Filter on all container names, use proper name

Resolves #4376

plugins/inputs/docker/docker.go

@@ -366,9 +366,22 @@ func (d *Docker) gatherContainer(
 	var v *types.StatsJSON
 	// Parse container name
 	cname := "unknown"
-	if len(container.Names) > 0 {
+	match := false
-		// Not sure what to do with other names, just take the first.
+	if len(container.Names) == 0 { // for tests
-		cname = strings.TrimPrefix(container.Names[0], "/")
+		match = true
+	}
+
+	for i := range container.Names {
+		if !match {
+			match = d.containerFilter.Match(strings.TrimPrefix(container.Names[i], "/"))
+			if match {
+				cname = strings.TrimPrefix(container.Names[i], "/")
+			}
+		}
+	}
+
+	if !match {
+		return nil
 	}
 
 	// the image name sometimes has a version part, or a private repo
@@ -391,10 +404,6 @@ func (d *Docker) gatherContainer(
 		"container_version": imageVersion,
 	}
 
-	if !d.containerFilter.Match(cname) {
-		return nil
-	}
-
 	ctx, cancel := context.WithTimeout(context.Background(), d.Timeout.Duration)
 	defer cancel()
 	r, err := d.client.ContainerStats(ctx, container.ID, false)
@@ -411,6 +420,11 @@ func (d *Docker) gatherContainer(
 	}
 	daemonOSType := r.OSType
 
+	// use common (printed at `docker ps`) name for container
+	if cname != strings.TrimPrefix(v.Name, "/") && v.Name != "" {
+		tags["container_name"] = strings.TrimPrefix(v.Name, "/")
+	}
+
 	// Add labels to tags
 	for k, label := range container.Labels {
 		if d.labelFilter.Match(k) {
@@ -461,12 +475,12 @@ func (d *Docker) gatherContainer(
 		acc.AddFields("docker_container_health", healthfields, tags, time.Now())
 	}
 
-	gatherContainerStats(v, acc, tags, container.ID, d.PerDevice, d.Total, daemonOSType)
+	parseContainerStats(v, acc, tags, container.ID, d.PerDevice, d.Total, daemonOSType)
 
 	return nil
 }
 
-func gatherContainerStats(
+func parseContainerStats(
 	stat *types.StatsJSON,
 	acc telegraf.Accumulator,
 	tags map[string]string,

plugins/inputs/docker/docker_test.go

@@ -107,7 +107,7 @@ func TestDockerGatherContainerStats(t *testing.T) {
 		"container_image": "redis/image",
 	}
 
-	gatherContainerStats(stats, &acc, tags, "123456789", true, true, "linux")
+	parseContainerStats(stats, &acc, tags, "123456789", true, true, "linux")
 
 	// test docker_container_net measurement
 	netfields := map[string]interface{}{

plugins/processors/regex/regex.go

@@ -34,7 +34,7 @@ const sampleConfig = `
   #   key = "request"
   #   ## All the power of the Go regular expressions available here
   #   ## For example, named subgroups
-  #   pattern = "^/api(?P<method>/[\\w/]+)\\S*"
+  #   pattern = "^/api(?P<method>/[\\w/]+)\\S*" 
   #   replacement = "${method}"
   #   ## If result_key is present, a new field will be created
   #   ## instead of changing existing field
@@ -67,10 +67,7 @@ func (r *Regex) Apply(in ...telegraf.Metric) []telegraf.Metric {
 	for _, metric := range in {
 		for _, converter := range r.Tags {
 			if value, ok := metric.GetTag(converter.Key); ok {
-				k, v := r.convert(converter, value)
+				metric.AddTag(r.convert(converter, value))
-				if k != "" {
-					metric.AddTag(k, v)
-				}
 			}
 		}
 
@@ -78,10 +75,7 @@ func (r *Regex) Apply(in ...telegraf.Metric) []telegraf.Metric {
 			if value, ok := metric.GetField(converter.Key); ok {
 				switch value := value.(type) {
 				case string:
-					k, _ := r.convert(converter, value)
+					metric.AddField(r.convert(converter, value))
-					if k != "" {
-						metric.AddField(r.convert(converter, value))
-					}
 				}
 			}
 		}