Support nfs local volume mounts

Allow users to create volumes with nfs shares.

These volumes will get mounted when the first container gets started
and then will remain mounted until the system reboots or the volume is
removed.

Signed-off-by: Daniel J Walsh <[email protected]>

cmd/podman/volume_create.go

@@ -25,8 +25,8 @@ var (
 			return volumeCreateCmd(&volumeCreateCommand)
 		},
 		Example: `podman volume create myvol
-  podman volume create
-  podman volume create --label foo=bar myvol`,
+  podman volume create --label foo=bar
+  podman volume create --opt type=nfs --opt o=addr=192.168.0.2,rw --opt device=:/nfsshare  mynfsvol`,
 	}
 )
 

docs/podman-volume-create.1.md

@@ -29,7 +29,13 @@ Set metadata for a volume (e.g., --label mykey=value).
 
 **-o**, **--opt**=[]
 
-Set driver specific options.
+Set driver specific options. To setup NFS volume you need to specify:
+
+    type: `-o type=nfs` To indicate the nfs mount.
+
+    o: `-o o=addr=nfsserver.example.com,rw` Options including the address of the nfs server.
+
+    device: `-o device=/nfsshare`, the remote nfs share.
 
 ## EXAMPLES
 
@@ -39,6 +45,8 @@ $ podman volume create myvol
 $ podman volume create
 
 $ podman volume create --label foo=bar myvol
+
+# podman volume create --opt type=nfs --opt o=addr=192.168.0.2,rw --opt device=/nfsshare  mynfsvol
 ```
 
 ## SEE ALSO

libpod/runtime_ctr.go

@@ -191,6 +191,13 @@ func (r *Runtime) newContainer(ctx context.Context, rSpec *spec.Spec, options ..
 			return nil, errors.Wrapf(err, "error creating named volume %q", vol.Name)
 		}
 
+		options := newVol.Options()
+		if len(options) > 0 {
+			if err := newVol.Mount(); err != nil {
+				return nil, err
+			}
+		}
+
 		if err := ctr.copyWithTarFromImage(vol.Dest, newVol.MountPoint()); err != nil && !os.IsNotExist(err) {
 			return nil, errors.Wrapf(err, "Failed to copy content into new volume mount %q", vol.Name)
 		}

libpod/volume.go

@@ -1,5 +1,13 @@
 package libpod
 
+import (
+	"net"
+	"strings"
+
+	"github.com/containers/storage/pkg/mount"
+	"github.com/pkg/errors"
+)
+
 // Volume is the type used to create named volumes
 // TODO: all volumes should be created using this and the Volume API
 type Volume struct {
@@ -70,3 +78,57 @@ func (v *Volume) Scope() string {
 func (v *Volume) IsCtrSpecific() bool {
 	return v.config.IsCtrSpecific
 }
+
+// Mount the volume
+func (v *Volume) Mount() error {
+	if v.MountPoint() == "" {
+		return errors.Errorf("missing device in volume options")
+	}
+	mounted, err := mount.Mounted(v.MountPoint())
+	if err != nil {
+		return errors.Wrapf(err, "failed to determine if %v is mounted", v.Name())
+	}
+	if mounted {
+		return nil
+	}
+	options := v.Options()
+	if len(options) == 0 {
+		return errors.Errorf("volume %v is not mountable, no options available", v.Name())
+	}
+	mountOpts := options["o"]
+	device := options["device"]
+	if options["type"] == "nfs" {
+		if addrValue := getAddress(mountOpts); addrValue != "" && net.ParseIP(addrValue).To4() == nil {
+			ipAddr, err := net.ResolveIPAddr("ip", addrValue)
+			if err != nil {
+				return errors.Wrapf(err, "error resolving passed in nfs address")
+			}
+			mountOpts = strings.Replace(mountOpts, "addr="+addrValue, "addr="+ipAddr.String(), 1)
+		}
+		if device[0] != ':' {
+			device = ":" + device
+		}
+	}
+	err = mount.Mount(device, v.MountPoint(), options["type"], mountOpts)
+	return errors.Wrap(err, "failed to mount local volume")
+}
+
+// Unmount the volume from the system
+func (v *Volume) Unmount() error {
+	if v.MountPoint() == "" {
+		return errors.Errorf("missing device in volume options")
+	}
+	return mount.Unmount(v.MountPoint())
+}
+
+// getAddress finds out address/hostname from options
+func getAddress(opts string) string {
+	optsList := strings.Split(opts, ",")
+	for i := 0; i < len(optsList); i++ {
+		if strings.HasPrefix(optsList[i], "addr=") {
+			addr := strings.SplitN(optsList[i], "=", 2)[1]
+			return addr
+		}
+	}
+	return ""
+}

libpod/volume_internal.go

@@ -18,5 +18,6 @@ func newVolume(runtime *Runtime) (*Volume, error) {
 
 // teardownStorage deletes the volume from volumePath
 func (v *Volume) teardownStorage() error {
+	v.Unmount()
 	return os.RemoveAll(filepath.Join(v.runtime.config.VolumePath, v.Name()))
 }