MEDIUM: contrib/prometheus-exporter: Use dynamic labels instead of static ones

Instead of using static labels for metrics, we now use an array of labels,
filled for each metrics if necessary and passed to the dump function. This
way, it is easier to extend the promex service. For now, there are at most 8
labels per metrics. This limit may be raised by changing PROMEX_MAX_LABELS
value. And to ease labels addition, a label is defined as a key/value
pair. The formatting is handled by the dump function.

For the proxies and servers, the first entry of the array is always the
proxy name. In addition, for the servers, the second entry is always the
server name.

diff --git a/contrib/prometheus-exporter/service-prometheus.c b/contrib/prometheus-exporter/service-prometheus.c
index 43eb2f15289ff73bc5dbd68ee6cda4fcdaf2178a..dbf4c7f396f5a139bb79cc5c30282dc41e8ef2d7 100644 (file)
--- a/contrib/prometheus-exporter/service-prometheus.c
+++ b/contrib/prometheus-exporter/service-prometheus.c
@@ -91,9 +91,8 @@ enum promex_mt_type {
  */
 #define PROMEX_MAX_METRIC_LENGTH 512
 
-/* Some labels for build_info */
-#define PROMEX_VERSION_LABEL "version=\"" HAPROXY_VERSION "\""
-#define PROMEX_BUILDINFO_LABEL PROMEX_VERSION_LABEL
+/* The max number of labels per metric */
+#define PROMEX_MAX_LABELS 8
 
 /* Describe a prometheus metric */
 struct promex_metric {
@@ -102,6 +101,12 @@ struct promex_metric {
        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
@@ -379,19 +384,14 @@ const struct ist promex_st_metric_desc[ST_F_TOTAL_FIELDS] = {
        [ST_F_NEED_CONN_EST]  = IST("Estimated needed number of connections."),
 };
 
-/* Specific labels for all info fields. Empty by default. */
-const struct ist promex_inf_metric_labels[INF_TOTAL_FIELDS] = {
-       [INF_BUILD_INFO]  = IST(PROMEX_BUILDINFO_LABEL),
-};
-
-/* Specific labels for all stats fields. Empty by default. */
-const struct ist promex_st_metric_labels[ST_F_TOTAL_FIELDS] = {
-       [ST_F_HRSP_1XX]   = IST("code=\"1xx\""),
-       [ST_F_HRSP_2XX]   = IST("code=\"2xx\""),
-       [ST_F_HRSP_3XX]   = IST("code=\"3xx\""),
-       [ST_F_HRSP_4XX]   = IST("code=\"4xx\""),
-       [ST_F_HRSP_5XX]   = IST("code=\"5xx\""),
-       [ST_F_HRSP_OTHER] = IST("code=\"other\""),
+/* Specific labels for all ST_F_HRSP_* fields */
+const struct ist promex_hrsp_code[1 + ST_F_HRSP_OTHER - ST_F_HRSP_1XX] = {
+       [ST_F_HRSP_1XX - ST_F_HRSP_1XX]   = IST("1xx"),
+       [ST_F_HRSP_2XX - ST_F_HRSP_1XX]   = IST("2xx"),
+       [ST_F_HRSP_3XX - ST_F_HRSP_1XX]   = IST("3xx"),
+       [ST_F_HRSP_4XX - ST_F_HRSP_1XX]   = IST("4xx"),
+       [ST_F_HRSP_5XX - ST_F_HRSP_1XX]   = IST("5xx"),
+       [ST_F_HRSP_OTHER - ST_F_HRSP_1XX] = IST("other"),
 };
 
 enum promex_front_state {
@@ -531,7 +531,7 @@ static int promex_dump_metric_header(struct appctx *appctx, struct htx *htx,
  */
 static int promex_dump_metric(struct appctx *appctx, struct htx *htx, struct ist prefix,
                              const  struct promex_metric *metric, struct field *val,
-                             struct ist metric_label, struct ist *out, size_t max)
+                             struct promex_label *labels, struct ist *out, size_t max)
 {
        struct ist name = { .ptr = (char[PROMEX_MAX_NAME_LEN]){ 0 }, .len = 0 };
        size_t len = out->len;
@@ -548,36 +548,35 @@ static int promex_dump_metric(struct appctx *appctx, struct htx *htx, struct ist
            !promex_dump_metric_header(appctx, htx, metric, name, out, max))
                goto full;
 
-       if (appctx->ctx.stats.flags & PROMEX_FL_INFO_METRIC) {
-               const struct ist label = promex_inf_metric_labels[appctx->st2];
+       if (istcat(out, name, max) == -1)
+               goto full;
 
-               if (istcat(out, name, max) == -1 ||
-                   (label.len && istcat(out, ist("{"), max) == -1) ||
-                   (label.len && istcat(out, label, max) == -1) ||
-                   (label.len && istcat(out, ist("}"), max) == -1) ||
-                   istcat(out, ist(" "), max) == -1)
+       if (isttest(labels[0].name)) {
+               int i;
+
+               if (istcat(out, ist("{"), max) == -1)
                        goto full;
-       }
-       else {
-               struct proxy *px = appctx->ctx.stats.obj1;
-               struct server *srv = appctx->ctx.stats.obj2;
-               const struct ist label = promex_st_metric_labels[appctx->st2];
-
-               if (istcat(out, name, max) == -1 ||
-                   istcat(out, ist("{proxy=\""), max) == -1 ||
-                   istcat(out, ist2(px->id, strlen(px->id)), max) == -1 ||
-                   istcat(out, ist("\""), max) == -1 ||
-                   (srv && istcat(out, ist(",server=\""), max) == -1) ||
-                   (srv && istcat(out, ist2(srv->id, strlen(srv->id)), max) == -1) ||
-                   (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)
+
+               for (i = 0; isttest(labels[i].name); i++) {
+                       if (!isttest(labels[i].value))
+                               continue;
+
+                       if ((i && istcat(out, ist(","), max) == -1) ||
+                           istcat(out, labels[i].name, max) == -1 ||
+                           istcat(out, ist("=\""), max) == -1 ||
+                           istcat(out, labels[i].value, max) == -1 ||
+                           istcat(out, ist("\""), max) == -1)
+                               goto full;
+               }
+
+               if (istcat(out, ist("}"), max) == -1)
                        goto full;
+
        }
 
+       if (istcat(out, ist(" "), max) == -1)
+               goto full;
+
        trash.data = out->len;
        if (!promex_metric_to_str(&trash, val, max))
                goto full;
@@ -608,11 +607,15 @@ static int promex_dump_global_metrics(struct appctx *appctx, struct htx *htx)
                return -1;
 
        for (; appctx->st2 < INF_TOTAL_FIELDS; appctx->st2++) {
+               struct promex_label labels[PROMEX_MAX_LABELS-1] = {};
+
                if (!(promex_global_metrics[appctx->st2].flags & appctx->ctx.stats.flags))
                        continue;
 
                switch (appctx->st2) {
                        case INF_BUILD_INFO:
+                               labels[0].name  = ist("version");
+                               labels[0].value = ist(HAPROXY_VERSION);
                                val = mkf_u32(FN_GAUGE, 1);
                                break;
 
@@ -621,7 +624,7 @@ static int promex_dump_global_metrics(struct appctx *appctx, struct htx *htx)
                }
 
                if (!promex_dump_metric(appctx, htx, prefix, &promex_global_metrics[appctx->st2],
-                                       &val, IST_NULL, &out, max))
+                                       &val, labels, &out, max))
                        goto full;
 
                appctx->ctx.stats.flags |= PROMEX_FL_METRIC_HDR;
@@ -639,19 +642,6 @@ 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)
@@ -665,7 +655,6 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *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++) {
@@ -673,8 +662,13 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
                        continue;
 
                while (appctx->ctx.stats.obj1) {
+                       struct promex_label labels[PROMEX_MAX_LABELS-1] = {};
+
                        px = appctx->ctx.stats.obj1;
 
+                       labels[0].name  = ist("proxy");
+                       labels[0].value = ist2(px->id, strlen(px->id));
+
                        /* skip the disabled proxies, global frontend and non-networked ones */
                        if (px->disabled || px->uuid <= 0 || !(px->cap & PR_CAP_FE))
                                goto next_px;
@@ -686,11 +680,11 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
                                case ST_F_STATUS:
                                        state = !px->disabled;
                                        for (i = 0; i < PROMEX_FRONT_STATE_COUNT; i++) {
+                                               labels[1].name = ist("state");
+                                               labels[1].value = promex_front_st[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))
+                                                                       &val, labels, &out, max))
                                                        goto full;
                                        }
                                        goto next_px;
@@ -715,8 +709,10 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
                                case ST_F_HRSP_OTHER:
                                        if (px->mode != PR_MODE_HTTP)
                                                goto next_px;
-                                       val = stats[appctx->st2];
                                        appctx->ctx.stats.flags &= ~PROMEX_FL_METRIC_HDR;
+                                       labels[1].name = ist("code");
+                                       labels[1].value = promex_hrsp_code[appctx->st2 - ST_F_HRSP_1XX];
+                                       val = stats[appctx->st2];
                                        break;
 
                                default:
@@ -724,7 +720,7 @@ static int promex_dump_front_metrics(struct appctx *appctx, struct htx *htx)
                        }
 
                        if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
-                                               &val, IST_NULL, &out, max))
+                                               &val, labels, &out, max))
                                goto full;
                  next_px:
                        appctx->ctx.stats.obj1 = px->next;
@@ -759,7 +755,6 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
        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++) {
@@ -767,8 +762,13 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
                        continue;
 
                while (appctx->ctx.stats.obj1) {
+                       struct promex_label labels[PROMEX_MAX_LABELS-1] = {};
+
                        px = appctx->ctx.stats.obj1;
 
+                       labels[0].name  = ist("proxy");
+                       labels[0].value = ist2(px->id, strlen(px->id));
+
                        /* skip the disabled proxies, global frontend and non-networked ones */
                        if (px->disabled || px->uuid <= 0 || !(px->cap & PR_CAP_BE))
                                goto next_px;
@@ -780,11 +780,11 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
                                case ST_F_STATUS:
                                        state = ((px->lbprm.tot_weight > 0 || !px->srv) ? 1 : 0);
                                        for (i = 0; i < PROMEX_BACK_STATE_COUNT; i++) {
+                                               labels[1].name = ist("state");
+                                               labels[1].value = promex_back_st[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))
+                                                                       &val, labels, &out, max))
                                                        goto full;
                                        }
                                        goto next_px;
@@ -840,6 +840,8 @@ static int promex_dump_back_metrics(struct appctx *appctx, struct htx *htx)
                                        if (px->mode != PR_MODE_HTTP)
                                                goto next_px;
                                        appctx->ctx.stats.flags &= ~PROMEX_FL_METRIC_HDR;
+                                       labels[1].name = ist("code");
+                                       labels[1].value = promex_hrsp_code[appctx->st2 - ST_F_HRSP_1XX];
                                        val = stats[appctx->st2];
                                        break;
 
@@ -848,7 +850,7 @@ 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, IST_NULL, &out, max))
+                                               &val, labels, &out, max))
                                goto full;
                  next_px:
                        appctx->ctx.stats.obj1 = px->next;
@@ -884,7 +886,6 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
        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++) {
@@ -892,8 +893,13 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                        continue;
 
                while (appctx->ctx.stats.obj1) {
+                       struct promex_label labels[PROMEX_MAX_LABELS-1] = {};
+
                        px = appctx->ctx.stats.obj1;
 
+                       labels[0].name  = ist("proxy");
+                       labels[0].value = ist2(px->id, strlen(px->id));
+
                        /* skip the disabled proxies, global frontend and non-networked ones */
                        if (px->disabled || px->uuid <= 0 || !(px->cap & PR_CAP_BE))
                                goto next_px;
@@ -901,6 +907,9 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                        while (appctx->ctx.stats.obj2) {
                                sv = appctx->ctx.stats.obj2;
 
+                               labels[1].name  = ist("server");
+                               labels[1].value = ist2(sv->id, strlen(sv->id));
+
                                if (!stats_fill_sv_stats(px, sv, 0, stats, ST_F_TOTAL_FIELDS, &(appctx->st2)))
                                        return -1;
 
@@ -912,10 +921,10 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                                                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;
+                                                       labels[2].name = ist("state");
+                                                       labels[2].value = promex_srv_st[i];
                                                        if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
-                                                                               &val, metric_label, &out, max))
+                                                                               &val, labels, &out, max))
                                                                goto full;
                                                }
                                                goto next_sv;
@@ -981,6 +990,8 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                                                if (px->mode != PR_MODE_HTTP)
                                                        goto next_px;
                                                appctx->ctx.stats.flags &= ~PROMEX_FL_METRIC_HDR;
+                                               labels[2].name = ist("code");
+                                               labels[2].value = promex_hrsp_code[appctx->st2 - ST_F_HRSP_1XX];
                                                val = stats[appctx->st2];
                                                break;
 
@@ -989,7 +1000,7 @@ static int promex_dump_srv_metrics(struct appctx *appctx, struct htx *htx)
                                }
 
                                if (!promex_dump_metric(appctx, htx, prefix, &promex_st_metrics[appctx->st2],
-                                                       &val, IST_NULL, &out, max))
+                                                       &val, labels, &out, max))
                                        goto full;
                          next_sv:
                                appctx->ctx.stats.obj2 = sv->next;