Merge pull request #8185 from rhatdan/mount

Add support for mounting external containers

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

@@ -13,7 +13,9 @@ Mounts the specified containers' root file system in a location which can be
 accessed from the host, and returns its location.
 
 If you execute the command without any arguments, Podman will list all of the
-currently mounted containers.
+currently mounted containers, including external containers. External containers are
+containers in container/storage by tools other then Podman. For example Buildah and
+CRI-O.
 
 Rootless mode only supports mounting VFS driver, unless you enter the user namespace
 via the `podman unshare` command. All other storage drivers will fail to mount.
@@ -26,7 +28,7 @@ returned.
 
 **--all**, **-a**
 
-Mount all containers.
+Mount all podman containers. (External containers will not be mounted)
 
 **--format**=*format*
 

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

@@ -22,6 +22,10 @@ container's root filesystem is physically unmounted only when the mount
 counter reaches zero indicating no other processes are using the mount.
 An unmount can be forced with the --force flag.
 
+Note: Podman can be used to unmount Podman containers as well as external containers.
+External containers are containers created in container/storage by other tools like
+Buildah and CRI-O.
+
 ## OPTIONS
 **--all**, **-a**
 

libpod/runtime_ctr.go

@@ -918,6 +918,56 @@ func (r *Runtime) PruneContainers(filterFuncs []ContainerFilter) (map[string]int
 	return prunedContainers, pruneErrors, nil
 }
 
+// MountStorageContainer mounts the storage container's root filesystem
+func (r *Runtime) MountStorageContainer(id string) (string, error) {
+	if _, err := r.GetContainer(id); err == nil {
+		return "", errors.Wrapf(define.ErrCtrExists, "ctr %s is a libpod container", id)
+	}
+	container, err := r.store.Container(id)
+	if err != nil {
+		return "", err
+	}
+	mountPoint, err := r.store.Mount(container.ID, "")
+	if err != nil {
+		return "", errors.Wrapf(err, "error mounting storage for container %s", id)
+	}
+	return mountPoint, nil
+}
+
+// UnmountStorageContainer unmounts the storage container's root filesystem
+func (r *Runtime) UnmountStorageContainer(id string, force bool) (bool, error) {
+	if _, err := r.GetContainer(id); err == nil {
+		return false, errors.Wrapf(define.ErrCtrExists, "ctr %s is a libpod container", id)
+	}
+	container, err := r.store.Container(id)
+	if err != nil {
+		return false, err
+	}
+	return r.store.Unmount(container.ID, force)
+}
+
+// MountedStorageContainer returns whether a storage container is mounted
+// along with the mount path
+func (r *Runtime) IsStorageContainerMounted(id string) (bool, string, error) {
+	var path string
+	if _, err := r.GetContainer(id); err == nil {
+		return false, "", errors.Wrapf(define.ErrCtrExists, "ctr %s is a libpod container", id)
+	}
+
+	mountCnt, err := r.storageService.MountedContainerImage(id)
+	if err != nil {
+		return false, "", err
+	}
+	mounted := mountCnt > 0
+	if mounted {
+		path, err = r.storageService.GetMountpoint(id)
+		if err != nil {
+			return false, "", err
+		}
+	}
+	return mounted, path, nil
+}
+
 // StorageContainers returns a list of containers from containers/storage that
 // are not currently known to Podman.
 func (r *Runtime) StorageContainers() ([]storage.Container, error) {

pkg/domain/infra/abi/containers.go

@@ -1058,11 +1058,23 @@ func (ic *ContainerEngine) ContainerMount(ctx context.Context, nameOrIDs []strin
 			os.Exit(ret)
 		}
 	}
-	ctrs, err := getContainersByContext(options.All, options.Latest, nameOrIDs, ic.Libpod)
+	reports := []*entities.ContainerMountReport{}
+	// Attempt to mount named containers directly from storage,
+	// this will fail and code will fall through to removing the container from libpod.`
+	names := []string{}
+	for _, ctr := range nameOrIDs {
+		report := entities.ContainerMountReport{Id: ctr}
+		if report.Path, report.Err = ic.Libpod.MountStorageContainer(ctr); report.Err != nil {
+			names = append(names, ctr)
+		} else {
+			reports = append(reports, &report)
+		}
+	}
+
+	ctrs, err := getContainersByContext(options.All, options.Latest, names, ic.Libpod)
 	if err != nil {
 		return nil, err
 	}
-	reports := make([]*entities.ContainerMountReport, 0, len(ctrs))
 	for _, ctr := range ctrs {
 		report := entities.ContainerMountReport{Id: ctr.ID()}
 		report.Path, report.Err = ctr.Mount()
@@ -1072,6 +1084,30 @@ func (ic *ContainerEngine) ContainerMount(ctx context.Context, nameOrIDs []strin
 		return reports, nil
 	}
 
+	storageCtrs, err := ic.Libpod.StorageContainers()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, sctr := range storageCtrs {
+		mounted, path, err := ic.Libpod.IsStorageContainerMounted(sctr.ID)
+		if err != nil {
+			return nil, err
+		}
+
+		var name string
+		if len(sctr.Names) > 0 {
+			name = sctr.Names[0]
+		}
+		if mounted {
+			reports = append(reports, &entities.ContainerMountReport{
+				Id:   sctr.ID,
+				Name: name,
+				Path: path,
+			})
+		}
+	}
+
 	// No containers were passed, so we send back what is mounted
 	ctrs, err = getContainersByContext(true, false, []string{}, ic.Libpod)
 	if err != nil {
@@ -1091,15 +1127,44 @@ func (ic *ContainerEngine) ContainerMount(ctx context.Context, nameOrIDs []strin
 			})
 		}
 	}
+
 	return reports, nil
 }
 
 func (ic *ContainerEngine) ContainerUnmount(ctx context.Context, nameOrIDs []string, options entities.ContainerUnmountOptions) ([]*entities.ContainerUnmountReport, error) {
-	ctrs, err := getContainersByContext(options.All, options.Latest, nameOrIDs, ic.Libpod)
+	reports := []*entities.ContainerUnmountReport{}
+	names := []string{}
+	if options.All {
+		storageCtrs, err := ic.Libpod.StorageContainers()
+		if err != nil {
+			return nil, err
+		}
+		for _, sctr := range storageCtrs {
+			mounted, _, _ := ic.Libpod.IsStorageContainerMounted(sctr.ID)
+			if mounted {
+				report := entities.ContainerUnmountReport{Id: sctr.ID}
+				if _, report.Err = ic.Libpod.UnmountStorageContainer(sctr.ID, options.Force); report.Err != nil {
+					if errors.Cause(report.Err) != define.ErrCtrExists {
+						reports = append(reports, &report)
+					}
+				} else {
+					reports = append(reports, &report)
+				}
+			}
+		}
+	}
+	for _, ctr := range nameOrIDs {
+		report := entities.ContainerUnmountReport{Id: ctr}
+		if _, report.Err = ic.Libpod.UnmountStorageContainer(ctr, options.Force); report.Err != nil {
+			names = append(names, ctr)
+		} else {
+			reports = append(reports, &report)
+		}
+	}
+	ctrs, err := getContainersByContext(options.All, options.Latest, names, ic.Libpod)
 	if err != nil {
 		return nil, err
 	}
-	reports := []*entities.ContainerUnmountReport{}
 	for _, ctr := range ctrs {
 		state, err := ctr.State()
 		if err != nil {

test/system/060-mount.bats

@@ -2,7 +2,6 @@
 
 load helpers
 
-
 @test "podman mount - basic test" {
     # Only works with root (FIXME: does it work with rootless + vfs?)
     skip_if_rootless "mount does not work rootless"
@@ -151,4 +150,34 @@ load helpers
     run_podman rm -f $cid
 }
 
+@test "podman mount external container - basic test" {
+    # Only works with root (FIXME: does it work with rootless + vfs?)
+    skip_if_rootless "mount does not work rootless"
+    skip_if_remote "mounting remote is meaningless"
+
+    # Create a container that podman does not know about
+    external_cid=$(buildah from $IMAGE)
+
+    run_podman mount $external_cid
+    mount_path=$output
+
+    # Test image will always have this file, and will always have the tag
+    test -d $mount_path
+    is $(< "$mount_path/home/podman/testimage-id") "$PODMAN_TEST_IMAGE_TAG"  \
+       "Contents of well-known file in image"
+
+    # Make sure that 'podman mount' (no args) returns the expected path
+    run_podman mount --notruncate
+
+    reported_mountpoint=$(echo "$output" | awk '{print $2}')
+    is $reported_mountpoint $mount_path "mountpoint reported by 'podman mount'"
+
+    # umount, and make sure files are gone
+    run_podman umount $external_cid
+    if [ -d "$mount_path" ]; then
+        die "'podman umount' did not umount"
+    fi
+    buildah rm $external_cid
+}
+
 # vim: filetype=sh