Add podman volume mount support

Fixes: containers#12768

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

cmd/podman/volumes/exists.go

@@ -10,7 +10,7 @@ var (
 	volumeExistsDescription = `If the given volume exists, podman volume exists exits with 0, otherwise the exit code will be 1.`
 	volumeExistsCommand     = &cobra.Command{
 		Use:               "exists VOLUME",
-		Short:             "volume exists",
+		Short:             "Volume exists",
 		Long:              volumeExistsDescription,
 		RunE:              volumeExists,
 		Example:           `podman volume exists myvol`,

cmd/podman/volumes/mount.go

@@ -0,0 +1,51 @@
+package volumes
+
+import (
+	"fmt"
+
+	"github.com/containers/podman/v4/cmd/podman/common"
+	"github.com/containers/podman/v4/cmd/podman/registry"
+	"github.com/containers/podman/v4/cmd/podman/utils"
+	"github.com/spf13/cobra"
+)
+
+var (
+	volumeMountDescription = `Mount a volume and return the mountpoint`
+	volumeMountCommand     = &cobra.Command{
+		Annotations: map[string]string{
+			registry.UnshareNSRequired: "",
+			registry.ParentNSRequired:  "",
+			registry.EngineMode:        registry.ABIMode,
+		},
+		Use:               "mount NAME",
+		Short:             "Mount volume",
+		Long:              volumeMountDescription,
+		RunE:              volumeMount,
+		Example:           `podman volume mount myvol`,
+		Args:              cobra.ExactArgs(1),
+		ValidArgsFunction: common.AutocompleteVolumes,
+	}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Command: volumeMountCommand,
+		Parent:  volumeCmd,
+	})
+}
+
+func volumeMount(cmd *cobra.Command, args []string) error {
+	var errs utils.OutputErrors
+	reports, err := registry.ContainerEngine().VolumeMount(registry.GetContext(), args)
+	if err != nil {
+		return err
+	}
+	for _, r := range reports {
+		if r.Err == nil {
+			fmt.Println(r.Path)
+			continue
+		}
+		errs = append(errs, r.Err)
+	}
+	return errs.PrintErrors()
+}

cmd/podman/volumes/unmount.go

@@ -0,0 +1,48 @@
+package volumes
+
+import (
+	"fmt"
+
+	"github.com/containers/podman/v4/cmd/podman/common"
+	"github.com/containers/podman/v4/cmd/podman/registry"
+	"github.com/containers/podman/v4/cmd/podman/utils"
+	"github.com/spf13/cobra"
+)
+
+var (
+	volumeUnmountDescription = `Unmount a volume`
+	volumeUnmountCommand     = &cobra.Command{
+		Annotations:       map[string]string{registry.EngineMode: registry.ABIMode},
+		Use:               "unmount NAME",
+		Short:             "Unmount volume",
+		Long:              volumeUnmountDescription,
+		RunE:              volumeUnmount,
+		Example:           `podman volume unmount myvol`,
+		Args:              cobra.ExactArgs(1),
+		ValidArgsFunction: common.AutocompleteVolumes,
+	}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Command: volumeUnmountCommand,
+		Parent:  volumeCmd,
+	})
+}
+
+func volumeUnmount(cmd *cobra.Command, args []string) error {
+	var errs utils.OutputErrors
+	reports, err := registry.ContainerEngine().VolumeUnmount(registry.GetContext(), args)
+	if err != nil {
+		return err
+	}
+	for _, r := range reports {
+		var errs utils.OutputErrors
+		if r.Err == nil {
+			fmt.Println(r.Id)
+		} else {
+			errs = append(errs, r.Err)
+		}
+	}
+	return errs.PrintErrors()
+}

docs/source/markdown/podman-volume-mount.1.md

@@ -0,0 +1,28 @@
+% podman-volume-mount(1)
+
+## NAME
+podman\-volume\-mount - Mount a volume filesystem
+
+## SYNOPSIS
+**podman volume mount** [*volume* ...]
+
+## DESCRIPTION
+Mounts the specified volumes' file system in a location which can be
+accessed from the host, and returns its location.
+
+Rootless mode only supports mounting file volumes, unless you enter the user namespace
+via the `podman unshare` command. All other volume types will fail to mount.
+
+## RETURN VALUE
+The location of the mounted file system.  On error an empty string and errno is
+returned.
+
+## EXAMPLE
+
+```
+podman volume mount foo
+/home/dwalsh/.local/share/containers/storage/volumes/foo/_data
+```
+
+## SEE ALSO
+**[podman(1)](podman.1.md)**, **[podman-volume(1)](podman-volume.1.md)**, **[podman-volume-unmount(1)](podman-volume-unmount.1.md)**, **[podman-unshare(1)](podman-unshare.1.md)**, **mount(8)**

docs/source/markdown/podman-volume-unmount.1.md

@@ -0,0 +1,27 @@
+% podman-volume-unmount(1)
+
+## NAME
+podman\-volume\-unmount - Unmount a volume
+
+## SYNOPSIS
+**podman volume unmount** *volume* [...]
+
+**podman volume umount** *volume* [...]
+
+## DESCRIPTION
+Unmounts the specified volume, if there are no other containers
+using it.
+
+Volume storage increments a mount counter each time a volume is mounted.
+When a volume is unmounted, the mount counter is decremented, and the
+volume's filesystem is physically unmounted only when the mount
+counter reaches zero indicating no other processes are using the mount.
+
+## EXAMPLE
+
+podman volume unmount volumeID
+
+podman volume unmount volumeID1 volumeID2 volumeID3
+
+## SEE ALSO
+**[podman(1)](podman.1.md)**, **[podman-volume(1)](podman-volume.1.md)**, **[podman-volume-mount(1)](podman-volume-mount.1.md)**

docs/source/markdown/podman-volume.1.md

@@ -19,8 +19,10 @@ podman volume is a set of subcommands that manage volumes.
 | import  | [podman-volume-import(1)](podman-volume-import.1.md)   | Import tarball contents into a podman volume.                                  |
 | inspect | [podman-volume-inspect(1)](podman-volume-inspect.1.md) | Get detailed information on one or more volumes.                               |
 | ls      | [podman-volume-ls(1)](podman-volume-ls.1.md)           | List all the available volumes.                                                |
+| mount   | [podman-volume-mount(1)](podman-volume-mount.1.md)     | Mount a volume filesystem.                                                     |
 | prune   | [podman-volume-prune(1)](podman-volume-prune.1.md)     | Remove all unused volumes.                                                     |
 | rm      | [podman-volume-rm(1)](podman-volume-rm.1.md)           | Remove one or more volumes.                                                    |
+| unmount | [podman-volume-unmount(1)](podman-volume-unmount.1.md) | Unmount a volume.                                                     |
 
 ## SEE ALSO
 **[podman(1)](podman.1.md)**

libpod/volume.go

@@ -255,3 +255,16 @@ func (v *Volume) IsDangling() (bool, error) {
 func (v *Volume) UsesVolumeDriver() bool {
 	return !(v.config.Driver == define.VolumeDriverLocal || v.config.Driver == "")
 }
+
+func (v *Volume) Mount() (string, error) {
+	v.lock.Lock()
+	defer v.lock.Unlock()
+	err := v.mount()
+	return v.config.MountPoint, err
+}
+
+func (v *Volume) Unmount() error {
+	v.lock.Lock()
+	defer v.lock.Unlock()
+	return v.unmount(false)
+}

libpod/volume_internal_linux.go

@@ -1,3 +1,4 @@
+//go:build linux
 // +build linux
 
 package libpod

pkg/domain/entities/engine_container.go

@@ -99,6 +99,8 @@ type ContainerEngine interface {
 	VolumeMounted(ctx context.Context, namesOrID string) (*BoolReport, error)
 	VolumeInspect(ctx context.Context, namesOrIds []string, opts InspectOptions) ([]*VolumeInspectReport, []error, error)
 	VolumeList(ctx context.Context, opts VolumeListOptions) ([]*VolumeListReport, error)
+	VolumeMount(ctx context.Context, namesOrIds []string) ([]*VolumeMountReport, error)
 	VolumePrune(ctx context.Context, options VolumePruneOptions) ([]*reports.PruneReport, error)
 	VolumeRm(ctx context.Context, namesOrIds []string, opts VolumeRmOptions) ([]*VolumeRmReport, error)
+	VolumeUnmount(ctx context.Context, namesOrIds []string) ([]*VolumeUnmountReport, error)
 }

pkg/domain/entities/volumes.go

@@ -187,3 +187,17 @@ type VolumeCreateBody struct {
 	// Required: true
 	Name string `json:"Name"`
 }
+
+// VolumeMountReport describes the response from volume mount
+type VolumeMountReport struct {
+	Err  error
+	Id   string //nolint
+	Name string
+	Path string
+}
+
+// VolumeUnmountReport describes the response from umounting a volume
+type VolumeUnmountReport struct {
+	Err error
+	Id  string //nolint
+}

pkg/domain/infra/abi/volumes.go

@@ -178,3 +178,35 @@ func (ic *ContainerEngine) VolumeMounted(ctx context.Context, nameOrID string) (
 	}
 	return &entities.BoolReport{Value: false}, nil
 }
+
+func (ic *ContainerEngine) VolumeMount(ctx context.Context, nameOrIDs []string) ([]*entities.VolumeMountReport, error) {
+	reports := []*entities.VolumeMountReport{}
+	for _, name := range nameOrIDs {
+		report := entities.VolumeMountReport{Id: name}
+		vol, err := ic.Libpod.LookupVolume(name)
+		if err != nil {
+			report.Err = err
+		} else {
+			report.Path, report.Err = vol.Mount()
+		}
+		reports = append(reports, &report)
+	}
+
+	return reports, nil
+}
+
+func (ic *ContainerEngine) VolumeUnmount(ctx context.Context, nameOrIDs []string) ([]*entities.VolumeUnmountReport, error) {
+	reports := []*entities.VolumeUnmountReport{}
+	for _, name := range nameOrIDs {
+		report := entities.VolumeUnmountReport{Id: name}
+		vol, err := ic.Libpod.LookupVolume(name)
+		if err != nil {
+			report.Err = err
+		} else {
+			report.Err = vol.Unmount()
+		}
+		reports = append(reports, &report)
+	}
+
+	return reports, nil
+}

pkg/domain/infra/tunnel/volumes.go

@@ -100,3 +100,11 @@ func (ic *ContainerEngine) VolumeExists(ctx context.Context, nameOrID string) (*
 func (ic *ContainerEngine) VolumeMounted(ctx context.Context, nameOrID string) (*entities.BoolReport, error) {
 	return nil, errors.New("not implemented")
 }
+
+func (ic *ContainerEngine) VolumeMount(ctx context.Context, nameOrIDs []string) ([]*entities.VolumeMountReport, error) {
+	return nil, errors.New("mounting volumes is not supported for remote clients")
+}
+
+func (ic *ContainerEngine) VolumeUnmount(ctx context.Context, nameOrIDs []string) ([]*entities.VolumeUnmountReport, error) {
+	return nil, errors.New("unmounting volumes is not supported for remote clients")
+}

test/system/160-volumes.bats

@@ -387,4 +387,29 @@ NeedsChown    | true
     run_podman volume rm $myvolume
 }
 
+@test "podman volume mount" {
+    skip_if_remote "podman --remote volume mount not supported"
+    myvolume=myvol$(random_string)
+    myfile=myfile$(random_string)
+    mytext=$(random_string)
+
+    # Create a named volume
+    run_podman volume create $myvolume
+    is "$output" "$myvolume" "output from volume create"
+
+    if ! is_rootless ; then
+        # image mount is hard to test as a rootless user
+        # and does not work remotely
+        run_podman volume mount ${myvolume}
+        mnt=${output}
+	echo $mytext >$mnt/$myfile
+        run_podman run -v ${myvolume}:/vol:z $IMAGE cat /vol/$myfile
+	is "$output" "$mytext" "$myfile should exist within the containers volume and contain $mytext"
+        run_podman volume unmount ${myvolume}
+    else
+        run_podman 125 volume mount ${myvolume}
+	is "$output" "Error: cannot run command \"podman volume mount\" in rootless mode, must execute.*podman unshare.*first" "Should fail and complain about unshare"
+    fi
+}
+
 # vim: filetype=sh