stats: Make exported metrics compliant with OpenMetrics standards

Commit based on github PR: https://github.com/dovecot/core/pull/136

Fix issues raised by promtool and prometheus client library parser.
Cleanup and code fixes by Siavash Tavakoli.

diff --git a/src/stats/stats-service-openmetrics.c b/src/stats/stats-service-openmetrics.c
index 6b312eb4ae321ca823fd806bb490f42662e867e9..f64abf7a81337bcc2d451bfca8634b51d9c561c0 100644 (file)
--- a/src/stats/stats-service-openmetrics.c
+++ b/src/stats/stats-service-openmetrics.c
@@ -14,7 +14,7 @@
 #include "stats-metrics.h"
 #include "stats-service-private.h"
 
-#define OPENMETRICS_CONTENT_VERSION "0.0.4"
+#define OPENMETRICS_CONTENT_VERSION "0.0.1"
 
 #ifdef DOVECOT_REVISION
 #define OPENMETRICS_BUILD_INFO \
@@ -94,35 +94,39 @@ static bool openmetrics_check_name(const char *name)
        return TRUE;
 }
 
-static void openmetrics_export_dovecot(string_t *out, int64_t timestamp)
+static void openmetrics_export_dovecot(string_t *out)
 {
        i_assert(stats_startup_time <= ioloop_time);
-       str_append(out, "# HELP dovecot_stats_uptime_seconds "
-                       "Dovecot stats service uptime\n");
-       str_append(out, "# TYPE dovecot_stats_uptime_seconds counter\n");
-       str_printfa(out, "dovecot_stats_uptime_seconds %"PRId64" %"PRId64"\n\n",
-                   (int64_t)(ioloop_time - stats_startup_time), timestamp);
+       str_append(out, "# HELP process_start_time_seconds "
+                       "Timestamp of service start\n");
+       str_append(out, "# TYPE process_start_time_seconds gauge\n");
+       str_printfa(out, "process_start_time_seconds %"PRIu64"\n",
+                   stats_startup_time);
 
-       str_append(out, "# HELP dovecot_build_info "
+       str_append(out, "# HELP dovecot_build "
                        "Dovecot build information\n");
-       str_append(out, "# TYPE dovecot_build_info untyped\n");
-       str_printfa(out, "dovecot_build_info{"OPENMETRICS_BUILD_INFO"} "
-                        "1 %"PRId64"\n", timestamp);
+       str_append(out, "# TYPE dovecot_build info\n");
+       str_append(out, "dovecot_build_info{"OPENMETRICS_BUILD_INFO"} 1\n");
+}
+
+static void openmetrics_export_eof(string_t *out)
+{
+       str_append(out, "# EOF\n");
 }
 
 static void
 openmetrics_export_metric_value(struct openmetrics_request *req, string_t *out,
-                               const struct metric *metric, int64_t timestamp)
+                               const struct metric *metric)
 {
        /* Metric name */
        str_append(out, "dovecot_");
        str_append(out, req->metric->name);
        switch (req->metric_type) {
        case OPENMETRICS_METRIC_TYPE_COUNT:
-               str_append(out, "_count");
+               str_append(out, "_total");
                break;
        case OPENMETRICS_METRIC_TYPE_DURATION:
-               str_append(out, "_duration_usecs_sum");
+               str_append(out, "_duration_seconds_total");
                break;
        case OPENMETRICS_METRIC_TYPE_HISTOGRAM:
                i_unreached();
@@ -136,14 +140,13 @@ openmetrics_export_metric_value(struct openmetrics_request *req, string_t *out,
        /* Value */
        switch (req->metric_type) {
        case OPENMETRICS_METRIC_TYPE_COUNT:
-               str_printfa(out, " %u %"PRId64"\n",
-                           stats_dist_get_count(metric->duration_stats),
-                           timestamp);
+               str_printfa(out, " %u\n",
+                           stats_dist_get_count(metric->duration_stats));
                break;
        case OPENMETRICS_METRIC_TYPE_DURATION:
-               str_printfa(out, " %"PRIu64" %"PRId64"\n",
-                           stats_dist_get_sum(metric->duration_stats),
-                           timestamp);
+               /* Convert from microseconds to seconds */
+               str_printfa(out, " %.6f\n",
+                           stats_dist_get_sum(metric->duration_stats)/1e6F);
                break;
        case OPENMETRICS_METRIC_TYPE_HISTOGRAM:
                i_unreached();
@@ -175,13 +178,12 @@ openmetrics_find_histogram_bucket(const struct metric *metric,
 static void
 openmetrics_export_histogram_bucket(struct openmetrics_request *req,
                                    string_t *out, const struct metric *metric,
-                                   intmax_t bucket_limit, int64_t count,
-                                   int64_t timestamp)
+                                   intmax_t bucket_limit, int64_t count)
 {
        /* Metric name */
        str_append(out, "dovecot_");
        str_append(out, metric->name);
-       str_append(out, "_histogram_bucket");
+       str_append(out, "_bucket");
        /* Labels */
        str_append_c(out, '{');
        if (str_len(req->labels) > 0) {
@@ -192,16 +194,16 @@ openmetrics_export_histogram_bucket(struct openmetrics_request *req,
                str_append(out, "le=\"+Inf\"");
        else
                str_printfa(out, "le=\"%jd\"", bucket_limit);
-       str_printfa(out, "} %"PRIu64" %"PRId64"\n", count, timestamp);
+       str_printfa(out, "} %"PRIu64"\n", count);
 }
 
 static void
 openmetrics_export_histogram(struct openmetrics_request *req, string_t *out,
-                            const struct metric *metric, int64_t timestamp)
+                            const struct metric *metric)
 {
        const struct stats_metric_settings_group_by *group_by =
                metric->group_by;
-       int64_t sum = 0;
+       float sum = 0;
        uint64_t count = 0;
 
        /* Buckets */
@@ -217,30 +219,31 @@ openmetrics_export_histogram(struct openmetrics_request *req, string_t *out,
 
                openmetrics_export_histogram_bucket(req, out, metric,
                                                    group_by->ranges[i].max,
-                                                   count, timestamp);
+                                                   count);
        }
        /* Sum */
        str_append(out, "dovecot_");
        str_append(out, metric->name);
-       str_append(out, "_histogram_sum");
+       str_append(out, "_sum");
        /* Labels */
        if (str_len(req->labels) > 0) {
                str_append_c(out, '{');
                str_append_str(out, req->labels);
                str_append_c(out, '}');
        }
-       str_printfa(out, " %"PRIu64" %"PRId64"\n", sum, timestamp);
+       /* Convert from microseconds to seconds */
+       str_printfa(out, " %.6f\n", sum/1e6F);
        /* Count */
        str_append(out, "dovecot_");
        str_append(out, metric->name);
-       str_append(out, "_histogram_count");
+       str_append(out, "_count");
        /* Labels */
        if (str_len(req->labels) > 0) {
                str_append_c(out, '{');
                str_append_str(out, req->labels);
                str_append_c(out, '}');
        }
-       str_printfa(out, " %"PRIu64" %"PRId64"\n", count, timestamp);
+       str_printfa(out, " %"PRIu64"\n", count);
 }
 
 static void
@@ -248,21 +251,18 @@ openmetrics_export_metric_header(struct openmetrics_request *req, string_t *out)
 {
        const struct metric *metric = req->metric;
 
-       /* Empty line */
-       str_append_c(out, '\n');
-
        /* Description */
        str_append(out, "# HELP dovecot_");
        str_append(out, metric->name);
        switch (req->metric_type) {
        case OPENMETRICS_METRIC_TYPE_COUNT:
-               str_append(out, "_count Total number");
+               str_append(out, " Total number of all events of this kind");
                break;
        case OPENMETRICS_METRIC_TYPE_DURATION:
-               str_append(out, "_duration_usecs_sum Duration");
+               str_append(out, "_duration_seconds Total duration of all events of this kind");
                break;
        case OPENMETRICS_METRIC_TYPE_HISTOGRAM:
-               str_append(out, "_histogram Histogram");
+               str_append(out, " Histogram");
                break;
        }
        if (*metric->set->description != '\0') {
@@ -275,20 +275,20 @@ openmetrics_export_metric_header(struct openmetrics_request *req, string_t *out)
        str_append(out, metric->name);
        switch (req->metric_type) {
        case OPENMETRICS_METRIC_TYPE_COUNT:
-               str_append(out, "_count counter\n");
+               str_append(out, " counter\n");
                break;
        case OPENMETRICS_METRIC_TYPE_DURATION:
-               str_append(out, "_duration_usecs_sum counter\n");
+               str_append(out, "_duration_seconds counter\n");
                break;
        case OPENMETRICS_METRIC_TYPE_HISTOGRAM:
-               str_append(out, "_histogram histogram\n");
+               str_append(out, " histogram\n");
                break;
        }
 }
 
 static void
 openmetrics_export_submetric(struct openmetrics_request *req, string_t *out,
-                            const struct metric *metric, int64_t timestamp)
+                            const struct metric *metric)
 {
        /* This metric may be a submetric and therefore have a label
           associated with it. */
@@ -303,11 +303,11 @@ openmetrics_export_submetric(struct openmetrics_request *req, string_t *out,
                    metric->group_by[0].func != STATS_METRIC_GROUPBY_QUANTIZED)
                        return;
 
-               openmetrics_export_histogram(req, out, metric, timestamp);
+               openmetrics_export_histogram(req, out, metric);
                return;
        }
 
-       openmetrics_export_metric_value(req, out, metric, timestamp);
+       openmetrics_export_metric_value(req, out, metric);
 
        req->has_submetric = TRUE;
 }
@@ -429,8 +429,7 @@ openmetrics_export_sub_metric_current(struct openmetrics_request *req)
 }
 
 static bool
-openmetrics_export_sub_metrics(struct openmetrics_request *req, string_t *out,
-                              int64_t timestamp)
+openmetrics_export_sub_metrics(struct openmetrics_request *req, string_t *out)
 {
        struct openmetrics_request_sub_metric *reqsm = NULL;
 
@@ -442,7 +441,7 @@ openmetrics_export_sub_metrics(struct openmetrics_request *req, string_t *out,
                /* No valid sub-metrics to export */
                return TRUE;
        }
-       openmetrics_export_submetric(req, out, reqsm->metric, timestamp);
+       openmetrics_export_submetric(req, out, reqsm->metric);
 
        /* Try do descend into sub-metrics tree for next sub-metric to export.
         */
@@ -463,10 +462,9 @@ openmetrics_export_sub_metrics(struct openmetrics_request *req, string_t *out,
 }
 
 static void
-openmetrics_export_metric_body(struct openmetrics_request *req, string_t *out,
-                              int64_t timestamp)
+openmetrics_export_metric_body(struct openmetrics_request *req, string_t *out)
 {
-       openmetrics_export_metric_value(req, out, req->metric, timestamp);
+       openmetrics_export_metric_value(req, out, req->metric);
 }
 
 static int
@@ -538,15 +536,14 @@ static void openmetrics_export_next(struct openmetrics_request *req)
 }
 
 static void
-openmetrics_export_continue(struct openmetrics_request *req, string_t *out,
-                           int64_t timestamp)
+openmetrics_export_continue(struct openmetrics_request *req, string_t *out)
 {
        switch (req->state) {
        case OPENMETRICS_REQUEST_STATE_INIT:
                /* Export the Dovecot base metrics. */
                i_assert(req->stats_iter == NULL);
                req->stats_iter = stats_metrics_iterate_init(stats_metrics);
-               openmetrics_export_dovecot(out, timestamp);
+               openmetrics_export_dovecot(out);
                req->state = OPENMETRICS_REQUEST_STATE_METRIC;
                break;
        case OPENMETRICS_REQUEST_STATE_METRIC:
@@ -583,7 +580,7 @@ openmetrics_export_continue(struct openmetrics_request *req, string_t *out,
                /* Export the sub-metrics for the current metric. This will
                   return for each sub-metric, so that the out string buffer
                   stays small. */
-               if (!openmetrics_export_sub_metrics(req, out, timestamp))
+               if (!openmetrics_export_sub_metrics(req, out))
                        break;
                /* All sub-metrics written. */
                if (req->metric_type == OPENMETRICS_METRIC_TYPE_HISTOGRAM ||
@@ -604,7 +601,7 @@ openmetrics_export_continue(struct openmetrics_request *req, string_t *out,
        case OPENMETRICS_REQUEST_STATE_METRIC_BODY:
                /* Export the body of the current metric. */
                str_truncate(req->labels, req->labels_pos);
-               openmetrics_export_metric_body(req, out, timestamp);
+               openmetrics_export_metric_body(req, out);
                openmetrics_export_next(req);
                break;
        case OPENMETRICS_REQUEST_STATE_FINISHED:
@@ -629,7 +626,6 @@ static void openmetrics_request_deinit(struct openmetrics_request *req)
 
 static int openmetrics_export(struct openmetrics_request *req)
 {
-       int64_t timestamp;
        string_t *out;
        int ret;
 
@@ -650,11 +646,6 @@ static int openmetrics_export(struct openmetrics_request *req)
                return 1;
        }
 
-       /* Record timestamp for metrics export */
-       i_assert(ioloop_timeval.tv_usec < 1000000);
-       timestamp = ((int64_t)ioloop_timeval.tv_sec * 1000 +
-                    (int64_t)ioloop_timeval.tv_usec / 1000);
-
        /* Export metrics into a string buffer and write that buffer to the
           output stream after each (sub-)metric, so that the string buffer
           stays small. The output stream buffer can grow bigger, but writing is
@@ -664,7 +655,7 @@ static int openmetrics_export(struct openmetrics_request *req)
        for (;;) {
                str_truncate(out, 0);
 
-               openmetrics_export_continue(req, out, timestamp);
+               openmetrics_export_continue(req, out);
 
                ret = openmetrics_send_buffer(req, out);
                if (ret < 0) {
@@ -683,6 +674,15 @@ static int openmetrics_export(struct openmetrics_request *req)
                }
        }
 
+       /* Send EOF */
+       str_truncate(out, 0);
+       openmetrics_export_eof(out);
+        ret = openmetrics_send_buffer(req, out);
+        if (ret < 0) {
+            openmetrics_handle_write_error(req);
+            return -1;
+        }
+
        /* Cleanup everything except the output stream */
        openmetrics_request_deinit(req);
 
@@ -735,7 +735,7 @@ stats_service_openmetrics_request(void *context ATTR_UNUSED,
        hsresp = http_server_response_create(hsreq, 200, "OK");
        http_server_response_add_header(
                hsresp, "Content-Type",
-               "text/plain; version="OPENMETRICS_CONTENT_VERSION"; "
+               "application/openmetrics-text; version="OPENMETRICS_CONTENT_VERSION"; "
                "charset=utf-8");
 
        req->output = http_server_response_get_payload_output(