pkg/ns: remove namespace creation (and move to testutils)

Namespace creation had an unergonomic interface and isn't used, except
for testing code. Remove it; downstream users should really be creating
their own namespaces

pkg/ns/ns_linux.go

@@ -15,10 +15,8 @@
 package ns
 
 import (
-	"crypto/rand"
 	"fmt"
 	"os"
-	"path"
 	"runtime"
 	"sync"
 	"syscall"
@@ -38,82 +36,6 @@ func getCurrentThreadNetNSPath() string {
 	return fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid())
 }
 
-// Creates a new persistent network namespace and returns an object
-// representing that namespace, without switching to it
-func NewNS() (NetNS, error) {
-	const nsRunDir = "/var/run/netns"
-
-	b := make([]byte, 16)
-	_, err := rand.Reader.Read(b)
-	if err != nil {
-		return nil, fmt.Errorf("failed to generate random netns name: %v", err)
-	}
-
-	err = os.MkdirAll(nsRunDir, 0755)
-	if err != nil {
-		return nil, err
-	}
-
-	// create an empty file at the mount point
-	nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
-	nsPath := path.Join(nsRunDir, nsName)
-	mountPointFd, err := os.Create(nsPath)
-	if err != nil {
-		return nil, err
-	}
-	mountPointFd.Close()
-
-	// Ensure the mount point is cleaned up on errors; if the namespace
-	// was successfully mounted this will have no effect because the file
-	// is in-use
-	defer os.RemoveAll(nsPath)
-
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	// do namespace work in a dedicated goroutine, so that we can safely
-	// Lock/Unlock OSThread without upsetting the lock/unlock state of
-	// the caller of this function
-	var fd *os.File
-	go (func() {
-		defer wg.Done()
-		runtime.LockOSThread()
-
-		var origNS NetNS
-		origNS, err = GetNS(getCurrentThreadNetNSPath())
-		if err != nil {
-			return
-		}
-		defer origNS.Close()
-
-		// create a new netns on the current thread
-		err = unix.Unshare(unix.CLONE_NEWNET)
-		if err != nil {
-			return
-		}
-		defer origNS.Set()
-
-		// bind mount the new netns from the current thread onto the mount point
-		err = unix.Mount(getCurrentThreadNetNSPath(), nsPath, "none", unix.MS_BIND, "")
-		if err != nil {
-			return
-		}
-
-		fd, err = os.Open(nsPath)
-		if err != nil {
-			return
-		}
-	})()
-	wg.Wait()
-
-	if err != nil {
-		unix.Unmount(nsPath, unix.MNT_DETACH)
-		return nil, fmt.Errorf("failed to create namespace: %v", err)
-	}
-
-	return &netNS{file: fd, mounted: true}, nil
-}
-
 func (ns *netNS) Close() error {
 	if err := ns.errorIfClosed(); err != nil {
 		return err
@@ -124,16 +46,6 @@ func (ns *netNS) Close() error {
 	}
 	ns.closed = true
 
-	if ns.mounted {
-		if err := unix.Unmount(ns.file.Name(), unix.MNT_DETACH); err != nil {
-			return fmt.Errorf("Failed to unmount namespace %s: %v", ns.file.Name(), err)
-		}
-		if err := os.RemoveAll(ns.file.Name()); err != nil {
-			return fmt.Errorf("Failed to clean up namespace %s: %v", ns.file.Name(), err)
-		}
-		ns.mounted = false
-	}
-
 	return nil
 }
 
@@ -180,9 +92,8 @@ type NetNS interface {
 }
 
 type netNS struct {
-	file    *os.File
-	mounted bool
-	closed  bool
+	file   *os.File
+	closed bool
 }
 
 // netNS implements the NetNS interface