Change systemd unit filtering (#1083)

* Change systemd unit filtering

Get all units from systemd and filter in Go.
* Improves compatibility with older versions of systemd.
* Improve debugging by printing when units pass the filter.
* Remove extraneous newlines from log messages.

Signed-off-by: Ben Kochie <superq@gmail.com>

3 files changed, 12 insertions, 9 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a119177..e02195f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ Darwin meminfo metrics have been renamed to match Prometheus conventions. #1060
 * [BUGFIX] Systemd units will not be ignored if you're running older versions of systemd #1039
 * [BUGFIX] Handle vanishing PIDs #1043
 * [BUGFIX] Correctly cast Darwin memory info #1060
+* [BUGFIX] Filter systemd units in Go for compatibility with older versions #1083
 
 ## 0.16.0 / 2018-05-15
 
diff --git a/collector/systemd_linux.go b/collector/systemd_linux.go
index 7140b7b..dd8a3f0 100644
--- a/collector/systemd_linux.go
+++ b/collector/systemd_linux.go
@@ -228,7 +228,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
         defer conn.Close()
 
         // Filter out any units that are not installed and are pulled in only as dependencies.
-        allUnits, err := conn.ListUnitsFiltered([]string{"loaded"})
+        allUnits, err := conn.ListUnits()
 
         if err != nil {
                 return nil, err
@@ -243,7 +243,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
                 if strings.HasSuffix(unit.Name, ".timer") {
                         lastTriggerValue, err := conn.GetUnitTypeProperty(unit.Name, "Timer", "LastTriggerUSec")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' LastTriggerUSec: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' LastTriggerUSec: %s", unit.Name, err)
                                 continue
                         }
 
@@ -253,7 +253,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
                         // NRestarts wasn't added until systemd 235.
                         restartsCount, err := conn.GetUnitTypeProperty(unit.Name, "Service", "NRestarts")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' NRestarts: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' NRestarts: %s", unit.Name, err)
                         } else {
                                 nRestarts := restartsCount.Value.Value().(uint32)
                                 unit.nRestarts = &nRestarts
@@ -263,7 +263,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
                 if strings.HasSuffix(unit.Name, ".socket") {
                         acceptedConnectionCount, err := conn.GetUnitTypeProperty(unit.Name, "Socket", "NAccepted")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' NAccepted: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' NAccepted: %s", unit.Name, err)
                                 continue
                         }
 
@@ -271,7 +271,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
 
                         currentConnectionCount, err := conn.GetUnitTypeProperty(unit.Name, "Socket", "NConnections")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' NConnections: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' NConnections: %s", unit.Name, err)
                                 continue
                         }
                         unit.currentConnections = currentConnectionCount.Value.Value().(uint32)
@@ -279,7 +279,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
                         // NRefused wasn't added until systemd 239.
                         refusedConnectionCount, err := conn.GetUnitTypeProperty(unit.Name, "Socket", "NRefused")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' NRefused: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' NRefused: %s", unit.Name, err)
                         } else {
                                 nRefused := refusedConnectionCount.Value.Value().(uint32)
                                 unit.refusedConnections = &nRefused
@@ -291,7 +291,7 @@ func (c *systemdCollector) getAllUnits() ([]unit, error) {
                 } else {
                         timestampValue, err := conn.GetUnitProperty(unit.Name, "ActiveEnterTimestamp")
                         if err != nil {
-                                log.Debugf("couldn't get unit '%s' StartTimeUsec: %s\n", unit.Name, err)
+                                log.Debugf("couldn't get unit '%s' StartTimeUsec: %s", unit.Name, err)
                                 continue
                         }
 
@@ -321,7 +321,8 @@ func summarizeUnits(units []unit) map[string]float64 {
 func filterUnits(units []unit, whitelistPattern, blacklistPattern *regexp.Regexp) []unit {
         filtered := make([]unit, 0, len(units))
         for _, unit := range units {
-                if whitelistPattern.MatchString(unit.Name) && !blacklistPattern.MatchString(unit.Name) {
+                if whitelistPattern.MatchString(unit.Name) && !blacklistPattern.MatchString(unit.Name) && unit.LoadState == "loaded" {
+                        log.Debugf("Adding unit: %s", unit.Name)
                         filtered = append(filtered, unit)
                 } else {
                         log.Debugf("Ignoring unit: %s", unit.Name)
diff --git a/collector/systemd_linux_test.go b/collector/systemd_linux_test.go
index 3d7d7f6..26257aa 100644
--- a/collector/systemd_linux_test.go
+++ b/collector/systemd_linux_test.go
@@ -126,7 +126,8 @@ func TestSystemdIgnoreFilterDefaultKeepsAll(t *testing.T) {
         fixtures := getUnitListFixtures()
         collector := c.(*systemdCollector)
         filtered := filterUnits(fixtures[0], collector.unitWhitelistPattern, collector.unitBlacklistPattern)
-        if len(filtered) != len(fixtures[0]) {
+        // Adjust fixtures by 3 "not-found" units.
+        if len(filtered) != len(fixtures[0])-3 {
                 t.Error("Default filters removed units")
         }
 }