add verifyValue func for datadog and librato, bail if no good

closes #906

plugins/outputs/datadog/datadog.go

@@ -139,6 +139,9 @@ func (d *Datadog) authenticatedUrl() string {
 func buildMetrics(m telegraf.Metric) (map[string]Point, error) {
 	ms := make(map[string]Point)
 	for k, v := range m.Fields() {
+		if !verifyValue(v) {
+			continue
+		}
 		var p Point
 		if err := p.setValue(v); err != nil {
 			return ms, fmt.Errorf("unable to extract value from Fields, %s", err.Error())
@@ -160,6 +163,14 @@ func buildTags(mTags map[string]string) []string {
 	return tags
 }
 
+func verifyValue(v interface{}) bool {
+	switch v.(type) {
+	case string:
+		return false
+	}
+	return true
+}
+
 func (p *Point) setValue(v interface{}) error {
 	switch d := v.(type) {
 	case int:

plugins/outputs/datadog/datadog_test.go

@@ -152,14 +152,6 @@ func TestBuildPoint(t *testing.T) {
 			},
 			nil,
 		},
-		{
-			testutil.TestMetric("11234.5", "test7"),
-			Point{
-				float64(time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC).Unix()),
-				11234.5,
-			},
-			fmt.Errorf("unable to extract value from Fields, undeterminable type"),
-		},
 	}
 	for _, tt := range tagtests {
 		pt, err := buildMetrics(tt.ptIn)
@@ -175,3 +167,25 @@ func TestBuildPoint(t *testing.T) {
 		}
 	}
 }
+
+func TestVerifyValue(t *testing.T) {
+	var tagtests = []struct {
+		ptIn        telegraf.Metric
+		validMetric bool
+	}{
+		{
+			testutil.TestMetric(float32(11234.5), "test1"),
+			true,
+		},
+		{
+			testutil.TestMetric("11234.5", "test2"),
+			false,
+		},
+	}
+	for _, tt := range tagtests {
+		ok := verifyValue(tt.ptIn.Fields()["value"])
+		if tt.validMetric != ok {
+			t.Errorf("%s: verification failed\n", tt.ptIn.Name())
+		}
+	}
+}