Added container_labels parameter

CHANGELOG.md

@@ -21,6 +21,7 @@ time before a new metric is included by the plugin.
 
 - [#1247](https://github.com/influxdata/telegraf/pull/1247): rollbar input plugin. Thanks @francois2metz and @cduez!
 - [#1208](https://github.com/influxdata/telegraf/pull/1208): Standardized AWS credentials evaluation & wildcard CloudWatch dimensions. Thanks @johnrengelman!
+- [#1263](https://github.com/influxdata/telegraf/issues/1263): Added container_labels to docker plugin
 
 ### Bugfixes
 

plugins/inputs/docker/README.md

@@ -22,6 +22,9 @@ for the stat structure can be found
   endpoint = "unix:///var/run/docker.sock"
   # Only collect metrics for these containers, collect all if empty
   container_names = []
+  ## Only collect these container labels from docker daemon, collect all if empty but note that
+  ## this will break prometheus output if containers have inconsistent label sets.
+  container_labels = []
 ```
 
 ### Measurements & Fields:

plugins/inputs/docker/docker.go

@@ -24,6 +24,7 @@ import (
 type Docker struct {
 	Endpoint        string
 	ContainerNames  []string
+	ContainerLabels []string
 	Timeout         internal.Duration
 
 	client DockerClient
@@ -56,6 +57,9 @@ var sampleConfig = `
   endpoint = "unix:///var/run/docker.sock"
   ## Only collect metrics for these containers, collect all if empty
   container_names = []
+  ## Only collect these container labels from docker daemon, collect all if empty but note that
+  ## this will break prometheus output if containers have inconsistent label sets.
+  container_labels = []
   ## Timeout for docker list, info, and stats commands
   timeout = "5s"
 `
@@ -232,10 +236,22 @@ func (d *Docker) gatherContainer(
 		return fmt.Errorf("Error decoding: %s", err.Error())
 	}
 
-	// Add labels to tags
+	// Check if there are container labels specified
+	if len(d.ContainerLabels) == 0 {
+		// Add all labels to tags
 		for k, label := range container.Labels {
 			tags[k] = label
 		}
+	} else {
+		// Omit labels not in d.ContainerLabels and add placeholders for missing labels
+		for _, l := range d.ContainerLabels {
+			if label, ok := container.Labels[l]; ok {
+				tags[l] = label
+			} else {
+				tags[l] = "-"
+			}
+		}
+	}
 
 	gatherContainerStats(v, acc, tags, container.ID)