From 22c5e624bc6575ea24e04786e41218f55ab250a3 Mon Sep 17 00:00:00 2001
From: Alexander Voitov <sanya0996@gmail.com>
Date: Mon, 1 Jul 2019 21:51:30 +0300
Subject: [PATCH] export application metrics via /metrics

---
 collector/prometheus_collector.go | 10 ++++++++++
 info/v1/metric.go                 |  3 ++-
 metrics/prometheus.go             | 31 +++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/collector/prometheus_collector.go b/collector/prometheus_collector.go
index efc3f3f8..baad487b 100644
--- a/collector/prometheus_collector.go
+++ b/collector/prometheus_collector.go
@@ -184,6 +184,14 @@ func (s byName) Less(i, j int) bool {
 	return s.prometheusLabels[i].GetName() < s.prometheusLabels[j].GetName()
 }
 
+func prometheusLabelSetToCadvisorLabels(promLabels model.Metric) map[string]string {
+	labels := make(map[string]string)
+	for k, v := range promLabels {
+		labels[string(k)] = string(v)
+	}
+	return labels
+}
+
 func prometheusLabelSetToCadvisorLabel(promLabels model.Metric) string {
 	labels := labelSetToLabelPairs(promLabels)
 	sort.Sort(byName{labels})
@@ -247,11 +255,13 @@ func (collector *PrometheusCollector) Collect(metrics map[string][]v1.MetricVal)
 			// TODO Handle multiple labels nicer. Prometheus metrics can have multiple
 			// labels, cadvisor only accepts a single string for the metric label.
 			label := prometheusLabelSetToCadvisorLabel(sample.Metric)
+			labels := prometheusLabelSetToCadvisorLabels(sample.Metric)
 
 			metric := v1.MetricVal{
 				FloatValue: float64(sample.Value),
 				Timestamp:  sample.Timestamp.Time(),
 				Label:      label,
+				Labels:     labels,
 			}
 			newMetrics[metName] = append(newMetrics[metName], metric)
 			if len(newMetrics) > collector.metricCountLimit {
diff --git a/info/v1/metric.go b/info/v1/metric.go
index 30c23ed1..39d1ac22 100644
--- a/info/v1/metric.go
+++ b/info/v1/metric.go
@@ -68,7 +68,8 @@ type MetricValBasic struct {
 // An exported metric.
 type MetricVal struct {
 	// Label associated with a metric
-	Label string `json:"label,omitempty"`
+	Label  string            `json:"label,omitempty"`
+	Labels map[string]string `json:"labels,omitempty"`
 
 	// Time at which the metric was queried
 	Timestamp time.Time `json:"timestamp"`
diff --git a/metrics/prometheus.go b/metrics/prometheus.go
index 2cdb08ab..9b2fbb7f 100644
--- a/metrics/prometheus.go
+++ b/metrics/prometheus.go
@@ -17,6 +17,7 @@ package metrics
 import (
 	"fmt"
 	"regexp"
+	"strings"
 	"time"
 
 	"github.com/google/cadvisor/container"
@@ -1675,6 +1676,36 @@ func (c *PrometheusCollector) collectContainersInfo(ch chan<- prometheus.Metric)
 			}
 		}
 	}
+
+	if c.includedMetrics.Has(container.AppMetrics) {
+		for _, container := range containers {
+			cstats := container.Stats
+			if len(cstats) > 0 {
+				last := cstats[len(cstats)-1]
+				for metricLabel, v := range last.CustomMetrics {
+					for _, metric := range v {
+						values := make([]string, 0, len(metric.Labels)+2)
+						labels := make([]string, 0, len(metric.Labels)+2)
+						labels = append(labels, "container_name")
+						values = append(values, container.ContainerReference.Name)
+						alias := strings.Join(container.ContainerReference.Aliases, ".")
+						labels = append(labels, "container_alias")
+						values = append(values, alias)
+						for label, value := range metric.Labels {
+							if label == "__name__" {
+								continue
+							}
+							labels = append(labels, sanitizeLabelName(label))
+							values = append(values, value)
+						}
+						desc := prometheus.NewDesc(metricLabel, "Custom application metric.", labels, nil)
+						ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(metric.FloatValue), values...)
+					}
+				}
+
+			}
+		}
+	}
 }
 
 func (c *PrometheusCollector) collectVersionInfo(ch chan<- prometheus.Metric) {