POC: allow to add labels for docker containers from job metadata

client/driver/docker.go

@@ -14,6 +14,7 @@ import (
 	"github.com/hashicorp/nomad/client/allocdir"
 	"github.com/hashicorp/nomad/client/config"
 	"github.com/hashicorp/nomad/client/driver/args"
+	"github.com/hashicorp/nomad/client/driver/environment"
 	"github.com/hashicorp/nomad/client/fingerprint"
 	"github.com/hashicorp/nomad/nomad/structs"
 )
@@ -43,6 +44,10 @@ func NewDockerDriver(ctx *DriverContext) Driver {
 	return &DockerDriver{DriverContext: *ctx}
 }
 
+const (
+	labelPrefix = environment.MetaPrefix + "LABEL_"
+)
+
 // dockerClient creates *docker.Client. In test / dev mode we can use ENV vars
 // to connect to the docker daemon. In production mode we will read
 // docker.endpoint from the config file.
@@ -266,9 +271,12 @@ func (d *DockerDriver) createContainer(ctx *ExecContext, task *structs.Task) (do
 	env.SetAllocDir(filepath.Join("/", allocdir.SharedAllocName))
 	env.SetTaskLocalDir(filepath.Join("/", allocdir.TaskLocal))
 
+	envVars, labels := splitEnvVarsLabels(env.List())
+
 	config := &docker.Config{
-		Env:   env.List(),
-		Image: task.Config["image"],
+		Env:    envVars,
+		Labels: labels,
+		Image:  task.Config["image"],
 	}
 
 	rawArgs, hasArgs := task.Config["args"]
@@ -557,3 +565,20 @@ func (h *dockerHandle) run() {
 	}
 	close(h.waitCh)
 }
+
+// splitEnvVarsLabels returns environment vars and labels to set on the container
+func splitEnvVarsLabels(envVars []string) ([]string, map[string]string) {
+	var envs []string
+	labels := make(map[string]string)
+
+	for _, value := range envVars {
+		if strings.HasPrefix(value, labelPrefix) {
+			parts := strings.SplitN(value, "=", 2)
+			labels[strings.TrimPrefix(parts[0], labelPrefix)] = parts[1]
+		} else {
+			envs = append(envs, value)
+		}
+	}
+
+	return envs, labels
+}

client/driver/docker_test.go

@@ -432,3 +432,39 @@ func TestDockerHostNet(t *testing.T) {
 	}
 	defer handle.Kill()
 }
+
+func TestsSlitEnvVarsLabels(t *testing.T) {
+
+	environment := []string{
+		"NOMAD_IP=1.1.1.1",
+		"NOMAD_CPU_LIMIT=500",
+		"NOMAD_META_TEST1=true_one",
+		"NOMAD_META_LABEL_LAB1=one",
+		"NOMAD_META_TEST2=test_two",
+		"NOMAD_META_LABEL_LAB2=two",
+		"NOMAD_META_TEST3=true_three",
+		"NOMAD_META_LABEL_LAB3=three",
+		"NOMAD_MEMORY_LIMIT=1024",
+	}
+
+	envVars, labels := splitEnvVarsLabels(environment)
+	if got, want := len(envVars), 6; got != want {
+		t.Errorf("Error on len. Got: %v. Expect %v items.", got, want)
+	}
+	if got, want := len(labels), 3; got != want {
+		t.Errorf("Error on len. Got: %v. Expect %v items.", got, want)
+	}
+	if got, want := envVars[3], environment[4]; got != want {
+		t.Errorf("Error. Got: '%v'. Expect '%v'.", got, want)
+	}
+	if got, want := envVars[4], environment[6]; got != want {
+		t.Errorf("Error. Got: '%v'. Expect '%v'.", got, want)
+	}
+	if got, want := labels["LAB2"], "two"; got != want {
+		t.Errorf("Error. Got: '%v'. Expect '%v'.", got, want)
+	}
+	if got, want := labels["LAB3"], "three"; got != want {
+		t.Errorf("Error. Got: '%v'. Expect '%v'.", got, want)
+	}
+
+}