:00 1970 (empty, because file is newly added)
> +++ head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.8 Wed Dec 21 08:29:44 2016 (r310354)
> @@ -0,0 +1,106 @@
> +.\" Copyright (c) 2016 Nuxi, https://nuxi.nl/
> +.\"
> +.\" Redistribution and use in source and binary forms, with or without
> +.\" modification, are permitted provided that the following conditions
> +.\" are met:
> +.\" 1. Redistributions of source code must retain the above copyright
> +.\" notice, this list of conditions and the following disclaimer.
> +.\" 2. Redistributions in binary form must reproduce the above copyright
> +.\" notice, this list of conditions and the following disclaimer in the
> +.\" documentation and/or other materials provided with the distribution.
> +.\"
> +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
> +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> +.\" SUCH DAMAGE.
> +.\"
> +.\" $FreeBSD$
> +.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/ .
>
> Added: head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.c
> ==============================================================================
> --- /dev/null 00:00:00 1970 (empty, because file is newly added)
> +++ head/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.c Wed Dec 21 08:29:44 2016 (r310354)
> @@ -0,0 +1,652 @@
> +/*-
> + * Copyright (c) 2016 Nuxi, https://nuxi.nl/
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
> + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> + * SUCH DAMAGE.
> + */
> +
> +#include <sys/cdefs.h>
> +__FBSDID("$FreeBSD$");
> +
> +#include <sys/param.h>
> +#include <sys/resource.h>
> +#include <sys/socket.h>
> +#include <sys/sysctl.h>
> +
> +#include <assert.h>
> +#include <err.h>
> +#include <errno.h>
> +#include <math.h>
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <zlib.h>
> +
> +/*
> + * Cursor for iterating over all of the system's sysctl OIDs.
> + */
> +struct oid {
> + int id[CTL_MAXNAME];
> + size_t len;
> +};
> +
> +/* Initializes the cursor to point to start of the tree. */
> +static void
> +oid_get_root(struct oid *o)
> +{
> +
> + o->id[0] = 1;
> + o->len = 1;
> +}
> +
> +/* Obtains the OID for a sysctl by name. */
> +static void
> +oid_get_by_name(struct oid *o, const char *name)
> +{
> +
> + o->len = nitems(o->id);
> + if (sysctlnametomib(name, o->id, &o->len) != 0)
> + err(1, "sysctl(%s)", name);
> +}
> +
> +/* Returns whether an OID is placed below another OID. */
> +static bool
> +oid_is_beneath(struct oid *oa, struct oid *ob)
> +{
> +
> + return (oa->len >= ob->len &&
> + memcmp(oa->id, ob->id, ob->len * sizeof(oa->id[0])) == 0);
> +}
> +
> +/* Advances the cursor to the next OID. */
> +static bool
> +oid_get_next(const struct oid *cur, struct oid *next)
> +{
> + int lookup[CTL_MAXNAME + 2];
> + size_t nextsize;
> +
> + lookup[0] = 0;
> + lookup[1] = 2;
> + memcpy(lookup + 2, cur->id, cur->len * sizeof(lookup[0]));
> + nextsize = sizeof(next->id);
> + if (sysctl(lookup, 2 + cur->len, &next->id, &nextsize, 0, 0) != 0) {
> + if (errno == ENOENT)
> + return (false);
> + err(1, "sysctl(next)");
> + }
> + next->len = nextsize / sizeof(next->id[0]);
> + return (true);
> +}
> +
> +/*
> + * OID formatting metadata.
> + */
> +struct oidformat {
> + unsigned int kind;
> + char format[BUFSIZ];
> +};
> +
> +/* Returns whether the OID represents a temperature value. */
> +static bool
> +oidformat_is_temperature(const struct oidformat *of)
> +{
> +
> + return (of->format[0] == 'I' && of->format[1] == 'K');
> +}
> +
> +/* Returns whether the OID represents a timeval structure. */
> +static bool
> +oidformat_is_timeval(const struct oidformat *of)
> +{
> +
> + return (strcmp(of->format, "S,timeval") == 0);
> +}
> +
> +/* Fetches the formatting metadata for an OID. */
> +static bool
> +oid_get_format(const struct oid *o, struct oidformat *of)
> +{
> + int lookup[CTL_MAXNAME + 2];
> + size_t oflen;
> +
> + lookup[0] = 0;
> + lookup[1] = 4;
> + memcpy(lookup + 2, o->id, o->len * sizeof(lookup[0]));
> + oflen = sizeof(*of);
> + if (sysctl(lookup, 2 + o->len, of, &oflen, 0, 0) != 0) {
> + if (errno == ENOENT)
> + return (false);
> + err(1, "sysctl(oidfmt)");
> + }
> + return (true);
> +}
> +
> +/*
> + * Container for holding the value of an OID.
> + */
> +struct oidvalue {
> + enum { SIGNED, UNSIGNED, FLOAT } type;
> + union {
> + intmax_t s;
> + uintmax_t u;
> + double f;
> + } value;
> +};
> +
> +/* Extracts the value of an OID, converting it to a floating-point number. */
> +static double
> +oidvalue_get_float(const struct oidvalue *ov)
> +{
> +
> + switch (ov->type) {
> + case SIGNED:
> + return (ov->value.s);
> + case UNSIGNED:
> + return (ov->value.u);
> + case FLOAT:
> + return (ov->value.f);
> + default:
> + assert(0 && "Unknown value type");
> + }
> +}
> +
> +/* Sets the value of an OID as a signed integer. */
> +static void
> +oidvalue_set_signed(struct oidvalue *ov, intmax_t s)
> +{
> +
> + ov->type = SIGNED;
> + ov->value.s = s;
> +}
> +
> +/* Sets the value of an OID as an unsigned integer. */
> +static void
> +oidvalue_set_unsigned(struct oidvalue *ov, uintmax_t u)
> +{
> +
> + ov->type = UNSIGNED;
> + ov->value.u = u;
> +}
> +
> +/* Sets the value of an OID as a floating-point number. */
> +static void
> +oidvalue_set_float(struct oidvalue *ov, double f)
> +{
> +
> + ov->type = FLOAT;
> + ov->value.f = f;
> +}
> +
> +/* Prints the value of an OID to a file stream. */
> +static void
> +oidvalue_print(const struct oidvalue *ov, FILE *fp)
> +{
> +
> + switch (ov->type) {
> + case SIGNED:
> + fprintf(fp, "%jd", ov->value.s);
> + break;
> + case UNSIGNED:
> + fprintf(fp, "%ju", ov->value.u);
> + break;
> + case FLOAT:
> + switch (fpclassify(ov->value.f)) {
> + case FP_INFINITE:
> + if (signbit(ov->value.f))
> + fprintf(fp, "-Inf");
> + else
> + fprintf(fp, "+Inf");
> + break;
> + case FP_NAN:
> + fprintf(fp, "Nan");
> + break;
> + default:
> + fprintf(fp, "%.6f", ov->value.f);
> + break;
> + }
> + break;
> + }
> +}
> +
> +/* Fetches the value of an OID. */
> +static bool
> +oid_get_value(const struct oid *o, const struct oidformat *of,
> + struct oidvalue *ov)
> +{
> +
> + switch (of->kind & CTLTYPE) {
> +#define GET_VALUE(ctltype, type) \
> + case (ctltype): { \
> + type value; \
> + size_t valuesize; \
> + \
> + valuesize = sizeof(value); \
> + if (sysctl(o->id, o->len, &value, &valuesize, 0, 0) != 0) \
> + return (false); \
> + if ((type)-1 > 0) \
> + oidvalue_set_unsigned(ov, value); \
> + else \
> + oidvalue_set_signed(ov, value); \
> + break; \
> + }
> + GET_VALUE(CTLTYPE_INT, int);
> + GET_VALUE(CTLTYPE_UINT, unsigned int);
> + GET_VALUE(CTLTYPE_LONG, long);
> + GET_VALUE(CTLTYPE_ULONG, unsigned long);
> + GET_VALUE(CTLTYPE_S8, int8_t);
> + GET_VALUE(CTLTYPE_U8, uint8_t);
> + GET_VALUE(CTLTYPE_S16, int16_t);
> + GET_VALUE(CTLTYPE_U16, uint16_t);
> + GET_VALUE(CTLTYPE_S32, int32_t);
> + GET_VALUE(CTLTYPE_U32, uint32_t);
> + GET_VALUE(CTLTYPE_S64, int64_t);
> + GET_VALUE(CTLTYPE_U64, uint64_t);
> +#undef GET_VALUE
> + case CTLTYPE_OPAQUE:
> + if (oidformat_is_timeval(of)) {
> + struct timeval tv;
> + size_t tvsize;
> +
> + tvsize = sizeof(tv);
> + if (sysctl(o->id, o->len, &tv, &tvsize, 0, 0) != 0)
> + return (false);
> + oidvalue_set_float(ov,
> + (double)tv.tv_sec + (double)tv.tv_usec / 1000000);
> + return (true);
> + } else if (strcmp(of->format, "S,loadavg") == 0) {
> + struct loadavg la;
> + size_t lasize;
> +
> + /*
> + * Only return the one minute load average, as
> + * the others can be inferred using avg_over_time().
> + */
> + lasize = sizeof(la);
> + if (sysctl(o->id, o->len, &la, &lasize, 0, 0) != 0)
> + return (false);
> + oidvalue_set_float(ov,
> + (double)la.ldavg[0] / (double)la.fscale);
> + return (true);
> + }
> + return (false);
> + default:
> + return (false);
> + }
> +
> + /* Convert temperatures from decikelvin to degrees Celcius. */
> + if (oidformat_is_temperature(of)) {
> + double v;
> + int e;
> +
> + v = oidvalue_get_float(ov);
> + if (v < 0) {
> + oidvalue_set_float(ov, NAN);
> + } else {
> + e = of->format[2] >= '0' && of->format[2] <= '9' ?
> + of->format[2] - '0' : 1;
> + oidvalue_set_float(ov, v / pow(10, e) - 273.15);
> + }
> + }
> + return (true);
> +}
> +
> +/*
> + * The full name of an OID, stored as a series of components.
> + */
> +struct oidname {
> + struct oid oid;
> + char names[BUFSIZ];
> + char labels[BUFSIZ];
> +};
> +
> +/*
> + * Initializes the OID name object with an empty value.
> + */
> +static void
> +oidname_init(struct oidname *on)
> +{
> +
> + on->oid.len = 0;
> +}
> +
> +/* Fetches the name and labels of an OID, reusing the previous results. */
> +static void
> +oid_get_name(const struct oid *o, struct oidname *on)
> +{
> + int lookup[CTL_MAXNAME + 2];
> + char *c, *label;
> + size_t i, len;
> +
> + /* Fetch the name and split it up in separate components. */
> + lookup[0] = 0;
> + lookup[1] = 1;
> + memcpy(lookup + 2, o->id, o->len * sizeof(lookup[0]));
> + len = sizeof(on->names);
> + if (sysctl(lookup, 2 + o->len, on->names, &len, 0, 0) != 0)
> + err(1, "sysctl(name)");
> + for (c = strchr(on->names, '.'); c != NULL; c = strchr(c + 1, '.'))
> + *c = '\0';
> +
> + /* No need to fetch labels for components that we already have. */
> + label = on->labels;
> + for (i = 0; i < o->len && i < on->oid.len && o->id[i] == on->oid.id[i];
> + ++i)
> + label += strlen(label) + 1;
> +
> + /* Fetch the remaining labels. */
> + lookup[1] = 6;
> + for (; i < o->len; ++i) {
> + len = on->labels + sizeof(on->labels) - label;
> + if (sysctl(lookup, 2 + i + 1, label, &len, 0, 0) == 0) {
> + label += len;
> + } else if (errno == ENOENT) {
> + *label++ = '\0';
> + } else {
> + err(1, "sysctl(oidlabel)");
> + }
> + }
> + on->oid = *o;
> +}
> +
> +/* Prints the name and labels of an OID to a file stream. */
> +static void
> +oidname_print(const struct oidname *on, const struct oidformat *of,
> + FILE *fp)
> +{
> + const char *name, *label;
> + size_t i;
> + char separator;
> +
> + /* Print the name of the metric. */
> + fprintf(fp, "sysctl");
> + name = on->names;
> + label = on->labels;
> + for (i = 0; i < on->oid.len; ++i) {
> + if (*label == '\0') {
> + assert(name[strspn(name,
> + "abcdefghijklmnopqrstuvwxyz"
> + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
> + "0123456789_")] == '\0');
> + fprintf(fp, "_%s", name);
> + }
> + name += strlen(name) + 1;
> + label += strlen(label) + 1;
> + }
> + if (oidformat_is_temperature(of))
> + fprintf(fp, "_celcius");
> + else if (oidformat_is_timeval(of))
> + fprintf(fp, "_seconds");
> +
> + /* Print the labels of the metric. */
> + name = on->names;
> + label = on->labels;
> + separator = '{';
> + for (i = 0; i < on->oid.len; ++i) {
> + if (*label != '\0') {
> + assert(name[strspn(name,
> + "abcdefghijklmnopqrstuvwxyz"
> + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
> + "0123456789_-")] == '\0');
> + assert(label[strspn(label,
> + "abcdefghijklmnopqrstuvwxyz"
> + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
> + "0123456789_")] == '\0');
> + fprintf(fp, "%c%s=\"%s\"", separator, label, name);
> + separator = ',';
> + }
> + name += strlen(name) + 1;
> + label += strlen(label) + 1;
> + }
> + if (separator != '{')
> + fputc('}', fp);
> +}
> +
> +/* Returns whether the OID name has any labels associated to it. */
> +static bool
> +oidname_has_labels(const struct oidname *on)
> +{
> + size_t i;
> +
> + for (i = 0; i < on->oid.len; ++i)
> + if (on->labels[i] != 0)
> + return (true);
> + return (false);
> +}
> +
> +/*
> + * The description of an OID.
> + */
> +struct oiddescription {
> + char description[BUFSIZ];
> +};
> +
> +/*
> + * Fetches the description of an OID.
> + */
> +static bool
> +oid_get_description(const struct oid *o, struct oiddescription *od)
> +{
> + int lookup[CTL_MAXNAME + 2];
> + char *newline;
> + size_t odlen;
> +
> + lookup[0] = 0;
> + lookup[1] = 5;
> + memcpy(lookup + 2, o->id, o->len * sizeof(lookup[0]));
> + odlen = sizeof(od->description);
> + if (sysctl(lookup, 2 + o->len, &od->description, &odlen, 0, 0) != 0) {
> + if (errno == ENOENT)
> + return (false);
> + err(1, "sysctl(oiddescr)");
> + }
> +
> + newline = strchr(od->description, '\n');
> + if (newline != NULL)
> + *newline = '\0';
> +
> + return (*od->description != '\0');
> +}
> +
> +/* Prints the description of an OID to a file stream. */
> +static void
> +oiddescription_print(const struct oiddescription *od, FILE *fp)
> +{
> +
> + fprintf(fp, "%s", od->description);
> +}
> +
> +static void
> +oid_print(const struct oid *o, struct oidname *on, bool print_description,
> + FILE *fp)
> +{
> + struct oidformat of;
> + struct oidvalue ov;
> + struct oiddescription od;
> +
> + if (!oid_get_format(o, &of) || !oid_get_value(o, &of, &ov))
> + return;
> + oid_get_name(o, on);
> +
> + /*
> + * Print the line with the description. Prometheus expects a
> + * single unique description for every metric, which cannot be
> + * guaranteed by sysctl if labels are present. Omit the
> + * description if labels are present.
> + */
> + if (print_description && !oidname_has_labels(on) &&
> + oid_get_description(o, &od)) {
> + fprintf(fp, "# HELP ");
> + oidname_print(on, &of, fp);
> + fputc(' ', fp);
> + oiddescription_print(&od, fp);
> + fputc('\n', fp);
> + }
> +
> + /* Print the line with the value. */
> + oidname_print(on, &of, fp);
> + fputc(' ', fp);
> + oidvalue_print(&ov, fp);
> + fputc('\n', fp);
> +}
> +
> +/* Gzip compresses a buffer of memory. */
> +static bool
> +buf_gzip(const char *in, size_t inlen, char *out, size_t *outlen)
> +{
> + z_stream stream = {
> + .next_in = __DECONST(unsigned char *, in),
> + .avail_in = inlen,
> + .next_out = (unsigned char *)out,
> + .avail_out = *outlen,
> + };
> +
> + if (deflateInit2(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
> + MAX_WBITS + 16, 8, Z_DEFAULT_STRATEGY) != Z_OK ||
> + deflate(&stream, Z_FINISH) != Z_STREAM_END) {
> + return (false);
> + }
> + *outlen = stream.total_out;
> + return (deflateEnd(&stream) == Z_OK);
> +}
> +
> +static void
> +usage(void)
> +{
> +
> + fprintf(stderr,
> + "usage: prometheus_sysctl_exporter [-dgh] [prefix ...]\n");
> + exit(1);
> +}
> +
> +int
> +main(int argc, char *argv[])
> +{
> + struct oidname on;
> + char *http_buf;
> + FILE *fp;
> + size_t http_buflen;
> + int ch;
> + bool gzip_mode, http_mode, print_descriptions;
> +
> + /* Parse command line flags. */
> + gzip_mode = http_mode = print_descriptions = false;
> + while ((ch = getopt(argc, argv, "dgh")) != -1) {
> + switch (ch) {
> + case 'd':
> + print_descriptions = true;
> + break;
> + case 'g':
> + gzip_mode = true;
> + break;
> + case 'h':
> + http_mode = true;
> + break;
> + default:
> + usage();
> + }
> + }
> + argc -= optind;
> + argv += optind;
> +
> + /* HTTP output: cache metrics in buffer. */
> + if (http_mode) {
> + fp = open_memstream(&http_buf, &http_buflen);
> + if (fp == NULL)
> + err(1, "open_memstream");
> + } else {
> + fp = stdout;
> + }
> +
> + oidname_init(&on);
> + if (argc == 0) {
> + struct oid o;
> +
> + /* Print all OIDs. */
> + oid_get_root(&o);
> + do {
> + oid_print(&o, &on, print_descriptions, fp);
> + } while (oid_get_next(&o, &o));
> + } else {
> + int i;
> +
> + /* Print only trees provided as arguments. */
> + for (i = 0; i < argc; ++i) {
> + struct oid o, root;
> +
> + oid_get_by_name(&root, argv[i]);
> + o = root;
> + do {
> + oid_print(&o, &on, print_descriptions, fp);
> + } while (oid_get_next(&o, &o) &&
> + oid_is_beneath(&o, &root));
> + }
> + }
> +
> + if (http_mode) {
> + const char *content_encoding = "";
> +
> + if (ferror(fp) || fclose(fp) != 0)
> + err(1, "Cannot generate output");
> +
> + /* Gzip compress the output. */
> + if (gzip_mode) {
> + char *buf;
> + size_t buflen;
> +
> + buflen = http_buflen;
> + buf = malloc(buflen);
> + if (buf == NULL)
> + err(1, "Cannot allocate compression buffer");
> + if (buf_gzip(http_buf, http_buflen, buf, &buflen)) {
> + content_encoding = "Content-Encoding: gzip\r\n";
> + free(http_buf);
> + http_buf = buf;
> + http_buflen = buflen;
> + } else {
> + free(buf);
> + }
> + }
> +
> + /* Print HTTP header and metrics. */
> + dprintf(STDOUT_FILENO,
> + "HTTP/1.1 200 OK\r\n"
> + "Connection: close\r\n"
> + "%s"
> + "Content-Length: %zu\r\n"
> + "Content-Type: text/plain; version=0.0.4\r\n"
> + "\r\n",
> + content_encoding, http_buflen);
> + write(STDOUT_FILENO, http_buf, http_buflen);
> + free(http_buf);
> +
> + /* Drain output. */
> + if (shutdown(STDIN_FILENO, SHUT_WR) == 0) {
> + char buf[1024];
> +
> + while (read(STDIN_FILENO, buf, sizeof(buf)) > 0) {
> + }
> + }
> + }
> + return (0);
> +}
>
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