Set volume NeedsCopyUp to false iff data was copied up

Currently Docker copies up the first volume on a mountpoint with
data.

Fixes: https://github.com/containers/podman/issues/12714

Also added NeedsCopyUP, NeedsChown and MountCount to the podman volume
inspect code.

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

libpod/container_internal.go

@@ -1700,13 +1700,6 @@ func (c *Container) mountNamedVolume(v *ContainerNamedVolume, mountpoint string)
 	if vol.state.NeedsCopyUp {
 		logrus.Debugf("Copying up contents from container %s to volume %s", c.ID(), vol.Name())
 
-		// Set NeedsCopyUp to false immediately, so we don't try this
-		// again when there are already files copied.
-		vol.state.NeedsCopyUp = false
-		if err := vol.save(); err != nil {
-			return nil, err
-		}
-
 		// If the volume is not empty, we should not copy up.
 		volMount := vol.mountPoint()
 		contents, err := ioutil.ReadDir(volMount)
@@ -1753,6 +1746,13 @@ func (c *Container) mountNamedVolume(v *ContainerNamedVolume, mountpoint string)
 			return vol, nil
 		}
 
+		// Set NeedsCopyUp to false since we are about to do first copy
+		// Do not copy second time.
+		vol.state.NeedsCopyUp = false
+		if err := vol.save(); err != nil {
+			return nil, err
+		}
+
 		// Buildah Copier accepts a reader, so we'll need a pipe.
 		reader, writer := io.Pipe()
 		defer reader.Close()

libpod/define/volume_inspect.go

@@ -48,4 +48,12 @@ type InspectVolumeData struct {
 	// volume for a specific container, and will be be removed when any
 	// container using it is removed.
 	Anonymous bool `json:"Anonymous,omitempty"`
+	// MountCount is the number of times this volume has been mounted.
+	MountCount uint `json:"MountCount"`
+	// NeedsCopyUp indicates that the next time the volume is mounted into
+	NeedsCopyUp bool `json:"NeedsCopyUp,omitempty"`
+	// NeedsChown indicates that the next time the volume is mounted into
+	// a container, the container will chown the volume to the container process
+	// UID/GID.
+	NeedsChown bool `json:"NeedsChown,omitempty"`
 }

libpod/volume_inspect.go

@@ -60,6 +60,9 @@ func (v *Volume) Inspect() (*define.InspectVolumeData, error) {
 	data.UID = v.uid()
 	data.GID = v.gid()
 	data.Anonymous = v.config.IsAnon
+	data.MountCount = v.state.MountCount
+	data.NeedsCopyUp = v.state.NeedsCopyUp
+	data.NeedsChown = v.state.NeedsChown
 
 	return data, nil
 }

test/system/160-volumes.bats

@@ -345,4 +345,44 @@ EOF
     is "$output" "tmpfs" "volume should be tmpfs"
 }
 
+# Named volumes copyup
+@test "podman volume create copyup" {
+    myvolume=myvol$(random_string)
+    mylabel=$(random_string)
+
+    # Create a named volume
+    run_podman volume create $myvolume
+    is "$output" "$myvolume" "output from volume create"
+
+    # Confirm that it shows up in 'volume ls', and confirm values
+    run_podman volume ls --format json
+    tests="
+Name           | $myvolume
+Driver         | local
+NeedsCopyUp    | true
+NeedsChown    | true
+"
+    parse_table "$tests" | while read field expect; do
+        actual=$(jq -r ".[0].$field" <<<"$output")
+        is "$actual" "$expect" "volume ls .$field"
+    done
+
+    run_podman run --rm --volume $myvolume:/vol $IMAGE true
+    run_podman volume inspect --format '{{ .NeedsCopyUp }}' $myvolume
+    is "${output}" "true" "If content in dest '/vol' empty NeedsCopyUP should still be true"
+    run_podman volume inspect --format '{{ .NeedsChown }}' $myvolume
+    is "${output}" "false" "After first use within a container NeedsChown should still be false"
+
+    run_podman run --rm --volume $myvolume:/etc $IMAGE ls /etc/passwd
+    run_podman volume inspect --format '{{ .NeedsCopyUp }}' $myvolume
+    is "${output}" "false" "If content in dest '/etc' non-empty NeedsCopyUP should still have happend and be false"
+
+    run_podman volume inspect --format '{{.Mountpoint}}' $myvolume
+    mountpoint="$output"
+    test -e "$mountpoint/passwd"
+
+    # Clean up
+    run_podman volume rm $myvolume
+}
+
 # vim: filetype=sh