From 524a1f0712636a1afcbc639532b66d50ffe2d309 Mon Sep 17 00:00:00 2001
From: Diptanu Choudhury <diptanuc@gmail.com>
Date: Mon, 30 Oct 2017 12:19:11 -0700
Subject: [PATCH] Publishing metrics for job summary

---
 command/agent/agent.go |  3 +++
 nomad/config.go        |  4 ++++
 nomad/leader.go        | 49 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/command/agent/agent.go b/command/agent/agent.go
index 0c8072629..e47e8be3e 100644
--- a/command/agent/agent.go
+++ b/command/agent/agent.go
@@ -233,6 +233,9 @@ func convertServerConfig(agentConfig *Config, logOutput io.Writer) (*nomad.Confi
 	// Set the TLS config
 	conf.TLSConfig = agentConfig.TLSConfig
 
+	// Setup telemetry related config
+	conf.StatsCollectionInterval = agentConfig.Telemetry.collectionInterval
+
 	return conf, nil
 }
 
diff --git a/nomad/config.go b/nomad/config.go
index db4939106..fecac1dfa 100644
--- a/nomad/config.go
+++ b/nomad/config.go
@@ -245,6 +245,10 @@ type Config struct {
 
 	// SentinelConfig is this Agent's Sentinel configuration
 	SentinelConfig *config.SentinelConfig
+
+	// StatsCollectionInterval is the interval at which the Nomad server
+	// publishes metrics which are periodic in nature like updating gauges
+	StatsCollectionInterval time.Duration
 }
 
 // CheckVersion is used to check if the ProtocolVersion is valid
diff --git a/nomad/leader.go b/nomad/leader.go
index 8a4d2dbab..97b52c2de 100644
--- a/nomad/leader.go
+++ b/nomad/leader.go
@@ -180,6 +180,9 @@ func (s *Server) establishLeadership(stopCh chan struct{}) error {
 	// Periodically unblock failed allocations
 	go s.periodicUnblockFailedEvals(stopCh)
 
+	// Periodically publish job summary metrics
+	go s.publishJobSummaryMetrics(stopCh)
+
 	// Setup the heartbeat timers. This is done both when starting up or when
 	// a leader fail over happens. Since the timers are maintained by the leader
 	// node, effectively this means all the timers are renewed at the time of failover.
@@ -519,6 +522,52 @@ func (s *Server) periodicUnblockFailedEvals(stopCh chan struct{}) {
 	}
 }
 
+// publishJobSummaryMetrics publishes the job summaries as metrics
+func (s *Server) publishJobSummaryMetrics(stopCh chan struct{}) {
+	// Using a timer instead of a ticker so that we can publish after the
+	// current batch of metrics have been published
+	timer := time.NewTimer(0)
+	defer timer.Stop()
+
+	for {
+		select {
+		case <-stopCh:
+			return
+		case <-timer.C:
+			state, err := s.State().Snapshot()
+			if err != nil {
+				timer.Reset(s.config.StatsCollectionInterval)
+				s.logger.Printf("[ERR] nomad: failed to get state: %v", err)
+				continue
+			}
+			ws := memdb.NewWatchSet()
+			iter, err := state.JobSummaries(ws)
+			if err != nil {
+				timer.Reset(s.config.StatsCollectionInterval)
+				s.logger.Printf("[ERR] nomad: failed to get job summaries: %v", err)
+				continue
+			}
+
+			for {
+				raw := iter.Next()
+				if raw == nil {
+					break
+				}
+				summary := raw.(*structs.JobSummary)
+				for name, tgSummary := range summary.Summary {
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "queued"}, float32(tgSummary.Queued))
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "complete"}, float32(tgSummary.Complete))
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "failed"}, float32(tgSummary.Failed))
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "running"}, float32(tgSummary.Running))
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "starting"}, float32(tgSummary.Starting))
+					metrics.SetGauge([]string{"nomad", "job_summary", summary.JobID, name, "lost"}, float32(tgSummary.Lost))
+				}
+			}
+			timer.Reset(s.config.StatsCollectionInterval)
+		}
+	}
+}
+
 // revokeLeadership is invoked once we step down as leader.
 // This is used to cleanup any state that may be specific to a leader.
 func (s *Server) revokeLeadership() error {