Add white/blacklisting of units for systemd collector

collector/systemd_linux_test.go

@@ -14,6 +14,7 @@
 package collector
 
 import (
+	"regexp"
 	"testing"
 
 	"github.com/coreos/go-systemd/dbus"
@@ -47,6 +48,30 @@ func getUnitListFixtures() [][]dbus.UnitStatus {
 			JobType:     "",
 			JobPath:     "/",
 		},
+		dbus.UnitStatus{
+			Name:        "foobar",
+			Description: "bar desc",
+			LoadState:   "not-found",
+			ActiveState: "inactive",
+			SubState:    "dead",
+			Followed:    "",
+			Path:        "/org/freedesktop/systemd1/unit/bar",
+			JobId:       0,
+			JobType:     "",
+			JobPath:     "/",
+		},
+		dbus.UnitStatus{
+			Name:        "baz",
+			Description: "bar desc",
+			LoadState:   "not-found",
+			ActiveState: "inactive",
+			SubState:    "dead",
+			Followed:    "",
+			Path:        "/org/freedesktop/systemd1/unit/bar",
+			JobId:       0,
+			JobType:     "",
+			JobPath:     "/",
+		},
 	}
 
 	fixture2 := []dbus.UnitStatus{}
@@ -72,3 +97,27 @@ func TestSystemdCollectorDoesntCrash(t *testing.T) {
 		collector.collectUnitStatusMetrics(sink, units)
 	}
 }
+
+func TestSystemdIgnoreFilter(t *testing.T) {
+	fixtures := getUnitListFixtures()
+	whitelistPattern := regexp.MustCompile("foo")
+	blacklistPattern := regexp.MustCompile("bar")
+	filtered := filterUnits(fixtures[0], whitelistPattern, blacklistPattern)
+	for _, unit := range filtered {
+		if blacklistPattern.MatchString(unit.Name) || !whitelistPattern.MatchString(unit.Name) {
+			t.Error(unit.Name, "should not be in the filtered list")
+		}
+	}
+}
+func TestSystemdIgnoreFilterDefaultKeepsAll(t *testing.T) {
+	c, err := NewSystemdCollector()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fixtures := getUnitListFixtures()
+	collector := c.(*systemdCollector)
+	filtered := filterUnits(fixtures[0], collector.unitWhitelistPattern, collector.unitBlacklistPattern)
+	if len(filtered) != len(fixtures[0]) {
+		t.Error("Default filters removed units")
+	}
+}