add podman container|image exists

Add an exists subcommand to podman container and podman image that allows
users to verify the existence of a container or image by ID or name.  The return
code can be 0 (success), 1 (failed to find), or 125 (failed to work with runtime).

Issue #1845

Signed-off-by: baude <bbaude@redhat.com>

2 files changed, 17 insertions, 2 deletions

diff --git a/libpod/image/errors.go b/libpod/image/errors.go
new file mode 100644
index 000000000..4088946cb
--- /dev/null
+++ b/libpod/image/errors.go
@@ -0,0 +1,15 @@
+package image
+
+import (
+	"errors"
+)
+
+// Copied directly from libpod errors to avoid circular imports
+var (
+	// ErrNoSuchCtr indicates the requested container does not exist
+	ErrNoSuchCtr = errors.New("no such container")
+	// ErrNoSuchPod indicates the requested pod does not exist
+	ErrNoSuchPod = errors.New("no such pod")
+	// ErrNoSuchImage indicates the requested image does not exist
+	ErrNoSuchImage = errors.New("no such image")
+)
diff --git a/libpod/image/image.go b/libpod/image/image.go
index 7e520d97e..a05c15160 100644
--- a/libpod/image/image.go
+++ b/libpod/image/image.go
@@ -252,7 +252,7 @@ func (i *Image) getLocalImage() (*storage.Image, error) {
 	// The image has a registry name in it and we made sure we looked for it locally
 	// with a tag.  It cannot be local.
 	if decomposedImage.hasRegistry {
-		return nil, errors.Errorf("%s", imageError)
+		return nil, errors.Wrapf(ErrNoSuchImage, imageError)
 
 	}
 
@@ -275,7 +275,7 @@ func (i *Image) getLocalImage() (*storage.Image, error) {
 		return repoImage, nil
 	}
 
-	return nil, errors.Wrapf(err, imageError)
+	return nil, errors.Wrapf(ErrNoSuchImage, err.Error())
 }
 
 // ID returns the image ID as a string