Merge pull request #241 from szook/protect-against-empty-result-set

protect against empty wmi query result sets

collector/ad.go

@@ -3,6 +3,8 @@
 package collector
 
 import (
+	"errors"
+
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -616,6 +618,9 @@ func (c *ADCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, er
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.AddressBookOperationsTotal,

collector/cs.go

@@ -4,6 +4,8 @@
 package collector
 
 import (
+	"errors"
+
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -60,6 +62,9 @@ func (c *CSCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, er
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.LogicalProcessors,

collector/dns.go

@@ -4,6 +4,8 @@
 package collector
 
 import (
+	"errors"
+
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -237,6 +239,9 @@ func (c *DNSCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, e
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.ZoneTransferRequestsReceived,

collector/iis.go

@@ -7,6 +7,7 @@
 package collector
 
 import (
+	"errors"
 	"fmt"
 	"regexp"
 
@@ -1738,7 +1739,10 @@ func (c *IISCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, e
 		return nil, err
 	}
 
-	if len(dst_cache) > 0 {
+	if len(dst_cache) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
+
 	ch <- prometheus.MustNewConstMetric(
 		c.ServiceCache_ActiveFlushedEntries,
 		prometheus.GaugeValue,
@@ -1947,7 +1951,6 @@ func (c *IISCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, e
 		prometheus.CounterValue,
 		float64(dst_cache[0].OutputCacheTotalFlushes),
 	)
-	}
 
 	return nil, nil
 }

collector/mssql.go

@@ -1769,7 +1769,10 @@ func (c *MSSQLCollector) collectAccessMethods(ch chan<- prometheus.Metric, sqlIn
 		return nil, err
 	}
 
-	if len(dst) > 0 {
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
+
 	v := dst[0]
 	ch <- prometheus.MustNewConstMetric(
 		c.AccessMethodsAUcleanupbatches,
@@ -2071,7 +2074,6 @@ func (c *MSSQLCollector) collectAccessMethods(ch chan<- prometheus.Metric, sqlIn
 		float64(v.WorktablesFromCacheRatio),
 		sqlInstance,
 	)
-	}
 	return nil, nil
 }
 
@@ -2201,8 +2203,10 @@ func (c *MSSQLCollector) collectBufferManager(ch chan<- prometheus.Metric, sqlIn
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
-	if len(dst) > 0 {
 	v := dst[0]
 
 	ch <- prometheus.MustNewConstMetric(
@@ -2358,7 +2362,7 @@ func (c *MSSQLCollector) collectBufferManager(ch chan<- prometheus.Metric, sqlIn
 		float64(v.Targetpages),
 		sqlInstance,
 	)
-	}
+
 	return nil, nil
 }
 
@@ -2998,8 +3002,10 @@ func (c *MSSQLCollector) collectGeneralStatistics(ch chan<- prometheus.Metric, s
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
-	if len(dst) > 0 {
 	v := dst[0]
 	ch <- prometheus.MustNewConstMetric(
 		c.GenStatsActiveTempTables,
@@ -3168,7 +3174,7 @@ func (c *MSSQLCollector) collectGeneralStatistics(ch chan<- prometheus.Metric, s
 		float64(v.UserConnections),
 		sqlInstance,
 	)
-	}
+
 	return nil, nil
 }
 
@@ -3280,8 +3286,10 @@ func (c *MSSQLCollector) collectMemoryManager(ch chan<- prometheus.Metric, sqlIn
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
-	if len(dst) > 0 {
 	v := dst[0]
 
 	ch <- prometheus.MustNewConstMetric(
@@ -3423,7 +3431,7 @@ func (c *MSSQLCollector) collectMemoryManager(ch chan<- prometheus.Metric, sqlIn
 		float64(v.TotalServerMemoryKB*1024),
 		sqlInstance,
 	)
-	}
+
 	return nil, nil
 }
 
@@ -3451,7 +3459,10 @@ func (c *MSSQLCollector) collectSQLStats(ch chan<- prometheus.Metric, sqlInstanc
 		return nil, err
 	}
 
-	if len(dst) > 0 {
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
+
 	v := dst[0]
 
 	ch <- prometheus.MustNewConstMetric(
@@ -3530,6 +3541,6 @@ func (c *MSSQLCollector) collectSQLStats(ch chan<- prometheus.Metric, sqlInstanc
 		float64(v.UnsafeAutoParamsPersec),
 		sqlInstance,
 	)
-	}
+
 	return nil, nil
 }

collector/os.go

@@ -4,6 +4,7 @@
 package collector
 
 import (
+	"errors"
 	"time"
 
 	"github.com/StackExchange/wmi"
@@ -142,6 +143,10 @@ func (c *OSCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, er
 		return nil, err
 	}
 
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
+
 	ch <- prometheus.MustNewConstMetric(
 		c.PhysicalMemoryFreeBytes,
 		prometheus.GaugeValue,

collector/system.go

@@ -4,6 +4,7 @@
 package collector
 
 import (
+	"errors"
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -94,6 +95,9 @@ func (c *SystemCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.ContextSwitchesTotal,

collector/tcp.go

@@ -5,6 +5,7 @@
 package collector
 
 import (
+	"errors"
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -118,6 +119,9 @@ func (c *TCPCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, e
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	// Counters
 	ch <- prometheus.MustNewConstMetric(

collector/vmware.go

@@ -2,6 +2,8 @@
 package collector
 
 import (
+	"errors"
+
 	"github.com/StackExchange/wmi"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
@@ -201,6 +203,9 @@ func (c *VmwareCollector) collectMem(ch chan<- prometheus.Metric) (*prometheus.D
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.MemActive,
@@ -287,6 +292,9 @@ func (c *VmwareCollector) collectCpu(ch chan<- prometheus.Metric) (*prometheus.D
 	if err := wmi.Query(q, &dst); err != nil {
 		return nil, err
 	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
 
 	ch <- prometheus.MustNewConstMetric(
 		c.CpuLimitMHz,