Check if tag value is empty before allocation

closes #2390
closes #2404

CHANGELOG.md

@@ -61,6 +61,7 @@ be deprecated eventually.
 - [#2341](https://github.com/influxdata/telegraf/issues/2341): telegraf swallowing panics in --test mode.
 - [#2358](https://github.com/influxdata/telegraf/pull/2358): Create pidfile with 644 permissions & defer file deletion.
 - [#2282](https://github.com/influxdata/telegraf/issues/2282): Reloading telegraf freezes prometheus output.
+- [#2390](https://github.com/influxdata/telegraf/issues/2390): Empty tag value causes error on InfluxDB output.
 
 ## v1.2.1 [2017-02-01]
 

metric/metric.go

@@ -44,13 +44,18 @@ func New(
 	// pre-allocate exact size of the tags slice
 	taglen := 0
 	for k, v := range tags {
-		// TODO check that length of tag key & value are > 0
+		if len(k) == 0 || len(v) == 0 {
+			continue
+		}
 		taglen += 2 + len(escape(k, "tagkey")) + len(escape(v, "tagval"))
 	}
 	m.tags = make([]byte, taglen)
 
 	i := 0
 	for k, v := range tags {
+		if len(k) == 0 || len(v) == 0 {
+			continue
+		}
 		m.tags[i] = ','
 		i++
 		i += copy(m.tags[i:], escape(k, "tagkey"))

metric/metric_test.go

@@ -625,3 +625,26 @@ func TestNewMetricFailNaN(t *testing.T) {
 	_, err := New("cpu", tags, fields, now)
 	assert.NoError(t, err)
 }
+
+func TestEmptyTagValueOrKey(t *testing.T) {
+	now := time.Now()
+
+	tags := map[string]string{
+		"host":     "localhost",
+		"emptytag": "",
+		"":         "valuewithoutkey",
+	}
+	fields := map[string]interface{}{
+		"usage_idle": float64(99),
+	}
+	m, err := New("cpu", tags, fields, now)
+
+	assert.True(t, m.HasTag("host"))
+	assert.False(t, m.HasTag("emptytag"))
+	assert.Equal(t,
+		fmt.Sprintf("cpu,host=localhost usage_idle=99 %d\n", now.UnixNano()),
+		m.String())
+
+	assert.NoError(t, err)
+
+}

plugins/inputs/prometheus/parser_test.go

@@ -114,8 +114,6 @@ func TestParseValidPrometheus(t *testing.T) {
 		"osVersion":     "CentOS Linux 7 (Core)",
 		"dockerVersion": "1.8.2",
 		"kernelVersion": "3.10.0-229.20.1.el7.x86_64",
-		"cadvisorRevision": "",
-		"cadvisorVersion":  "",
 	}, metrics[0].Tags())
 
 	// Counter value

plugins/parsers/nagios/parser_test.go

@@ -67,7 +67,7 @@ func TestParseValidOutput(t *testing.T) {
 	assert.Equal(t, map[string]interface{}{
 		"value": float64(0.008457),
 	}, metrics[0].Fields())
-	assert.Equal(t, map[string]string{"unit": ""}, metrics[0].Tags())
+	assert.Equal(t, map[string]string{}, metrics[0].Tags())
 }
 
 func TestParseInvalidOutput(t *testing.T) {