graphite parser, handle multiple templates empty filter

Previously, the graphite parser would simply overwrite any template that
had an identical filter to a previous template. This included the empty
filter.

This change automatically creates a "*." filter for any template
specified with an empty filter. This allows users to specify only a
template, and Telegraf will auto-match based on the most specific
template.

closes #1731

plugins/parsers/graphite/parser.go

@@ -57,38 +57,34 @@ func NewGraphiteParser(
 	defaultTemplate, _ := NewTemplate("measurement*", nil, p.Separator)
 	matcher.AddDefaultTemplate(defaultTemplate)
 
+	tmplts := parsedTemplates{}
 	for _, pattern := range p.Templates {
-		template := pattern
-		filter := ""
+		tmplt := parsedTemplate{}
+		tmplt.template = pattern
 		// Format is [filter] <template> [tag1=value1,tag2=value2]
 		parts := strings.Fields(pattern)
 		if len(parts) < 1 {
 			continue
 		} else if len(parts) >= 2 {
 			if strings.Contains(parts[1], "=") {
-				template = parts[0]
+				tmplt.template = parts[0]
+				tmplt.tagstring = parts[1]
 			} else {
-				filter = parts[0]
-				template = parts[1]
-			}
-		}
-
-		// Parse out the default tags specific to this template
-		tags := map[string]string{}
-		if strings.Contains(parts[len(parts)-1], "=") {
-			tagStrs := strings.Split(parts[len(parts)-1], ",")
-			for _, kv := range tagStrs {
-				parts := strings.Split(kv, "=")
-				tags[parts[0]] = parts[1]
+				tmplt.filter = parts[0]
+				tmplt.template = parts[1]
+				if len(parts) > 2 {
+					tmplt.tagstring = parts[2]
+				}
 			}
 		}
+		tmplts = append(tmplts, tmplt)
+	}
 
-		tmpl, err1 := NewTemplate(template, tags, p.Separator)
-		if err1 != nil {
-			err = err1
-			break
+	sort.Sort(tmplts)
+	for _, tmplt := range tmplts {
+		if err := p.addToMatcher(tmplt); err != nil {
+			return nil, err
 		}
-		matcher.Add(filter, tmpl)
 	}
 
 	if err != nil {
@@ -98,6 +94,24 @@ func NewGraphiteParser(
 	}
 }
 
+func (p *GraphiteParser) addToMatcher(tmplt parsedTemplate) error {
+	// Parse out the default tags specific to this template
+	tags := map[string]string{}
+	if tmplt.tagstring != "" {
+		for _, kv := range strings.Split(tmplt.tagstring, ",") {
+			parts := strings.Split(kv, "=")
+			tags[parts[0]] = parts[1]
+		}
+	}
+
+	tmpl, err := NewTemplate(tmplt.template, tags, p.Separator)
+	if err != nil {
+		return err
+	}
+	p.matcher.Add(tmplt.filter, tmpl)
+	return nil
+}
+
 func (p *GraphiteParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 	// parse even if the buffer begins with a newline
 	buf = bytes.TrimPrefix(buf, []byte("\n"))
@@ -465,3 +479,30 @@ func (n *nodes) Less(j, k int) bool {
 
 func (n *nodes) Swap(i, j int) { (*n)[i], (*n)[j] = (*n)[j], (*n)[i] }
 func (n *nodes) Len() int      { return len(*n) }
+
+type parsedTemplate struct {
+	template  string
+	filter    string
+	tagstring string
+}
+type parsedTemplates []parsedTemplate
+
+func (e parsedTemplates) Less(j, k int) bool {
+	if len(e[j].filter) == 0 && len(e[k].filter) == 0 {
+		nj := len(strings.Split(e[j].template, "."))
+		nk := len(strings.Split(e[k].template, "."))
+		return nj < nk
+	}
+	if len(e[j].filter) == 0 {
+		return true
+	}
+	if len(e[k].filter) == 0 {
+		return false
+	}
+
+	nj := len(strings.Split(e[j].template, "."))
+	nk := len(strings.Split(e[k].template, "."))
+	return nj < nk
+}
+func (e parsedTemplates) Swap(i, j int) { e[i], e[j] = e[j], e[i] }
+func (e parsedTemplates) Len() int      { return len(e) }

plugins/parsers/graphite/parser_test.go

@@ -747,6 +747,48 @@ func TestApplyTemplateGreedyField(t *testing.T) {
 	}
 }
 
+func TestApplyTemplateOverSpecific(t *testing.T) {
+	p, err := NewGraphiteParser(
+		".",
+		[]string{
+			"measurement.host.metric.metric.metric",
+		},
+		nil,
+	)
+	assert.NoError(t, err)
+
+	measurement, tags, _, err := p.ApplyTemplate("net.server001.a.b 2")
+	assert.Equal(t, "net", measurement)
+	assert.Equal(t,
+		map[string]string{"host": "server001", "metric": "a.b"},
+		tags)
+}
+
+func TestApplyTemplateMostSpecificTemplate(t *testing.T) {
+	p, err := NewGraphiteParser(
+		".",
+		[]string{
+			"measurement.host.metric",
+			"measurement.host.metric.metric.metric",
+			"measurement.host.metric.metric",
+		},
+		nil,
+	)
+	assert.NoError(t, err)
+
+	measurement, tags, _, err := p.ApplyTemplate("net.server001.a.b.c 2")
+	assert.Equal(t, "net", measurement)
+	assert.Equal(t,
+		map[string]string{"host": "server001", "metric": "a.b.c"},
+		tags)
+
+	measurement, tags, _, err = p.ApplyTemplate("net.server001.a.b 2")
+	assert.Equal(t, "net", measurement)
+	assert.Equal(t,
+		map[string]string{"host": "server001", "metric": "a.b"},
+		tags)
+}
+
 // Test Helpers
 func errstr(err error) string {
 	if err != nil {