MAJOR: contrib/prometheus-exporter: move ftd/bkd/srv states to labels

this patch is a breaking change between v2.3 and v2.4: we move from
using gauge value for frontend/backend/servers states to labels values.

the main motivation being I realised it is very difficult to make use of
it without hard coded quirks on prometheus client side; especially
because the main use is often to group by state, which is harder when
the state is the value of the metric.

in order to achieve that we iterate on the status metric to generate
labels, and so as many metrics.

this is the first step to resolve github issue #1029
A second step should address health check states.

Signed-off-by: William Dauchy <wdauchy@gmail.com>

diff --git a/contrib/prometheus-exporter/service-prometheus.c b/contrib/prometheus-exporter/service-prometheus.c
index dac301fdd4d3cb3233491cc578a611e53a2fe521..43eb2f15289ff73bc5dbd68ee6cda4fcdaf2178a 100644 (file)
--- a/contrib/prometheus-exporter/service-prometheus.c
+++ b/contrib/prometheus-exporter/service-prometheus.c
@@ -295,7 +295,7 @@ const struct ist promex_st_metric_desc[ST_F_TOTAL_FIELDS] = {
        [ST_F_ERESP]          = IST("Total number of response errors."),
        [ST_F_WRETR]          = IST("Total number of retry warnings."),
        [ST_F_WREDIS]         = IST("Total number of redispatch warnings."),
-       [ST_F_STATUS]         = IST("Current status of the service (frontend: 0=STOP, 1=UP - backend: 0=DOWN, 1=UP - server: 0=DOWN, 1=UP, 2=MAINT, 3=DRAIN, 4=NOLB)."),
+       [ST_F_STATUS]         = IST("Current status of the service."),
        [ST_F_WEIGHT]         = IST("Service weight."),
        [ST_F_ACT]            = IST("Current number of active servers."),
        [ST_F_BCK]            = IST("Current number of backup servers."),
@@ -530,8 +530,8 @@ static int promex_dump_metric_header(struct appctx *appctx, struct htx *htx,
  * success. Otherwise if <out> length exceeds <max>, it returns 0.
  */
 static int promex_dump_metric(struct appctx *appctx, struct htx *htx, struct ist prefix,
-                            const  struct promex_metric *metric, struct field *val,
-                             struct ist *out, size_t max)
+                             const  struct promex_metric *metric, struct field *val,
+                             struct ist metric_label, struct ist *out, size_t max)
 {
        struct ist name = { .ptr = (char[PROMEX_MAX_NAME_LEN]){ 0 }, .len = 0 };
        size_t len = out->len;
@@ -572,6 +572,8 @@ static int promex_dump_metric(struct appctx *appctx, struct htx *htx, struct ist
                    (srv && istcat(out, ist("\""), max) == -1) ||
                    (label.len && istcat(out, ist(","), max) == -1) ||
                    (label.len && istcat(out, label, max) == -1) ||
+                   (metric_label.len && istcat(out, ist(","), max) == -1) ||
+                   (metric_label.len && istcat(out, metric_label, max) == -1) ||
                    istcat(out, ist("} "), max) == -1)
                        goto full;
        }
@@ -618,7 +620,8 @@ static int promex_dump_global_metrics(struct appctx *appctx, struct htx *htx)
                                val = info[appctx->st2];
                }
 
-               if (!promex_dump_metric(appctx, htx, prefix, &promex_global_metrics[appctx->st2], &val, &out, max))
+               if (!promex_dump_metric(appctx, htx, prefix, &promex_global_metrics[appctx->st2],
+                                       &val, IST_NULL, &out, max))
                        goto full;
 
                appctx->ctx.stats.flags |= PROMEX_FL_METRIC_HDR;
@@ -636,6 +639,19 @@ static int promex_dump_global_metrics(struct appctx *appctx, struct htx *htx)
        goto end;
 }
 
+/* Helper to generate state labels for ftd/bkd/srv */
+static int promex_state_label(struct ist *metric_label, struct ist state)
+{
+       struct buffer *state_label = get_trash_chunk();
+
+       *metric_label = ist2(state_label->area, 0);
+       if (istcat(metric_label, ist("state=\""), state_label->size) == -1 ||
+           istcat(metric_label, state, state_label->size) == -1 ||
+           istcat(metric_label, ist("\""), state_label->size) == -1)
+               return -1;
+       return 1;
+}
+
 /* Dump frontends metrics (prefixed by "haproxy_frontend_"). It returns 1 on success,
  * 0 if <htx> is full and -1 in case of any error. */
 static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
@@ -648,6 +664,9 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
        size_t max = htx_get_max_blksz(htx, channel_htx_recv_max(chn, htx));
        struct field *stats = stat_l[STATS_DOMAIN_PROXY];
        int ret = 1;
+       enum promex_front_state state;
+       struct ist metric_label;
+       int i;
 
        for (;appctx->st2 < ST_F_TOTAL_FIELDS; appctx->st2++) {
                if (!(promex_st_metrics[appctx->st2].flags & appctx->ctx.stats.flags))
@@ -665,8 +684,16 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
 
                        switch (appctx->st2) {
                                case ST_F_STATUS:
-                                       val = mkf_u32(FO_STATUS, !px->disabled);
-                                       break;
+                                       state = !px->disabled;
+                                       for (i = 0; i < PROMEX_FRONT_STATE_COUNT; i++) {
+                                               val = mkf_u32(FO_STATUS, state == i);
+                                               if (promex_state_label(&metric_label, promex_front_st[i]) == -1)
+                                                       goto full;
+                                               if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
+                                                                       &val, metric_label, &out, max))
+                                                       goto full;
+                                       }
+                                       goto next_px;
                                case ST_F_REQ_RATE_MAX:
                                case ST_F_REQ_TOT:
                                case ST_F_HRSP_1XX:
@@ -696,7 +723,8 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
                                        val = stats[appctx->st2];
                        }
 
-                       if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2], &val, &out, max))
+                       if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
+                                               &val, IST_NULL, &out, max))
                                goto full;
                  next_px:
                        appctx->ctx.stats.obj1 = px->next;
@@ -730,6 +758,9 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
        struct field *stats = stat_l[STATS_DOMAIN_PROXY];
        int ret = 1;
        double secs;
+       enum promex_back_state state;
+       struct ist metric_label;
+       int i;
 
        for (;appctx->st2 < ST_F_TOTAL_FIELDS; appctx->st2++) {
                if (!(promex_st_metrics[appctx->st2].flags & appctx->ctx.stats.flags))
@@ -747,8 +778,16 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
 
                        switch (appctx->st2) {
                                case ST_F_STATUS:
-                                       val = mkf_u32(FO_STATUS, (px->lbprm.tot_weight > 0 || !px->srv) ? 1 : 0);
-                                       break;
+                                       state = ((px->lbprm.tot_weight > 0 || !px->srv) ? 1 : 0);
+                                       for (i = 0; i < PROMEX_BACK_STATE_COUNT; i++) {
+                                               val = mkf_u32(FO_STATUS, state == i);
+                                               if (promex_state_label(&metric_label, promex_back_st[i]) == -1)
+                                                       goto full;
+                                               if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
+                                                                       &val, metric_label, &out, max))
+                                                       goto full;
+                                       }
+                                       goto next_px;
                                case ST_F_QTIME:
                                        secs = (double)swrate_avg(px->be_counters.q_time, TIME_STATS_SAMPLES) / 1000.0;
                                        val = mkf_flt(FN_AVG, secs);
@@ -809,7 +848,7 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
                        }
 
                        if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
-                                               &val, &out, max))
+                                               &val, IST_NULL, &out, max))
                                goto full;
                  next_px:
                        appctx->ctx.stats.obj1 = px->next;
@@ -844,6 +883,9 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
        struct field *stats = stat_l[STATS_DOMAIN_PROXY];
        int ret = 1;
        double secs;
+       enum promex_srv_state state;
+       struct ist metric_label;
+       int i;
 
        for (;appctx->st2 < ST_F_TOTAL_FIELDS; appctx->st2++) {
                if (!(promex_st_metrics[appctx->st2].flags & appctx->ctx.stats.flags))
@@ -867,8 +909,16 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
 
                                switch (appctx->st2) {
                                        case ST_F_STATUS:
-                                               val = mkf_u32(FO_STATUS, promex_srv_status(sv));
-                                               break;
+                                               state = promex_srv_status(sv);
+                                               for (i = 0; i < PROMEX_SRV_STATE_COUNT; i++) {
+                                                       val = mkf_u32(FO_STATUS, state == i);
+                                                       if (promex_state_label(&metric_label, promex_srv_st[i]) == -1)
+                                                               goto full;
+                                                       if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
+                                                                               &val, metric_label, &out, max))
+                                                               goto full;
+                                               }
+                                               goto next_sv;
                                        case ST_F_QTIME:
                                                secs = (double)swrate_avg(sv->counters.q_time, TIME_STATS_SAMPLES) / 1000.0;
                                                val = mkf_flt(FN_AVG, secs);
@@ -938,7 +988,8 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                                                val = stats[appctx->st2];
                                }
 
-                               if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2], &val, &out, max))
+                               if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
+                                                       &val, IST_NULL, &out, max))
                                        goto full;
                          next_sv:
                                appctx->ctx.stats.obj2 = sv->next;