diff --git a/cmd/uncloud/service/run.go b/cmd/uncloud/service/run.go
index c72b1cf4..06727a73 100644
--- a/cmd/uncloud/service/run.go
+++ b/cmd/uncloud/service/run.go
@@ -68,8 +68,8 @@ func NewRunCommand() *cobra.Command {
 	cmd.Flags().StringSliceVarP(&opts.publish, "publish", "p", nil,
 		"Publish a service port to make it accessible outside the cluster. Can be specified multiple times.\n"+
 			"Format: [hostname:][load_balancer_port:]container_port[/protocol] or [host_ip:]:host_port:container_port[/protocol]@host\n"+
-			"Supported protocols: tcp, udp, http, https (default is tcp). If a hostname for http(s) port is not specified,\n"+
-			"service-name.cluster-domain will be used as the hostname.\n"+
+			"Supported protocols: tcp, udp, http, https (default is tcp). If a hostname for http(s) port is not specified\n"+
+			"and a cluster domain is reserved, service-name.cluster-domain will be used as the hostname.\n"+
 			"Examples:\n"+
 			"  -p 8080/https                  Publish port 8080 as HTTPS via load balancer with default service-name.cluster-domain hostname\n"+
 			"  -p app.example.com:8080/https  Publish port 8080 as HTTPS via load balancer with custom hostname\n"+
diff --git a/pkg/api/service.go b/pkg/api/service.go
index ab61c7ee..3aa39005 100644
--- a/pkg/api/service.go
+++ b/pkg/api/service.go
@@ -115,7 +115,8 @@ type ContainerSpec struct {
 	// PullPolicy determines when to pull the image from the registry or use the image already available in the cluster.
 	// Default is PullPolicyMissing if empty.
 	PullPolicy string
-	// List of volumes to bind mount into the container.
+	// Volumes is list of data volumes to mount into the container.
+	// TODO: replace with []VolumeSpec
 	Volumes []string
 }
 
diff --git a/pkg/api/volume.go b/pkg/api/volume.go
new file mode 100644
index 00000000..f7c67c22
--- /dev/null
+++ b/pkg/api/volume.go
@@ -0,0 +1,51 @@
+package api
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/docker/docker/api/types/mount"
+)
+
+const (
+	// VolumeTypeBind is the type for mounting a host path.
+	VolumeTypeBind = "bind"
+	// VolumeTypeVolume is the type for mounting a managed volume.
+	VolumeTypeVolume = "volume"
+	// VolumeTypeTmpfs is the type for mounting a temporary file system stored in the host memory.
+	VolumeTypeTmpfs = "tmpfs"
+
+	// SELinuxShared share the volume content.
+	SELinuxShared = "z"
+	// SELinuxUnshared label content as private unshared.
+	SELinuxUnshared = "Z"
+)
+
+type VolumeSpec struct {
+	Type     string
+	Source   string
+	Target   string
+	ReadOnly bool
+	Bind     *VolumeBind
+	// TODO: add options for tmpfs.
+}
+
+type VolumeBind struct {
+	CreateHostPath bool
+	Propagation    mount.Propagation
+	SELinux        string
+}
+
+func (v *VolumeSpec) Validate() error {
+	switch v.Type {
+	case VolumeTypeBind, VolumeTypeVolume:
+	default:
+		return fmt.Errorf("invalid volume type: '%s'", v.Type)
+	}
+
+	if !strings.HasPrefix(v.Target, "/") {
+		return fmt.Errorf("invalid volume target: '%s', must be an absolute path in the container", v.Target)
+	}
+
+	return nil
+}