Add type for namespaces for better UI

This adds `type Namespaces []Namespace` so that methods can be added to
this slice so that it is easier for consumers to work with the values.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

config.go

@@ -17,6 +17,39 @@ type Namespace struct {
 	Path string `json:"path,omitempty"`
 }
 
+type Namespaces []Namespace
+
+func (n Namespaces) Exists(name string) bool {
+	return n.index(name) != -1
+}
+
+func (n Namespaces) Remove(name string) bool {
+	i := n.index(name)
+	if i == -1 {
+		return false
+	}
+	n = append(n[:i], n[i+1:]...)
+	return true
+}
+
+func (n Namespaces) Add(name, path string) {
+	i := n.index(name)
+	if i == -1 {
+		n = append(n, Namespace{Name: name, Path: path})
+		return
+	}
+	n[i].Path = path
+}
+
+func (n Namespaces) index(name string) int {
+	for i, ns := range n {
+		if ns.Name == name {
+			return i
+		}
+	}
+	return -1
+}
+
 // Config defines configuration options for executing a process inside a contained environment.
 type Config struct {
 	// Mount specific options.
@@ -45,7 +78,7 @@ type Config struct {
 
 	// Namespaces specifies the container's namespaces that it should setup when cloning the init process
 	// If a namespace is not provided that namespace is shared from the container's parent process
-	Namespaces []Namespace `json:"namespaces,omitempty"`
+	Namespaces Namespaces `json:"namespaces,omitempty"`
 
 	// Capabilities specify the capabilities to keep when executing the process inside the container
 	// All capbilities not specified will be dropped from the processes capability mask

integration/exec_test.go

@@ -4,8 +4,6 @@ import (
 	"os"
 	"strings"
 	"testing"
-
-	"github.com/docker/libcontainer"
 )
 
 func TestExecPS(t *testing.T) {
@@ -88,8 +86,7 @@ func TestIPCHost(t *testing.T) {
 	}
 
 	config := newTemplateConfig(rootfs)
-	i := getNamespaceIndex(config, "NEWIPC")
-	config.Namespaces = append(config.Namespaces[:i], config.Namespaces[i+1:]...)
+	config.Namespaces.Remove("NEWIPC")
 	buffers, exitCode, err := runContainer(config, "", "readlink", "/proc/self/ns/ipc")
 	if err != nil {
 		t.Fatal(err)
@@ -121,8 +118,7 @@ func TestIPCJoinPath(t *testing.T) {
 	}
 
 	config := newTemplateConfig(rootfs)
-	i := getNamespaceIndex(config, "NEWIPC")
-	config.Namespaces[i].Path = "/proc/1/ns/ipc"
+	config.Namespaces.Add("NEWIPC", "/proc/1/ns/ipc")
 
 	buffers, exitCode, err := runContainer(config, "", "readlink", "/proc/self/ns/ipc")
 	if err != nil {
@@ -150,8 +146,7 @@ func TestIPCBadPath(t *testing.T) {
 	defer remove(rootfs)
 
 	config := newTemplateConfig(rootfs)
-	i := getNamespaceIndex(config, "NEWIPC")
-	config.Namespaces[i].Path = "/proc/1/ns/ipcc"
+	config.Namespaces.Add("NEWIPC", "/proc/1/ns/ipcc")
 
 	_, _, err = runContainer(config, "", "true")
 	if err == nil {
@@ -179,12 +174,3 @@ func TestRlimit(t *testing.T) {
 		t.Fatalf("expected rlimit to be 1024, got %s", limit)
 	}
 }
-
-func getNamespaceIndex(config *libcontainer.Config, name string) int {
-	for i, v := range config.Namespaces {
-		if v.Name == name {
-			return i
-		}
-	}
-	return -1
-}