Add support for dangling filter to volumes

The dangling filter determine whether a volume is dangling - IE,
it has no containers attached using it. Unlike our other filters,
this one is a boolean - must be true or false, not arbitrary
values.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 11 insertions, 1 deletions

diff --git a/libpod/volume.go b/libpod/volume.go
index 82f389833..b29ac7ddf 100644
--- a/libpod/volume.go
+++ b/libpod/volume.go
@@ -137,7 +137,7 @@ func (v *Volume) Config() (*VolumeConfig, error) {
 
 // VolumeInUse goes through the container dependencies of a volume
 // and checks if the volume is being used by any container.
-func (v *Volume) VolumesInUse() ([]string, error) {
+func (v *Volume) VolumeInUse() ([]string, error) {
 	v.lock.Lock()
 	defer v.lock.Unlock()
 
@@ -146,3 +146,13 @@ func (v *Volume) VolumesInUse() ([]string, error) {
 	}
 	return v.runtime.state.VolumeInUse(v)
 }
+
+// IsDangling returns whether this volume is dangling (unused by any
+// containers).
+func (v *Volume) IsDangling() (bool, error) {
+	ctrs, err := v.VolumeInUse()
+	if err != nil {
+		return false, err
+	}
+	return len(ctrs) == 0, nil
+}