43a60fc980d4ef8f0332e239ae09e4737705870a
1 /**
2 * collectd - src/write_prometheus.c
3 * Copyright (C) 2016 Florian octo Forster
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included in
13 * all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 *
23 * Authors:
24 * Florian octo Forster <octo at collectd.org>
25 */
27 #include "collectd.h"
29 #include "common.h"
30 #include "plugin.h"
31 #include "utils_avltree.h"
32 #include "utils_complain.h"
33 #include "utils_time.h"
35 #include "prometheus.pb-c.h"
37 #include <microhttpd.h>
39 #ifndef PROMETHEUS_DEFAULT_STALENESS_DELTA
40 #define PROMETHEUS_DEFAULT_STALENESS_DELTA TIME_T_TO_CDTIME_T(300)
41 #endif
43 #define VARINT_UINT32_BYTES 5
45 #define CONTENT_TYPE_PROTO \
46 "application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; " \
47 "encoding=delimited"
48 #define CONTENT_TYPE_TEXT "text/plain; version=0.0.4"
50 static c_avl_tree_t *metrics;
51 static pthread_mutex_t metrics_lock = PTHREAD_MUTEX_INITIALIZER;
53 static unsigned short httpd_port = 9103;
54 static struct MHD_Daemon *httpd;
56 static cdtime_t staleness_delta = PROMETHEUS_DEFAULT_STALENESS_DELTA;
58 /* Unfortunately, protoc-c doesn't export it's implementation of varint, so we
59 * need to implement our own. */
60 static size_t varint(uint8_t buffer[static VARINT_UINT32_BYTES],
61 uint32_t value) {
62 for (size_t i = 0; i < VARINT_UINT32_BYTES; i++) {
63 buffer[i] = (uint8_t)(value & 0x7f);
64 value >>= 7;
66 if (value == 0)
67 return i + 1;
69 buffer[i] |= 0x80;
70 }
72 return 0;
73 }
75 /* format_protobuf iterates over all metric families in "metrics" and adds them
76 * to a buffer in ProtoBuf format. It prefixes each protobuf with its encoded
77 * size, the so called "delimited" format. */
78 static void format_protobuf(ProtobufCBuffer *buffer) {
79 pthread_mutex_lock(&metrics_lock);
81 char *unused_name;
82 Io__Prometheus__Client__MetricFamily *fam;
83 c_avl_iterator_t *iter = c_avl_get_iterator(metrics);
84 while (c_avl_iterator_next(iter, (void *)&unused_name, (void *)&fam) == 0) {
85 /* Prometheus uses a message length prefix to determine where one
86 * MetricFamily ends and the next begins. This delimiter is encoded as a
87 * "varint", which is common in Protobufs. */
88 uint8_t delim[VARINT_UINT32_BYTES] = {0};
89 size_t delim_len = varint(
90 delim,
91 (uint32_t)io__prometheus__client__metric_family__get_packed_size(fam));
92 buffer->append(buffer, delim_len, delim);
94 io__prometheus__client__metric_family__pack_to_buffer(fam, buffer);
95 }
96 c_avl_iterator_destroy(iter);
98 pthread_mutex_unlock(&metrics_lock);
99 }
101 /* format_labels formats a metric's labels in Prometheus-compatible format. This
102 * format looks like this:
103 *
104 * key0="value0",key1="value1"
105 */
106 static char *format_labels(char *buffer, size_t buffer_size,
107 Io__Prometheus__Client__Metric const *m) {
108 /* our metrics always have at least one and at most three labels. */
109 assert(m->n_label >= 1);
110 assert(m->n_label <= 3);
112 #define LABEL_BUFFER_SIZE (2 * DATA_MAX_NAME_LEN + 4)
114 char *labels[3] = {
115 (char[LABEL_BUFFER_SIZE]){0}, (char[LABEL_BUFFER_SIZE]){0},
116 (char[LABEL_BUFFER_SIZE]){0},
117 };
119 for (size_t i = 0; i < m->n_label; i++)
120 ssnprintf(labels[i], LABEL_BUFFER_SIZE, "%s=\"%s\"", m->label[i]->name,
121 m->label[i]->value);
123 strjoin(buffer, buffer_size, labels, m->n_label, ",");
124 return buffer;
125 }
127 /* format_protobuf iterates over all metric families in "metrics" and adds them
128 * to a buffer in plain text format. */
129 static void format_text(ProtobufCBuffer *buffer) {
130 pthread_mutex_lock(&metrics_lock);
132 char *unused_name;
133 Io__Prometheus__Client__MetricFamily *fam;
134 c_avl_iterator_t *iter = c_avl_get_iterator(metrics);
135 while (c_avl_iterator_next(iter, (void *)&unused_name, (void *)&fam) == 0) {
136 char line[1024]; /* 4x DATA_MAX_NAME_LEN? */
138 ssnprintf(line, sizeof(line), "# HELP %s %s\n", fam->name, fam->help);
139 buffer->append(buffer, strlen(line), (uint8_t *)line);
141 ssnprintf(line, sizeof(line), "# TYPE %s %s\n", fam->name,
142 (fam->type == IO__PROMETHEUS__CLIENT__METRIC_TYPE__GAUGE)
143 ? "gauge"
144 : "counter");
145 buffer->append(buffer, strlen(line), (uint8_t *)line);
147 for (size_t i = 0; i < fam->n_metric; i++) {
148 Io__Prometheus__Client__Metric *m = fam->metric[i];
150 char labels[1024];
152 char timestamp_ms[24] = "";
153 if (m->has_timestamp_ms)
154 ssnprintf(timestamp_ms, sizeof(timestamp_ms), " %" PRIi64,
155 m->timestamp_ms);
157 if (fam->type == IO__PROMETHEUS__CLIENT__METRIC_TYPE__GAUGE)
158 ssnprintf(line, sizeof(line), "%s{%s} " GAUGE_FORMAT "%s\n", fam->name,
159 format_labels(labels, sizeof(labels), m), m->gauge->value,
160 timestamp_ms);
161 else /* if (fam->type == IO__PROMETHEUS__CLIENT__METRIC_TYPE__COUNTER) */
162 ssnprintf(line, sizeof(line), "%s{%s} %.0f%s\n", fam->name,
163 format_labels(labels, sizeof(labels), m), m->counter->value,
164 timestamp_ms);
166 buffer->append(buffer, strlen(line), (uint8_t *)line);
167 }
168 }
169 c_avl_iterator_destroy(iter);
171 char server[1024];
172 ssnprintf(server, sizeof(server), "\n# collectd/write_prometheus %s at %s\n",
173 PACKAGE_VERSION, hostname_g);
174 buffer->append(buffer, strlen(server), (uint8_t *)server);
176 pthread_mutex_unlock(&metrics_lock);
177 }
179 /* http_handler is the callback called by the microhttpd library. It essentially
180 * handles all HTTP request aspects and creates an HTTP response. */
181 static int http_handler(void *cls, struct MHD_Connection *connection,
182 const char *url, const char *method,
183 const char *version, const char *upload_data,
184 size_t *upload_data_size, void **connection_state) {
185 if (strcmp(method, MHD_HTTP_METHOD_GET) != 0) {
186 return MHD_NO;
187 }
189 /* On the first call for each connection, return without anything further.
190 * Apparently not everything has been initialized yet or so; the docs are not
191 * very specific on the issue. */
192 if (*connection_state == NULL) {
193 /* set to a random non-NULL pointer. */
194 *connection_state = &(int){42};
195 return MHD_YES;
196 }
198 char const *accept = MHD_lookup_connection_value(connection, MHD_HEADER_KIND,
199 MHD_HTTP_HEADER_ACCEPT);
200 _Bool want_proto =
201 (accept != NULL) &&
202 (strstr(accept, "application/vnd.google.protobuf") != NULL);
204 uint8_t scratch[4096] = {0};
205 ProtobufCBufferSimple simple = PROTOBUF_C_BUFFER_SIMPLE_INIT(scratch);
206 ProtobufCBuffer *buffer = (ProtobufCBuffer *)&simple;
208 if (want_proto)
209 format_protobuf(buffer);
210 else
211 format_text(buffer);
213 struct MHD_Response *res =
214 #if defined(MHD_VERSION) && MHD_VERSION >= 0x00090500
215 MHD_create_response_from_buffer(
216 simple.len, simple.data, MHD_RESPMEM_MUST_COPY);
217 #else
218 MHD_create_response_from_data(
219 simple.len, simple.data, /* must_free = */ 0, /* must_copy = */ 1);
220 #endif
221 MHD_add_response_header(res, MHD_HTTP_HEADER_CONTENT_TYPE,
222 want_proto ? CONTENT_TYPE_PROTO : CONTENT_TYPE_TEXT);
224 int status = MHD_queue_response(connection, MHD_HTTP_OK, res);
226 MHD_destroy_response(res);
227 PROTOBUF_C_BUFFER_SIMPLE_CLEAR(&simple);
228 return status;
229 }
231 /*
232 * Functions for manipulating the global state in "metrics". This is organized
233 * in two tiers: the global "metrics" tree holds "metric families", which are
234 * identified by a name (a string). Each metric family has one or more
235 * "metrics", which are identified by a unique set of key-value-pairs. For
236 * example:
237 *
238 * collectd_cpu_total
239 * {cpu="0",type="idle"}
240 * {cpu="0",type="user"}
241 * ...
242 * collectd_memory
243 * {memory="used"}
244 * {memory="free"}
245 * ...
246 * {{{ */
247 /* label_pair_destroy frees the memory used by a label pair. */
248 static void label_pair_destroy(Io__Prometheus__Client__LabelPair *msg) {
249 if (msg == NULL)
250 return;
252 sfree(msg->name);
253 sfree(msg->value);
255 sfree(msg);
256 }
258 /* label_pair_clone allocates and initializes a new label pair. */
259 static Io__Prometheus__Client__LabelPair *
260 label_pair_clone(Io__Prometheus__Client__LabelPair const *orig) {
261 Io__Prometheus__Client__LabelPair *copy = calloc(1, sizeof(*copy));
262 if (copy == NULL)
263 return NULL;
264 io__prometheus__client__label_pair__init(copy);
266 copy->name = strdup(orig->name);
267 copy->value = strdup(orig->value);
268 if ((copy->name == NULL) || (copy->value == NULL)) {
269 label_pair_destroy(copy);
270 return NULL;
271 }
273 return copy;
274 }
276 /* metric_destroy frees the memory used by a metric. */
277 static void metric_destroy(Io__Prometheus__Client__Metric *msg) {
278 if (msg == NULL)
279 return;
281 for (size_t i = 0; i < msg->n_label; i++) {
282 label_pair_destroy(msg->label[i]);
283 }
284 sfree(msg->label);
286 sfree(msg->gauge);
287 sfree(msg->counter);
289 sfree(msg);
290 }
292 /* metric_cmp compares two metrics. It's prototype makes it easy to use with
293 * qsort(3) and bsearch(3). */
294 static int metric_cmp(void const *a, void const *b) {
295 Io__Prometheus__Client__Metric const *m_a =
296 *((Io__Prometheus__Client__Metric **)a);
297 Io__Prometheus__Client__Metric const *m_b =
298 *((Io__Prometheus__Client__Metric **)b);
300 if (m_a->n_label < m_b->n_label)
301 return -1;
302 else if (m_a->n_label > m_b->n_label)
303 return 1;
305 /* Prometheus does not care about the order of labels. All labels in this
306 * plugin are created by METRIC_ADD_LABELS(), though, and therefore always
307 * appear in the same order. We take advantage of this and simplify the check
308 * by making sure all labels are the same in each position.
309 *
310 * We also only need to check the label values, because the label names are
311 * the same for all metrics in a metric family.
312 *
313 * 3 labels:
314 * [0] $plugin="$plugin_instance" => $plugin is the same within a family
315 * [1] type="$type_instance" => "type" is a static string
316 * [2] instance="$host" => "instance" is a static string
317 *
318 * 2 labels, variant 1:
319 * [0] $plugin="$plugin_instance" => $plugin is the same within a family
320 * [1] instance="$host" => "instance" is a static string
321 *
322 * 2 labels, variant 2:
323 * [0] $plugin="$type_instance" => $plugin is the same within a family
324 * [1] instance="$host" => "instance" is a static string
325 *
326 * 1 label:
327 * [1] instance="$host" => "instance" is a static string
328 */
329 for (size_t i = 0; i < m_a->n_label; i++) {
330 int status = strcmp(m_a->label[i]->value, m_b->label[i]->value);
331 if (status != 0)
332 return status;
334 #if COLLECT_DEBUG
335 assert(strcmp(m_a->label[i]->name, m_b->label[i]->name) == 0);
336 #endif
337 }
339 return 0;
340 }
342 #define METRIC_INIT \
343 &(Io__Prometheus__Client__Metric) { \
344 .label = \
345 (Io__Prometheus__Client__LabelPair *[]){ \
346 &(Io__Prometheus__Client__LabelPair){ \
347 .name = NULL, \
348 }, \
349 &(Io__Prometheus__Client__LabelPair){ \
350 .name = NULL, \
351 }, \
352 &(Io__Prometheus__Client__LabelPair){ \
353 .name = NULL, \
354 }, \
355 }, \
356 .n_label = 0, \
357 }
359 #define METRIC_ADD_LABELS(m, vl) \
360 do { \
361 if (strlen((vl)->plugin_instance) != 0) { \
362 (m)->label[(m)->n_label]->name = (char *)(vl)->plugin; \
363 (m)->label[(m)->n_label]->value = (char *)(vl)->plugin_instance; \
364 (m)->n_label++; \
365 } \
366 \
367 if (strlen((vl)->type_instance) != 0) { \
368 (m)->label[(m)->n_label]->name = "type"; \
369 if (strlen((vl)->plugin_instance) == 0) \
370 (m)->label[(m)->n_label]->name = (char *)(vl)->plugin; \
371 (m)->label[(m)->n_label]->value = (char *)(vl)->type_instance; \
372 (m)->n_label++; \
373 } \
374 \
375 (m)->label[(m)->n_label]->name = "instance"; \
376 (m)->label[(m)->n_label]->value = (char *)(vl)->host; \
377 (m)->n_label++; \
378 } while (0)
380 /* metric_clone allocates and initializes a new metric based on orig. */
381 static Io__Prometheus__Client__Metric *
382 metric_clone(Io__Prometheus__Client__Metric const *orig) {
383 Io__Prometheus__Client__Metric *copy = calloc(1, sizeof(*copy));
384 if (copy == NULL)
385 return NULL;
386 io__prometheus__client__metric__init(copy);
388 copy->n_label = orig->n_label;
389 copy->label = calloc(copy->n_label, sizeof(*copy->label));
390 if (copy->label == NULL) {
391 sfree(copy);
392 return NULL;
393 }
395 for (size_t i = 0; i < copy->n_label; i++) {
396 copy->label[i] = label_pair_clone(orig->label[i]);
397 if (copy->label[i] == NULL) {
398 metric_destroy(copy);
399 return NULL;
400 }
401 }
403 return copy;
404 }
406 /* metric_update stores the new value and timestamp in m. */
407 static int metric_update(Io__Prometheus__Client__Metric *m, value_t value,
408 int ds_type, cdtime_t t, cdtime_t interval) {
409 if (ds_type == DS_TYPE_GAUGE) {
410 sfree(m->counter);
411 if (m->gauge == NULL) {
412 m->gauge = calloc(1, sizeof(*m->gauge));
413 if (m->gauge == NULL)
414 return ENOMEM;
415 io__prometheus__client__gauge__init(m->gauge);
416 }
418 m->gauge->value = (double)value.gauge;
419 m->gauge->has_value = 1;
420 } else { /* not gauge */
421 sfree(m->gauge);
422 if (m->counter == NULL) {
423 m->counter = calloc(1, sizeof(*m->counter));
424 if (m->counter == NULL)
425 return ENOMEM;
426 io__prometheus__client__counter__init(m->counter);
427 }
429 switch (ds_type) {
430 case DS_TYPE_ABSOLUTE:
431 m->counter->value = (double)value.absolute;
432 break;
433 case DS_TYPE_COUNTER:
434 m->counter->value = (double)value.counter;
435 break;
436 default:
437 m->counter->value = (double)value.derive;
438 break;
439 }
440 m->counter->has_value = 1;
441 }
443 /* Prometheus has a globally configured timeout after which metrics are
444 * considered stale. This causes problems when metrics have an interval
445 * exceeding that limit. We emulate the behavior of "pushgateway" and *not*
446 * send a timestamp value – Prometheus will fill in the current time. */
447 if (interval <= staleness_delta) {
448 m->timestamp_ms = CDTIME_T_TO_MS(t);
449 m->has_timestamp_ms = 1;
450 } else {
451 static c_complain_t long_metric = C_COMPLAIN_INIT_STATIC;
452 c_complain(
453 LOG_NOTICE, &long_metric,
454 "write_prometheus plugin: You have metrics with an interval exceeding "
455 "\"StalenessDelta\" setting (%.3fs). This is suboptimal, please check "
456 "the collectd.conf(5) manual page to understand what's going on.",
457 CDTIME_T_TO_DOUBLE(staleness_delta));
459 m->timestamp_ms = 0;
460 m->has_timestamp_ms = 0;
461 }
463 return 0;
464 }
466 /* metric_family_add_metric adds m to the metric list of fam. */
467 static int metric_family_add_metric(Io__Prometheus__Client__MetricFamily *fam,
468 Io__Prometheus__Client__Metric *m) {
469 Io__Prometheus__Client__Metric **tmp =
470 realloc(fam->metric, (fam->n_metric + 1) * sizeof(*fam->metric));
471 if (tmp == NULL)
472 return ENOMEM;
473 fam->metric = tmp;
475 fam->metric[fam->n_metric] = m;
476 fam->n_metric++;
478 /* Sort the metrics so that lookup is fast. */
479 qsort(fam->metric, fam->n_metric, sizeof(*fam->metric), metric_cmp);
481 return 0;
482 }
484 /* metric_family_delete_metric looks up and deletes the metric corresponding to
485 * vl. */
486 static int
487 metric_family_delete_metric(Io__Prometheus__Client__MetricFamily *fam,
488 value_list_t const *vl) {
489 Io__Prometheus__Client__Metric *key = METRIC_INIT;
490 METRIC_ADD_LABELS(key, vl);
492 size_t i;
493 for (i = 0; i < fam->n_metric; i++) {
494 if (metric_cmp(&key, &fam->metric[i]) == 0)
495 break;
496 }
498 if (i >= fam->n_metric)
499 return ENOENT;
501 metric_destroy(fam->metric[i]);
502 if ((fam->n_metric - 1) > i)
503 memmove(&fam->metric[i], &fam->metric[i + 1],
504 ((fam->n_metric - 1) - i) * sizeof(fam->metric[i]));
505 fam->n_metric--;
507 Io__Prometheus__Client__Metric **tmp =
508 realloc(fam->metric, fam->n_metric * sizeof(*fam->metric));
509 if ((tmp != NULL) || (fam->n_metric == 0))
510 fam->metric = tmp;
512 return 0;
513 }
515 /* metric_family_get_metric looks up the matching metric in a metric family,
516 * allocating it if necessary. */
517 static Io__Prometheus__Client__Metric *
518 metric_family_get_metric(Io__Prometheus__Client__MetricFamily *fam,
519 value_list_t const *vl) {
520 Io__Prometheus__Client__Metric *key = METRIC_INIT;
521 METRIC_ADD_LABELS(key, vl);
523 /* Metrics are sorted in metric_family_add_metric() so that we can do a binary
524 * search here. */
525 Io__Prometheus__Client__Metric **m = bsearch(
526 &key, fam->metric, fam->n_metric, sizeof(*fam->metric), metric_cmp);
528 if (m != NULL) {
529 return *m;
530 }
532 Io__Prometheus__Client__Metric *new_metric = metric_clone(key);
533 if (new_metric == NULL)
534 return NULL;
536 DEBUG("write_prometheus plugin: created new metric in family");
537 int status = metric_family_add_metric(fam, new_metric);
538 if (status != 0) {
539 metric_destroy(new_metric);
540 return NULL;
541 }
543 return new_metric;
544 }
546 /* metric_family_update looks up the matching metric in a metric family,
547 * allocating it if necessary, and updates the metric to the latest value. */
548 static int metric_family_update(Io__Prometheus__Client__MetricFamily *fam,
549 data_set_t const *ds, value_list_t const *vl,
550 size_t ds_index) {
551 Io__Prometheus__Client__Metric *m = metric_family_get_metric(fam, vl);
552 if (m == NULL)
553 return -1;
555 return metric_update(m, vl->values[ds_index], ds->ds[ds_index].type, vl->time,
556 vl->interval);
557 }
559 /* metric_family_destroy frees the memory used by a metric family. */
560 static void metric_family_destroy(Io__Prometheus__Client__MetricFamily *msg) {
561 if (msg == NULL)
562 return;
564 sfree(msg->name);
565 sfree(msg->help);
567 for (size_t i = 0; i < msg->n_metric; i++) {
568 metric_destroy(msg->metric[i]);
569 }
570 sfree(msg->metric);
572 sfree(msg);
573 }
575 /* metric_family_create allocates and initializes a new metric family. */
576 static Io__Prometheus__Client__MetricFamily *
577 metric_family_create(char *name, data_set_t const *ds, value_list_t const *vl,
578 size_t ds_index) {
579 Io__Prometheus__Client__MetricFamily *msg = calloc(1, sizeof(*msg));
580 if (msg == NULL)
581 return NULL;
582 io__prometheus__client__metric_family__init(msg);
584 msg->name = name;
586 char help[1024];
587 ssnprintf(
588 help, sizeof(help),
589 "write_prometheus plugin: '%s' Type: '%s', Dstype: '%s', Dsname: '%s'",
590 vl->plugin, vl->type, DS_TYPE_TO_STRING(ds->ds[ds_index].type),
591 ds->ds[ds_index].name);
592 msg->help = strdup(help);
594 msg->type = (ds->ds[ds_index].type == DS_TYPE_GAUGE)
595 ? IO__PROMETHEUS__CLIENT__METRIC_TYPE__GAUGE
596 : IO__PROMETHEUS__CLIENT__METRIC_TYPE__COUNTER;
597 msg->has_type = 1;
599 return msg;
600 }
602 /* metric_family_name creates a metric family's name from a data source. This is
603 * done in the same way as done by the "collectd_exporter" for best possible
604 * compatibility. In essence, the plugin, type and data source name go in the
605 * metric family name, while hostname, plugin instance and type instance go into
606 * the labels of a metric. */
607 static char *metric_family_name(data_set_t const *ds, value_list_t const *vl,
608 size_t ds_index) {
609 char const *fields[5] = {"collectd"};
610 size_t fields_num = 1;
612 if (strcmp(vl->plugin, vl->type) != 0) {
613 fields[fields_num] = vl->plugin;
614 fields_num++;
615 }
616 fields[fields_num] = vl->type;
617 fields_num++;
619 if (strcmp("value", ds->ds[ds_index].name) != 0) {
620 fields[fields_num] = ds->ds[ds_index].name;
621 fields_num++;
622 }
624 /* Prometheus best practices:
625 * cumulative metrics should have a "total" suffix. */
626 if ((ds->ds[ds_index].type == DS_TYPE_COUNTER) ||
627 (ds->ds[ds_index].type == DS_TYPE_DERIVE)) {
628 fields[fields_num] = "total";
629 fields_num++;
630 }
632 char name[5 * DATA_MAX_NAME_LEN];
633 strjoin(name, sizeof(name), (char **)fields, fields_num, "_");
634 return strdup(name);
635 }
637 /* metric_family_get looks up the matching metric family, allocating it if
638 * necessary. */
639 static Io__Prometheus__Client__MetricFamily *
640 metric_family_get(data_set_t const *ds, value_list_t const *vl, size_t ds_index,
641 _Bool allocate) {
642 char *name = metric_family_name(ds, vl, ds_index);
643 if (name == NULL) {
644 ERROR("write_prometheus plugin: Allocating metric family name failed.");
645 return NULL;
646 }
648 Io__Prometheus__Client__MetricFamily *fam = NULL;
649 if (c_avl_get(metrics, name, (void *)&fam) == 0) {
650 sfree(name);
651 assert(fam != NULL);
652 return fam;
653 }
655 if (!allocate)
656 return NULL;
658 fam = metric_family_create(name, ds, vl, ds_index);
659 if (fam == NULL) {
660 ERROR("write_prometheus plugin: Allocating metric family failed.");
661 sfree(name);
662 return NULL;
663 }
665 /* If successful, "name" is owned by "fam", i.e. don't free it here. */
666 DEBUG("write_prometheus plugin: metric family \"%s\" has been created.",
667 name);
668 name = NULL;
670 int status = c_avl_insert(metrics, fam->name, fam);
671 if (status != 0) {
672 ERROR("write_prometheus plugin: Adding \"%s\" failed.", name);
673 metric_family_destroy(fam);
674 return NULL;
675 }
677 return fam;
678 }
679 /* }}} */
681 /*
682 * collectd callbacks
683 */
684 static int prom_config(oconfig_item_t *ci) {
685 for (int i = 0; i < ci->children_num; i++) {
686 oconfig_item_t *child = ci->children + i;
688 if (strcasecmp("Port", child->key) == 0) {
689 int status = cf_util_get_port_number(child);
690 if (status > 0)
691 httpd_port = (unsigned short)status;
692 } else if (strcasecmp("StalenessDelta", child->key) == 0) {
693 cf_util_get_cdtime(child, &staleness_delta);
694 } else {
695 WARNING("write_prometheus plugin: Ignoring unknown configuration option "
696 "\"%s\".",
697 child->key);
698 }
699 }
701 return 0;
702 }
704 static int prom_init() {
705 if (metrics == NULL) {
706 metrics = c_avl_create((void *)strcmp);
707 if (metrics == NULL) {
708 ERROR("write_prometheus plugin: c_avl_create() failed.");
709 return -1;
710 }
711 }
713 if (httpd == NULL) {
714 unsigned int flags = MHD_USE_THREAD_PER_CONNECTION;
715 #if MHD_VERSION >= 0x00093300
716 flags |= MHD_USE_DUAL_STACK;
717 #endif
719 httpd = MHD_start_daemon(flags, httpd_port,
720 /* MHD_AcceptPolicyCallback = */ NULL,
721 /* MHD_AcceptPolicyCallback arg = */ NULL,
722 http_handler, NULL, MHD_OPTION_END);
723 if (httpd == NULL) {
724 ERROR("write_prometheus plugin: MHD_start_daemon() failed.");
725 return -1;
726 }
727 DEBUG("write_prometheus plugin: Successfully started microhttpd %s",
728 MHD_get_version());
729 }
731 return 0;
732 }
734 static int prom_write(data_set_t const *ds, value_list_t const *vl,
735 __attribute__((unused)) user_data_t *ud) {
736 pthread_mutex_lock(&metrics_lock);
738 for (size_t i = 0; i < ds->ds_num; i++) {
739 Io__Prometheus__Client__MetricFamily *fam =
740 metric_family_get(ds, vl, i, /* allocate = */ 1);
741 if (fam == NULL)
742 continue;
744 int status = metric_family_update(fam, ds, vl, i);
745 if (status != 0) {
746 ERROR("write_prometheus plugin: Updating metric \"%s\" failed with "
747 "status %d",
748 fam->name, status);
749 continue;
750 }
751 }
753 pthread_mutex_unlock(&metrics_lock);
754 return 0;
755 }
757 static int prom_missing(value_list_t const *vl,
758 __attribute__((unused)) user_data_t *ud) {
759 data_set_t const *ds = plugin_get_ds(vl->type);
760 if (ds == NULL)
761 return ENOENT;
763 pthread_mutex_lock(&metrics_lock);
765 for (size_t i = 0; i < ds->ds_num; i++) {
766 Io__Prometheus__Client__MetricFamily *fam =
767 metric_family_get(ds, vl, i, /* allocate = */ 0);
768 if (fam == NULL)
769 continue;
771 int status = metric_family_delete_metric(fam, vl);
772 if (status != 0) {
773 ERROR("write_prometheus plugin: Deleting a metric in family \"%s\" "
774 "failed with status %d",
775 fam->name, status);
777 continue;
778 }
780 if (fam->n_metric == 0) {
781 int status = c_avl_remove(metrics, fam->name, NULL, NULL);
782 if (status != 0) {
783 ERROR("write_prometheus plugin: Deleting metric family \"%s\" failed "
784 "with status %d",
785 fam->name, status);
786 continue;
787 }
788 metric_family_destroy(fam);
789 }
790 }
792 pthread_mutex_unlock(&metrics_lock);
793 return 0;
794 }
796 static int prom_shutdown() {
797 if (httpd != NULL) {
798 MHD_stop_daemon(httpd);
799 httpd = NULL;
800 }
802 pthread_mutex_lock(&metrics_lock);
803 if (metrics != NULL) {
804 char *name;
805 Io__Prometheus__Client__MetricFamily *fam;
806 while (c_avl_pick(metrics, (void *)&name, (void *)&fam) == 0) {
807 assert(name == fam->name);
808 name = NULL;
810 metric_family_destroy(fam);
811 }
812 c_avl_destroy(metrics);
813 metrics = NULL;
814 }
815 pthread_mutex_unlock(&metrics_lock);
817 return 0;
818 }
820 void module_register() {
821 plugin_register_complex_config("write_prometheus", prom_config);
822 plugin_register_init("write_prometheus", prom_init);
823 plugin_register_write("write_prometheus", prom_write,
824 /* user data = */ NULL);
825 plugin_register_missing("write_prometheus", prom_missing,
826 /* user data = */ NULL);
827 plugin_register_shutdown("write_prometheus", prom_shutdown);
828 }
830 /* vim: set sw=2 sts=2 et fdm=marker : */