From eb2b34a45a79d98ff7cc36f4bff6b5b374546275 Mon Sep 17 00:00:00 2001
From: Philippe Richard <prichard@digitalocean.com>
Date: Tue, 10 Jan 2023 13:04:19 -0500
Subject: [PATCH] feat: enable cpu/memory process metrics (#293)

---
 cmd/do-agent/config.go        | 21 +++++++++++++++++++++
 cmd/do-agent/main.go          |  1 +
 internal/process/collector.go |  7 +++++++
 3 files changed, 29 insertions(+)

diff --git a/cmd/do-agent/config.go b/cmd/do-agent/config.go
index 339894d1..5ac9c2a9 100644
--- a/cmd/do-agent/config.go
+++ b/cmd/do-agent/config.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"hash/fnv"
 	"net/url"
 	"os"
 	"strings"
@@ -63,6 +64,8 @@ const (
 	defaultAuthURL          = internalProxyURL
 	defaultSonarURL         = ""
 	defaultWebListenAddress = "127.0.0.1:9100"
+
+	processScrapingDropletPct = 10
 )
 
 var defaultMetadataURL = fmt.Sprintf("%s/metadata", internalProxyURL)
@@ -165,6 +168,24 @@ func checkConfig() error {
 	return nil
 }
 
+func toggleGradualRollouts() {
+	hostname, err := os.Hostname()
+	if err != nil {
+		return
+	}
+
+	hash := fnv.New64a()
+	_, err = hash.Write([]byte(hostname))
+	if err != nil {
+		return
+	}
+
+	if hash.Sum64()%100 <= processScrapingDropletPct {
+		log.Debug("Enabling process scraping")
+		config.noProcesses = false
+	}
+}
+
 func initWriter(wc *prometheus.CounterVec) (metricWriter, limiter) {
 	if config.stdoutOnly {
 		return writer.NewFile(os.Stdout, wc), &constThrottler{wait: 10 * time.Second}
diff --git a/cmd/do-agent/main.go b/cmd/do-agent/main.go
index b9d73e51..01e27520 100644
--- a/cmd/do-agent/main.go
+++ b/cmd/do-agent/main.go
@@ -26,6 +26,7 @@ func main() {
 		log.Fatal("configuration failure: %+v", err)
 	}
 
+	toggleGradualRollouts()
 	cols := initCollectors()
 	reg := prometheus.NewRegistry()
 	reg.MustRegister(cols...)
diff --git a/internal/process/collector.go b/internal/process/collector.go
index b270d30c..070f6506 100644
--- a/internal/process/collector.go
+++ b/internal/process/collector.go
@@ -11,6 +11,7 @@ import (
 type processCollector struct {
 	collectFn func(chan<- prometheus.Metric)
 	rss       *prometheus.Desc
+	cpuTime   *prometheus.Desc
 }
 
 // NewProcessCollector returns a collector which exports the current state of
@@ -23,6 +24,11 @@ func NewProcessCollector() prometheus.Collector {
 			"Resident memory size in bytes.",
 			[]string{"process", "pid"}, nil,
 		),
+		cpuTime: prometheus.NewDesc(
+			"sonar_process_cpu_time_seconds",
+			"CPU time in seconds.",
+			[]string{"process", "pid"}, nil,
+		),
 	}
 
 	if _, err := procfs.NewStat(); err == nil {
@@ -66,5 +72,6 @@ func (c *processCollector) processCollect(ch chan<- prometheus.Metric) {
 		pid := strconv.Itoa(stat.PID)
 
 		ch <- prometheus.MustNewConstMetric(c.rss, prometheus.GaugeValue, float64(stat.ResidentMemory()), name, pid)
+		ch <- prometheus.MustNewConstMetric(c.cpuTime, prometheus.GaugeValue, stat.CPUTime(), name, pid)
 	}
 }