pkg/ocicni: a cross-platform namespace manager thing

Signed-off-by: Vincent Batts <[email protected]>

pkg/ocicni/ocicni.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"os/exec"
 	"sort"
 	"strings"
 	"sync"
@@ -21,7 +20,7 @@ type cniNetworkPlugin struct {
 	sync.RWMutex
 	defaultNetwork *cniNetwork
 
-	nsenterPath        string
+	nsManager          *nsManager
 	pluginDir          string
 	cniDirs            []string
 	vendorCNIDirPrefix string
@@ -170,11 +169,11 @@ func InitCNI(pluginDir string, cniDirs ...string) (CNIPlugin, error) {
 		pods:               make(map[string]*podLock),
 	}
 
-	var err error
-	plugin.nsenterPath, err = exec.LookPath("nsenter")
+	nsm, err := newNSManager()
 	if err != nil {
 		return nil, err
 	}
+	plugin.nsManager = nsm
 
 	// Ensure plugin directory exists, because the following monitoring logic
 	// relies on that.
@@ -352,9 +351,9 @@ func (plugin *cniNetworkPlugin) GetPodNetworkStatus(podNetwork PodNetwork) (stri
 	plugin.podLock(podNetwork).Lock()
 	defer plugin.podUnlock(podNetwork)
 
-	ip, err := getContainerIP(plugin.nsenterPath, podNetwork.NetNS, DefaultInterfaceName, "-4")
+	ip, err := getContainerIP(plugin.nsManager, podNetwork.NetNS, DefaultInterfaceName, "-4")
 	if err != nil {
-		ip, err = getContainerIP(plugin.nsenterPath, podNetwork.NetNS, DefaultInterfaceName, "-6")
+		ip, err = getContainerIP(plugin.nsManager, podNetwork.NetNS, DefaultInterfaceName, "-6")
 	}
 	if err != nil {
 		return "", err

pkg/ocicni/util.go

@@ -1,32 +1,8 @@
 package ocicni
 
-import (
-	"fmt"
-	"net"
-	"os/exec"
-	"strings"
-)
-
-func getContainerIP(nsenterPath, netnsPath, interfaceName, addrType string) (net.IP, error) {
-	// Try to retrieve ip inside container network namespace
-	output, err := exec.Command(nsenterPath, fmt.Sprintf("--net=%s", netnsPath), "-F", "--",
-		"ip", "-o", addrType, "addr", "show", "dev", interfaceName, "scope", "global").CombinedOutput()
-	if err != nil {
-		return nil, fmt.Errorf("Unexpected command output %s with error: %v", output, err)
-	}
-
-	lines := strings.Split(string(output), "\n")
-	if len(lines) < 1 {
-		return nil, fmt.Errorf("Unexpected command output %s", output)
-	}
-	fields := strings.Fields(lines[0])
-	if len(fields) < 4 {
-		return nil, fmt.Errorf("Unexpected address output %s ", lines[0])
-	}
-	ip, _, err := net.ParseCIDR(fields[3])
-	if err != nil {
-		return nil, fmt.Errorf("CNI failed to parse ip from output %s due to %v", output, err)
-	}
-
-	return ip, nil
+// newNSManager initializes a new namespace manager, which is a platform dependent struct.
+func newNSManager() (*nsManager, error) {
+	nsm := &nsManager{}
+	err := nsm.init()
+	return nsm, err
 }

pkg/ocicni/util_linux.go

@@ -0,0 +1,46 @@
+// +build linux
+
+package ocicni
+
+import (
+	"fmt"
+	"net"
+	"os/exec"
+	"strings"
+)
+
+var defaultNamespaceEnterCommandName = "nsenter"
+
+type nsManager struct {
+	nsenterPath string
+}
+
+func (nsm *nsManager) init() error {
+	var err error
+	nsm.nsenterPath, err = exec.LookPath(defaultNamespaceEnterCommandName)
+	return err
+}
+
+func getContainerIP(nsm *nsManager, netnsPath, interfaceName, addrType string) (net.IP, error) {
+	// Try to retrieve ip inside container network namespace
+	output, err := exec.Command(nsm.nsenterPath, fmt.Sprintf("--net=%s", netnsPath), "-F", "--",
+		"ip", "-o", addrType, "addr", "show", "dev", interfaceName, "scope", "global").CombinedOutput()
+	if err != nil {
+		return nil, fmt.Errorf("Unexpected command output %s with error: %v", output, err)
+	}
+
+	lines := strings.Split(string(output), "\n")
+	if len(lines) < 1 {
+		return nil, fmt.Errorf("Unexpected command output %s", output)
+	}
+	fields := strings.Fields(lines[0])
+	if len(fields) < 4 {
+		return nil, fmt.Errorf("Unexpected address output %s ", lines[0])
+	}
+	ip, _, err := net.ParseCIDR(fields[3])
+	if err != nil {
+		return nil, fmt.Errorf("CNI failed to parse ip from output %s due to %v", output, err)
+	}
+
+	return ip, nil
+}

pkg/ocicni/util_unsupported.go

@@ -0,0 +1,19 @@
+// +build !linux
+
+package ocicni
+
+import (
+	"fmt"
+	"net"
+)
+
+type nsManager struct {
+}
+
+func (nsm *nsManager) init() error {
+	return nil
+}
+
+func getContainerIP(nsm *nsManager, netnsPath, interfaceName, addrType string) (net.IP, error) {
+	return nil, fmt.Errorf("not supported yet")
+}