From 9b97f44a704c9c31e45c864c105643e6b197abad Mon Sep 17 00:00:00 2001
From: xginn8 <xginn8@users.noreply.github.com>
Date: Mon, 16 Jul 2018 10:01:42 -0400
Subject: [PATCH] Add a counter for refused socket unit connections, available
 as of systemd 239 (#995)

Signed-off-by: xginn8 <mamcgi@gmail.com>
---
 CHANGELOG.md               |  1 +
 collector/systemd_linux.go | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f741f9f..85a04851 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 **Breaking changes**
 
 * [CHANGE]
+* [FEATURE] Collect NRefused property for systemd socket units (available as of systemd v239)
 * [FEATURE] Collect NRestarts property for systemd service units
 * [FEATURE] Add socket unit stats to systemd collector #968
 * [ENHANCEMENT]
diff --git a/collector/systemd_linux.go b/collector/systemd_linux.go
index 13dc0aa3..3e16c451 100644
--- a/collector/systemd_linux.go
+++ b/collector/systemd_linux.go
@@ -40,6 +40,7 @@ type systemdCollector struct {
 	timerLastTriggerDesc          *prometheus.Desc
 	socketAcceptedConnectionsDesc *prometheus.Desc
 	socketCurrentConnectionsDesc  *prometheus.Desc
+	socketRefusedConnectionsDesc  *prometheus.Desc
 	unitWhitelistPattern          *regexp.Regexp
 	unitBlacklistPattern          *regexp.Regexp
 }
@@ -78,6 +79,9 @@ func NewSystemdCollector() (Collector, error) {
 	socketCurrentConnectionsDesc := prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, subsystem, "socket_current_connections"),
 		"Current number of socket connections", []string{"name"}, nil)
+	socketRefusedConnectionsDesc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, subsystem, "socket_refused_connections_total"),
+		"Total number of refused socket connections", []string{"name"}, nil)
 	unitWhitelistPattern := regexp.MustCompile(fmt.Sprintf("^(?:%s)$", *unitWhitelist))
 	unitBlacklistPattern := regexp.MustCompile(fmt.Sprintf("^(?:%s)$", *unitBlacklist))
 
@@ -89,6 +93,7 @@ func NewSystemdCollector() (Collector, error) {
 		timerLastTriggerDesc:          timerLastTriggerDesc,
 		socketAcceptedConnectionsDesc: socketAcceptedConnectionsDesc,
 		socketCurrentConnectionsDesc:  socketCurrentConnectionsDesc,
+		socketRefusedConnectionsDesc:  socketRefusedConnectionsDesc,
 		unitWhitelistPattern:          unitWhitelistPattern,
 		unitBlacklistPattern:          unitBlacklistPattern,
 	}, nil
@@ -148,6 +153,9 @@ func (c *systemdCollector) collectSockets(ch chan<- prometheus.Metric, units []u
 		ch <- prometheus.MustNewConstMetric(
 			c.socketCurrentConnectionsDesc, prometheus.GaugeValue,
 			float64(unit.currentConnections), unit.Name)
+		ch <- prometheus.MustNewConstMetric(
+			c.socketRefusedConnectionsDesc, prometheus.GaugeValue,
+			float64(unit.refusedConnections), unit.Name)
 	}
 	return nil
 }
@@ -193,6 +201,7 @@ type unit struct {
 	nRestarts           uint32
 	acceptedConnections uint32
 	currentConnections  uint32
+	refusedConnections  uint32
 }
 
 func (c *systemdCollector) getAllUnits() ([]unit, error) {
@@ -244,6 +253,12 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
 			}
 			unit.currentConnections = currentConnectionCount.Value.Value().(uint32)
 
+			refusedConnectionCount, err := conn.GetUnitTypeProperty(unit.Name, "Socket", "NRefused")
+			if err != nil {
+				log.Debugf("couldn't get unit '%s' NRefused: %s\n", unit.Name, err)
+				continue
+			}
+			unit.refusedConnections = refusedConnectionCount.Value.Value().(uint32)
 		}
 
 		result = append(result, unit)