freebsd-dev/usr.sbin/prometheus_sysctl_exporter/prometheus_sysctl_exporter.c
Alan Somers 982f980b86 prometheus_sysctl_exporter: ignore ENOENT for mibs specified on the CLI
They might belong to kernel modules not currently loaded, or to other
kernel versions.  Ignoring them allows the configuration to be shared
between multiple hosts.

MFC after:	2 weeks
Sponsored by:	Axcient
Reviewed by:	rew
Differential Revision: https://reviews.freebsd.org/D35540
2022-07-24 09:19:46 -06:00

710 lines
16 KiB
C

/*-
* Copyright (c) 2016-2017 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 <ctype.h>
#include <err.h>
#include <errno.h>
#include <math.h>
#include <regex.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#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.
*/
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 bool
oid_get_by_name(struct oid *o, const char *name)
{
o->len = nitems(o->id);
return (sysctlnametomib(name, o->id, &o->len) == 0);
}
/* 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 Celsius. */
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;
}
/* Populates the name and labels of an OID to a buffer. */
static void
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, buf[BUFSIZ];
/* Print the name of the metric. */
snprintf(metric, mlen, "%s", "sysctl");
name = on->names;
label = on->labels;
for (i = 0; i < on->oid.len; ++i) {
if (*label == '\0') {
strlcat(metric, "_", mlen);
while (*name != '\0') {
/* Map unsupported characters to underscores. */
snprintf(buf, sizeof(buf), "%c",
isalnum(*name) ? *name : '_');
strlcat(metric, buf, mlen);
++name;
}
}
name += strlen(name) + 1;
label += strlen(label) + 1;
}
if (oidformat_is_temperature(of))
strlcat(metric, "_celsius", mlen);
else if (oidformat_is_timeval(of))
strlcat(metric, "_seconds", mlen);
/* 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(label[strspn(label,
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789_")] == '\0');
snprintf(buf, sizeof(buf), "%c%s=\"", separator, label);
strlcat(metric, buf, mlen);
while (*name != '\0') {
/* Escape backslashes and double quotes. */
if (*name == '\\' || *name == '"')
strlcat(metric, "\\", mlen);
snprintf(buf, sizeof(buf), "%c", *name++);
strlcat(metric, buf, mlen);
}
strlcat(metric, "\"", mlen);
separator = ',';
}
name += strlen(name) + 1;
label += strlen(label) + 1;
}
if (separator != '{')
strlcat(metric, "}", mlen);
}
/* 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,
bool exclude, bool include, FILE *fp)
{
struct oidformat of;
struct oidvalue ov;
struct oiddescription od;
char metric[BUFSIZ];
bool has_desc;
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;
has_desc = oid_get_description(o, &od);
/*
* Skip metrics with "(LEGACY)" in the name. It's used by several
* redundant ZFS sysctls whose names alias with the non-legacy versions.
*/
if (has_desc && strnstr(od.description, "(LEGACY)", BUFSIZ) != NULL)
return;
/*
* 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) && has_desc) {
fprintf(fp, "# HELP ");
fprintf(fp, "%s", metric);
fputc(' ', fp);
oiddescription_print(&od, fp);
fputc('\n', fp);
}
/* Print the line with the value. */
fprintf(fp, "%s", metric);
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, "%s",
"usage: prometheus_sysctl_exporter [-dgh] [-e pattern] [-i pattern]\n"
"\t[prefix ...]\n");
exit(1);
}
int
main(int argc, char *argv[])
{
struct oidname on;
char *http_buf;
FILE *fp;
size_t http_buflen;
int ch, error;
bool exclude, include, gzip_mode, http_mode, print_descriptions;
char errbuf[BUFSIZ];
/* Parse command line flags. */
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();
}
}
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, exclude, include, 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;
if (!oid_get_by_name(&root, argv[i])) {
/*
* Ignore trees provided as arguments that
* can't be found. They might belong, for
* example, to kernel modules not currently
* loaded.
*/
continue;
}
o = root;
do {
oid_print(&o, &on, print_descriptions, exclude, include, 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);
}