Add Docker container environment variables as tags. Only whitelisted #2580 (#2581)

plugins/inputs/docker/docker.go

@@ -31,6 +31,7 @@ type Docker struct {
 	Timeout        internal.Duration
 	PerDevice      bool     `toml:"perdevice"`
 	Total          bool     `toml:"total"`
+	TagEnvironment []string `toml:"tag_env"`
 	LabelInclude   []string `toml:"docker_label_include"`
 	LabelExclude   []string `toml:"docker_label_exclude"`
 
@@ -79,6 +80,18 @@ func statsWrapper(
 	return fc.ContainerStats(ctx, containerID, stream)
 }
 
+func inspectWrapper(
+	c *client.Client,
+	ctx context.Context,
+	containerID string,
+) (types.ContainerJSON, error) {
+	if c != nil {
+		return c.ContainerInspect(ctx, containerID)
+	}
+	fc := FakeDockerClient{}
+	return fc.ContainerInspect(ctx, containerID)
+}
+
 // KB, MB, GB, TB, PB...human friendly
 const (
 	KB = 1000
@@ -107,6 +120,8 @@ 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
+  ##tag_env = ["JAVA_HOME", "HEAP_SIZE"]
 
   ## docker labels to include and exclude as tags.  Globs accepted.
   ## Note that an empty array for both will include all labels as tags
@@ -321,6 +336,23 @@ func (d *Docker) gatherContainer(
 		}
 	}
 
+	// Add whitelisted environment variables to tags
+	if len(d.TagEnvironment) > 0 {
+		info, err := inspectWrapper(d.client, ctx, container.ID)
+		if err != nil {
+			return fmt.Errorf("Error inspecting docker container: %s", err.Error())
+		}
+		for _, envvar := range info.Config.Env {
+			for _, configvar := range d.TagEnvironment {
+				dock_env := strings.SplitN(envvar, "=", 2)
+				//check for presence of tag in whitelist
+				if len(dock_env) == 2 && len(strings.TrimSpace(dock_env[1])) != 0 && configvar == dock_env[0] {
+					tags[dock_env[0]] = dock_env[1]
+				}
+			}
+		}
+	}
+
 	gatherContainerStats(v, acc, tags, container.ID, d.PerDevice, d.Total)
 
 	return nil