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prometheus_sysctl_exporter(8): filter output using a regex

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Add two options, -i and -e, for filtering prometheus metrics.

Each option takes a regular expression as an argument. The provided
regex will be tested against the prometheus metric name.

The -i option includes metrics matching the given regex.
The -e option excludes metrics matching the given regex.

Sponsored by:   Modirum MDPay
Sponsored by:   Klara Inc.
Reviewed by:	0mp, debdrup
Differential Revision:	https://reviews.freebsd.org/D32269
This commit is contained in:
Robert Wing 2021-10-07 17:00:27 -08:00
parent b5cadc643e
commit 8ff2b52241
2 changed files with 80 additions and 26 deletions
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18
usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.8
View File

@ -22,7 +22,7 @@
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.Dd December 18, 2016
.Dd October 7, 2021
.Dt PROMETHEUS_SYSCTL_EXPORTER 8
.Os
.Sh NAME
@ -31,6 +31,8 @@
.Sh SYNOPSIS
.Nm prometheus_sysctl_exporter
.Op Fl dgh
.Op Fl e Ar pattern
.Op Fl i Ar pattern
.Op Ar prefix ...
.Sh DESCRIPTION
Prometheus is a monitoring system that gathers metrics from its targets
@ -74,12 +76,26 @@ The following options are available:
.Bl -tag -width indent
.It Fl d
Print descriptions of metrics when available.
.It Fl e Ar pattern
Same as
.Fl i ,
except exclude metrics that match
.Ar pattern .
.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 .
.It Fl i Ar pattern
If specified, include metrics that match
.Ar pattern .
The format of
.Ar pattern
is to be a regular expression as described in
.Xr re_format 7 .
The provided regular expression is tested against the Prometheus
metric name.
.El
.Sh SEE ALSO
.Xr cron 8 ,

88
usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.c
View File

@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <err.h>
#include <errno.h>
#include <math.h>
#include <regex.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
@ -44,6 +45,10 @@ __FBSDID("$FreeBSD$");
#include <unistd.h>
#include <zlib.h>
/* Regular expressions for filtering output. */
static regex_t inc_regex;
static regex_t exc_regex;
/*
* Cursor for iterating over all of the system's sysctl OIDs.
*/
@ -370,25 +375,27 @@ oid_get_name(const struct oid *o, struct oidname *on)
on->oid = *o;
}
/* Prints the name and labels of an OID to a file stream. */
/* Populates the name and labels of an OID to a buffer. */
static void
oidname_print(const struct oidname *on, const struct oidformat *of,
FILE *fp)
oid_get_metric(const struct oidname *on, const struct oidformat *of,
char *metric, size_t mlen)
{
const char *name, *label;
size_t i;
char separator;
char separator, buf[BUFSIZ];
/* Print the name of the metric. */
fprintf(fp, "sysctl");
snprintf(metric, mlen, "%s", "sysctl");
name = on->names;
label = on->labels;
for (i = 0; i < on->oid.len; ++i) {
if (*label == '\0') {
fputc('_', fp);
strlcat(metric, "_", mlen);
while (*name != '\0') {
/* Map unsupported characters to underscores. */
fputc(isalnum(*name) ? *name : '_', fp);
snprintf(buf, sizeof(buf), "%c",
isalnum(*name) ? *name : '_');
strlcat(metric, buf, mlen);
++name;
}
}
@ -396,9 +403,9 @@ oidname_print(const struct oidname *on, const struct oidformat *of,
label += strlen(label) + 1;
}
if (oidformat_is_temperature(of))
fprintf(fp, "_celcius");
strlcat(metric, "_celcius", mlen);
else if (oidformat_is_timeval(of))
fprintf(fp, "_seconds");
strlcat(metric, "_seconds", mlen);
/* Print the labels of the metric. */
name = on->names;
@ -410,21 +417,23 @@ oidname_print(const struct oidname *on, const struct oidformat *of,
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789_")] == '\0');
fprintf(fp, "%c%s=\"", separator, label);
snprintf(buf, sizeof(buf), "%c%s=\"", separator, label);
strlcat(metric, buf, mlen);
while (*name != '\0') {
/* Escape backslashes and double quotes. */
if (*name == '\\' || *name == '"')
fputc('\\', fp);
fputc(*name++, fp);
strlcat(metric, "\\", mlen);
snprintf(buf, sizeof(buf), "%c", *name++);
strlcat(metric, buf, mlen);
}
fputc('"', fp);
strlcat(metric, "\"", mlen);
separator = ',';
}
name += strlen(name) + 1;
label += strlen(label) + 1;
}
if (separator != '{')
fputc('}', fp);
strlcat(metric, "}", mlen);
}
/* Returns whether the OID name has any labels associated to it. */
@ -483,16 +492,25 @@ oiddescription_print(const struct oiddescription *od, FILE *fp)
static void
oid_print(const struct oid *o, struct oidname *on, bool print_description,
FILE *fp)
bool exclude, bool include, FILE *fp)
{
struct oidformat of;
struct oidvalue ov;
struct oiddescription od;
char metric[BUFSIZ];
if (!oid_get_format(o, &of) || !oid_get_value(o, &of, &ov))
return;
oid_get_name(o, on);
oid_get_metric(on, &of, metric, sizeof(metric));
if (exclude && regexec(&exc_regex, metric, 0, NULL, 0) == 0)
return;
if (include && regexec(&inc_regex, metric, 0, NULL, 0) != 0)
return;
/*
* Print the line with the description. Prometheus expects a
* single unique description for every metric, which cannot be
@ -502,14 +520,14 @@ oid_print(const struct oid *o, struct oidname *on, bool print_description,
if (print_description && !oidname_has_labels(on) &&
oid_get_description(o, &od)) {
fprintf(fp, "# HELP ");
oidname_print(on, &of, fp);
fprintf(fp, "%s", metric);
fputc(' ', fp);
oiddescription_print(&od, fp);
fputc('\n', fp);
}
/* Print the line with the value. */
oidname_print(on, &of, fp);
fprintf(fp, "%s", metric);
fputc(' ', fp);
oidvalue_print(&ov, fp);
fputc('\n', fp);
@ -539,8 +557,9 @@ static void
usage(void)
{
fprintf(stderr,
"usage: prometheus_sysctl_exporter [-dgh] [prefix ...]\n");
fprintf(stderr, "%s",
"usage: prometheus_sysctl_exporter [-dgh] [-e pattern] [-i pattern]\n"
"\t[prefix ...]\n");
exit(1);
}
@ -551,22 +570,41 @@ main(int argc, char *argv[])
char *http_buf;
FILE *fp;
size_t http_buflen;
int ch;
bool gzip_mode, http_mode, print_descriptions;
int ch, error;
bool exclude, include, gzip_mode, http_mode, print_descriptions;
char errbuf[BUFSIZ];
/* Parse command line flags. */
gzip_mode = http_mode = print_descriptions = false;
while ((ch = getopt(argc, argv, "dgh")) != -1) {
include = exclude = gzip_mode = http_mode = print_descriptions = false;
while ((ch = getopt(argc, argv, "de:ghi:")) != -1) {
switch (ch) {
case 'd':
print_descriptions = true;
break;
case 'e':
error = regcomp(&exc_regex, optarg, REG_EXTENDED);
if (error != 0) {
regerror(error, &exc_regex, errbuf, sizeof(errbuf));
errx(1, "bad regular expression '%s': %s",
optarg, errbuf);
}
exclude = true;
break;
case 'g':
gzip_mode = true;
break;
case 'h':
http_mode = true;
break;
case 'i':
error = regcomp(&inc_regex, optarg, REG_EXTENDED);
if (error != 0) {
regerror(error, &inc_regex, errbuf, sizeof(errbuf));
errx(1, "bad regular expression '%s': %s",
optarg, errbuf);
}
include = true;
break;
default:
usage();
}
@ -590,7 +628,7 @@ main(int argc, char *argv[])
/* Print all OIDs. */
oid_get_root(&o);
do {
oid_print(&o, &on, print_descriptions, fp);
oid_print(&o, &on, print_descriptions, exclude, include, fp);
} while (oid_get_next(&o, &o));
} else {
int i;
@ -602,7 +640,7 @@ main(int argc, char *argv[])
oid_get_by_name(&root, argv[i]);
o = root;
do {
oid_print(&o, &on, print_descriptions, fp);
oid_print(&o, &on, print_descriptions, exclude, include, fp);
} while (oid_get_next(&o, &o) &&
oid_is_beneath(&o, &root));
}