- move filter creation to function

- created a bool such that we only compile the filter on the first gather
- no longer collecting errors but rather displaying them as we go along
- Changelog updated

CHANGELOG.md

@@ -59,6 +59,7 @@ be deprecated eventually.
 - [#2501](https://github.com/influxdata/telegraf/pull/2501): Support DEAD(X) state in system input plugin.
 - [#2522](https://github.com/influxdata/telegraf/pull/2522): Add support for mongodb client certificates.
 - [#1948](https://github.com/influxdata/telegraf/pull/1948): Support adding SNMP table indexes as tags.
+- [#2425](https://github.com/influxdata/telegraf/pull/2425): Support to include/exclude docker container labels as tags
 
 ### Bugfixes
 

plugins/inputs/docker/docker.go

@@ -40,7 +40,8 @@ type Docker struct {
 	client      *client.Client
 	engine_host string
 
-	testing bool
+	testing             bool
+	labelFiltersCreated bool
 }
 
 // infoWrapper wraps client.Client.List for testing.
@@ -146,22 +147,13 @@ func (d *Docker) Gather(acc telegraf.Accumulator) error {
 		}
 		d.client = c
 	}
-
-	// Create label filters
-	if len(d.LabelInclude) != 0 {
-		var err error
-		d.LabelFilter.labelInclude, err = filter.Compile(d.LabelInclude)
-		if err != nil {
-			return err
-		}
-	}
-
-	if len(d.LabelExclude) != 0 {
-		var err error
-		d.LabelFilter.labelExclude, err = filter.Compile(d.LabelExclude)
+	// Create label filters if not already created
+	if !d.labelFiltersCreated {
+		err := d.createLabelFilters()
 		if err != nil {
 			return err
 		}
+		d.labelFiltersCreated = true
 	}
 
 	// Get daemon info
@@ -633,11 +625,32 @@ func parseSize(sizeStr string) (int64, error) {
 	return int64(size), nil
 }
 
+func (d *Docker) createLabelFilters() error {
+	if len(d.LabelInclude) != 0 && d.LabelFilter.labelInclude == nil {
+		var err error
+		d.LabelFilter.labelInclude, err = filter.Compile(d.LabelInclude)
+		if err != nil {
+			return err
+		}
+	}
+
+	if len(d.LabelExclude) != 0 && d.LabelFilter.labelExclude == nil {
+		var err error
+		d.LabelFilter.labelExclude, err = filter.Compile(d.LabelExclude)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func init() {
 	inputs.Add("docker", func() telegraf.Input {
 		return &Docker{
-			PerDevice: true,
-			Timeout:   internal.Duration{Duration: time.Second * 5},
+			PerDevice:           true,
+			Timeout:             internal.Duration{Duration: time.Second * 5},
+			labelFiltersCreated: false,
 		}
 	})
 }

plugins/inputs/docker/docker_test.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/influxdata/telegraf/testutil"
 
-	"fmt"
 	"github.com/docker/docker/api/types"
 	"github.com/stretchr/testify/require"
 )
@@ -280,23 +279,19 @@ func TestDockerGatherLabels(t *testing.T) {
 		err := d.Gather(&acc)
 		require.NoError(t, err)
 
-		var expectedErrors []string
 		for _, label := range tt.expected {
 			if !acc.HasTag("docker_container_cpu", label) {
-				expectedErrors = append(expectedErrors, fmt.Sprintf("%s ", label))
+				t.Errorf("Didn't get expected label of %s.  Test was:  Include: %s  Exclude %s",
+					label, tt.include, tt.exclude)
 			}
 		}
 
-		var notexpectedErrors []string
 		for _, label := range tt.notexpected {
 			if acc.HasTag("docker_container_cpu", label) {
-				notexpectedErrors = append(notexpectedErrors, fmt.Sprintf("%s ", label))
+				t.Errorf("Got unexpected label of %s.  Test was:  Include: %s  Exclude %s",
+					label, tt.include, tt.exclude)
 			}
 		}
-
-		if len(expectedErrors) > 0 || len(notexpectedErrors) > 0 {
-			t.Errorf("Failed test for: Include: %s  Exclude:  %s", tt.include, tt.exclude)
-		}
 	}
 }