Added feature for placement key in v3

it will map `engine.labels.operatingsystem` to `beta.kubernetes.io/os` and
`node.hostname` to `kubernetes.io/hostname` and all other constraints will not be supported.

pkg/kobject/kobject.go

@@ -103,6 +103,7 @@ type ServiceConfig struct {
 	GroupAdd        []int64             `compose:"group_add"`
 	Volumes         []Volumes           `compose:""`
 	HealthChecks    HealthCheck         `compose:""`
+	Placement       map[string]string   `compose:""`
 }
 
 // HealthCheck the healthcheck configuration for a service

pkg/loader/compose/v3.go

@@ -294,6 +294,20 @@ func dockerComposeToKomposeMapping(composeObject *types.Config) (kobject.Kompose
 			serviceConfig.Replicas = int(*composeServiceConfig.Deploy.Replicas)
 		}
 
+		// placement:
+		placement := make(map[string]string)
+		for _, j := range composeServiceConfig.Deploy.Placement.Constraints {
+			p := strings.Split(j, " == ")
+			if p[0] == "node.hostname" {
+				placement["kubernetes.io/hostname"] = p[1]
+			} else if p[0] == "engine.labels.operatingsystem" {
+				placement["beta.kubernetes.io/os"] = p[1]
+			} else {
+				log.Warn(p[0], " constraints in placement is not supported, only 'node.hostname' and 'engine.labels.operatingsystem' is only supported as a constraint ")
+			}
+		}
+		serviceConfig.Placement = placement
+
 		// TODO: Build is not yet supported, see:
 		// https://github.com/docker/cli/blob/master/cli/compose/types/types.go#L9
 		// We will have to *manually* add this / parse.

pkg/transformer/kubernetes/k8sutils.go

@@ -380,7 +380,7 @@ func (k *Kubernetes) UpdateKubernetesObjects(name string, service kobject.Servic
 		template.Spec.Containers[0].Stdin = service.Stdin
 		template.Spec.Containers[0].TTY = service.Tty
 		template.Spec.Volumes = volumes
-
+		template.Spec.NodeSelector = service.Placement
 		// Configure the HealthCheck
 		// We check to see if it's blank
 		if !reflect.DeepEqual(service.HealthChecks, kobject.HealthCheck{}) {