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MEDIUM: promex: Add a registration mechanism to support modules 

In this patch we add a registration mechanism for modules. To do so, a
module must defined the "promex_module" structure. The dump itself will be
based on 2 contexts. One for all the dump and another one for each metric
time-series. These contexts are used as restart points when the dump is
interrupted.

Modules must also implement 6 callback functions:

  * start_metric_dump(): It is an optional callback function. If defined, it
                         is responsible to initialize the dump context use
                         as the first restart point.

  * stop_metric_dump(): It is an optional callback function. If defined, it
                        is responsible to deinit the dump context.

  * metric_info(): This one is mandatory. It returns the info about the
                   metric: name, type and flags and descrition.

  * start_ts(): This one is mandatory, it initializes the context for a time
                series for a given metric. This context is the second
                restart point.

  * next_ts(): This one is mandatory. It interates on time series for a
               given metrics. It is also responsible to handle end of a
               time series and deinit the context.

  * fill_ts(): It fills info on the time series for a given metric : the
               labels and the value.

In addition, a module must set its name and declare the number of metrics is
exposed.
This commit is contained in:
Christopher Faulet 2024-01-30 07:34:54 +01:00
parent 65db9f2a01
commit eb2128723a
3 changed files with 115 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Makefile
View File

@ -663,6 +663,7 @@ endif # USE_LUA
ifneq ($(USE_PROMEX),)
OPTIONS_OBJS += addons/promex/service-prometheus.o
PROMEX_CFLAGS = -Iaddons/promex/include
endif
ifneq ($(USE_DEVICEATLAS),)

104
addons/promex/include/promex/promex.h Normal file
View File

@ -0,0 +1,104 @@
/*
* include/promex/promex.h
* This file contains definitions, macros and inline functions dedicated to
* the prometheus exporter for HAProxy.
*
* Copyright 2024 Christopher Faulet <cfaulet@haproxy.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _PROMEX_PROMEX_H
#define _PROMEX_PROMEX_H
#include <import/ist.h>
#include <haproxy/api-t.h>
#include <haproxy/list-t.h>
/* The max number of labels per metric */
#define PROMEX_MAX_LABELS 8
/* Promtheus metric type (gauge or counter) */
enum promex_mt_type {
PROMEX_MT_GAUGE = 1,
PROMEX_MT_COUNTER = 2,
};
/* Describe a prometheus metric */
struct promex_metric {
struct ist n; /* The metric name */
enum promex_mt_type type; /* The metric type (gauge or counter) */
unsigned int flags; /* PROMEX_FL_* flags */
};
/* Describe a prometheus metric label. It is just a key/value pair */
struct promex_label {
struct ist name;
struct ist value;
};
/* Entity used to expose custom metrics on HAProxy.
*
* * start_metric_dump(): It is an optional callback function. If defined, it
* is responsible to initialize the dump context use
* as the first restart point.
*
* * stop_metric_dump(): It is an optional callback function. If defined, it
* is responsible to deinit the dump context.
*
* * metric_info(): This one is mandatory. It returns the info about the
* metric: name, type and flags and descrition.
*
* * start_ts(): This one is mandatory, it initializes the context for a time
* series for a given metric. This context is the second
* restart point.
*
* * next_ts(): This one is mandatory. It interates on time series for a
* given metrics. It is also responsible to handle end of a
* time series and deinit the context.
*
* * fill_ts(): It fills info on the time series for a given metric : the
* labels and the value.
*/
struct promex_module {
struct list list;
struct ist name; /* The promex module name */
int (*metric_info)(unsigned int id, /* Return info for the given id */
struct promex_metric *metric,
struct ist *desc);
void *(*start_metrics_dump)(); /* Start a dump (may be NULL) */
void (*stop_metrics_dump)(void *ctx); /* Stop a dump (may be NULL) */
void *(*start_ts)(void *ctx, unsigned int id); /* Start a time series for the given metric */
void *(*next_ts)(void *ctx, void *ts_ctx, unsigned int id); /* move to the next time series for the given metric */
int (*fill_ts)(void *ctx, void *ts_ctx, unsigned int id, /* fill the time series for the given metric */
struct promex_label *labels, struct field *field);
size_t nb_metrics; /* # of metrics */
};
extern struct list promex_module_list;
void promex_register_module(struct promex_module *m);
#endif /* _PROMEX_PROMEX_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/

32
addons/promex/service-prometheus.c
View File

@ -39,6 +39,8 @@
#include <haproxy/tools.h>
#include <haproxy/version.h>
#include <promex/promex.h>
/* Prometheus exporter applet states (appctx->st0) */
enum {
PROMEX_ST_INIT = 0, /* initialized */
@ -90,12 +92,6 @@ struct promex_ctx {
int obj_state; /* current state among PROMEX_{FRONT|BACK|SRV|LI}_STATE_* */
};
/* Promtheus metric type (gauge or counter) */
enum promex_mt_type {
PROMEX_MT_GAUGE = 1,
PROMEX_MT_COUNTER = 2,
};
/* The max length for metrics name. It is a hard limit but it should be
* enough.
*/
@ -107,22 +103,6 @@ enum promex_mt_type {
*/
#define PROMEX_MAX_METRIC_LENGTH 512
/* The max number of labels per metric */
#define PROMEX_MAX_LABELS 8
/* Describe a prometheus metric */
struct promex_metric {
const struct ist n; /* The metric name */
enum promex_mt_type type; /* The metric type (gauge or counter) */
unsigned int flags; /* PROMEX_FL_* flags */
};
/* Describe a prometheus metric label. It is just a key/value pair */
struct promex_label {
struct ist name;
struct ist value;
};
/* Global metrics */
const struct promex_metric promex_global_metrics[INF_TOTAL_FIELDS] = {
//[INF_NAME] ignored
@ -410,6 +390,14 @@ const struct ist promex_srv_st[PROMEX_SRV_STATE_COUNT] = {
[PROMEX_SRV_STATE_NOLB] = IST("NOLB"),
};
struct list promex_module_list = LIST_HEAD_INIT(promex_module_list);
void promex_register_module(struct promex_module *m)
{
LIST_APPEND(&promex_module_list, &m->list);
}
/* Return the server status. */
enum promex_srv_state promex_srv_status(struct server *sv)
{