Add Docker container environment variables as tags. Only whitelisted envvars will be processed.

plugins/inputs/docker/README.md

@@ -22,6 +22,8 @@ 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 = []
+  # Which environment variables should we use as a tag
+  gather_environment = ["ENV", "DC"]
 ```
 
 ### Measurements & Fields:

plugins/inputs/docker/docker.go

@@ -22,11 +22,12 @@ import (
 
 // Docker object
 type Docker struct {
-	Endpoint       string
-	ContainerNames []string
-	Timeout        internal.Duration
-	PerDevice      bool `toml:"perdevice"`
-	Total          bool `toml:"total"`
+	Endpoint          string
+	ContainerNames    []string
+	Timeout           internal.Duration
+	PerDevice         bool     `toml:"perdevice"`
+	Total             bool     `toml:"total"`
+	GatherEnvironment []string `toml:"gather_environment"`
 
 	client      DockerClient
 	engine_host string
@@ -37,6 +38,7 @@ type DockerClient interface {
 	Info(ctx context.Context) (types.Info, error)
 	ContainerList(ctx context.Context, options types.ContainerListOptions) ([]types.Container, error)
 	ContainerStats(ctx context.Context, containerID string, stream bool) (io.ReadCloser, error)
+	ContainerInspect(ctx context.Context, containerID string) (types.ContainerJSON, error)
 }
 
 // KB, MB, GB, TB, PB...human friendly
@@ -67,6 +69,8 @@ var sampleConfig = `
   perdevice = true
   ## Whether to report for each container total blkio and network stats or not
   total = false
+  ## Which environment variables should we use as a tag
+  gather_environment = ["ENV", "DC"]
 
 `
 
@@ -261,6 +265,22 @@ func (d *Docker) gatherContainer(
 		tags[k] = label
 	}
 
+	// Add whitelisted environment variables to tags
+	if len(d.GatherEnvironment) > 0 {
+		info, err := d.client.ContainerInspect(ctx, container.ID)
+		if err != nil {
+			return fmt.Errorf("Error getting docker container inspect: %s", err.Error())
+		}
+
+		for _, envvar := range info.Config.Env {
+			kvs := strings.SplitN(envvar, "=", 2)
+			if !sliceContains(kvs[0], d.GatherEnvironment) {
+				continue
+			}
+			tags[kvs[0]] = kvs[1]
+		}
+	}
+
 	gatherContainerStats(v, acc, tags, container.ID, d.PerDevice, d.Total)
 
 	return nil

plugins/inputs/docker/docker_test.go

@@ -10,6 +10,7 @@ import (
 	"golang.org/x/net/context"
 
 	"github.com/docker/engine-api/types"
+	"github.com/docker/engine-api/types/container"
 	"github.com/docker/engine-api/types/registry"
 	"github.com/influxdata/telegraf/testutil"
 
@@ -384,10 +385,24 @@ func (d FakeDockerClient) ContainerStats(ctx context.Context, containerID string
 	return stat, nil
 }
 
+func (d FakeDockerClient) ContainerInspect(ctx context.Context, containerID string) (types.ContainerJSON, error) {
+	json := types.ContainerJSON{
+		Config: &container.Config{
+			Env: []string{
+				"ENVVAR1=loremipsum",
+				"ENVVAR2=dolorsitamet",
+				"PATH=/bin:/sbin",
+			},
+		},
+	}
+
+	return json, nil
+}
+
 func TestDockerGatherInfo(t *testing.T) {
 	var acc testutil.Accumulator
 	client := FakeDockerClient{}
-	d := Docker{client: client}
+	d := Docker{client: client, GatherEnvironment: []string{"ENVVAR1", "ENVVAR2"}}
 
 	err := d.Gather(&acc)
 
@@ -433,6 +448,8 @@ func TestDockerGatherInfo(t *testing.T) {
 			"cpu":               "cpu3",
 			"container_version": "v2.2.2",
 			"engine_host":       "absol",
+			"ENVVAR1":           "loremipsum",
+			"ENVVAR2":           "dolorsitamet",
 		},
 	)
 	acc.AssertContainsTaggedFields(t,
@@ -479,6 +496,8 @@ func TestDockerGatherInfo(t *testing.T) {
 			"container_name":    "etcd2",
 			"container_image":   "quay.io/coreos/etcd",
 			"container_version": "v2.2.2",
+			"ENVVAR1":           "loremipsum",
+			"ENVVAR2":           "dolorsitamet",
 		},
 	)