Print header for 'podman images' even with no images

Fixes #2877

Signed-off-by: Matthew Heon <mheon@redhat.com>

cmd/podman/images.go

@@ -318,13 +318,14 @@ func getImagesJSONOutput(ctx context.Context, images []*adapter.ContainerImage)
 
 func generateImagesOutput(ctx context.Context, images []*adapter.ContainerImage, opts imagesOptions) error {
 	templateMap := GenImageOutputMap()
-	if len(images) == 0 {
-		return nil
-	}
 	var out formats.Writer
 
 	switch opts.format {
 	case formats.JSONString:
+		// If 0 images are present, print nothing for JSON
+		if len(images) == 0 {
+			return nil
+		}
 		imagesOutput := getImagesJSONOutput(ctx, images)
 		out = formats.JSONStructArray{Output: imagesToGeneric([]imagesTemplateParams{}, imagesOutput)}
 	default:

test/e2e/images_test.go

@@ -43,6 +43,17 @@ var _ = Describe("Podman images", func() {
 		Expect(session.LineInOuputStartsWith("docker.io/library/busybox")).To(BeTrue())
 	})
 
+	It("podman images with no images prints header", func() {
+		rmi := podmanTest.Podman([]string{"rmi", "-a"})
+		rmi.WaitWithDefaultTimeout()
+		Expect(rmi.ExitCode()).To(Equal(0))
+
+		session := podmanTest.Podman([]string{"images"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+		Expect(len(session.OutputToStringArray())).To(Equal(1))
+	})
+
 	It("podman image List", func() {
 		session := podmanTest.Podman([]string{"image", "list"})
 		session.WaitWithDefaultTimeout()

test/e2e/prune_test.go

@@ -82,7 +82,7 @@ var _ = Describe("Podman rm", func() {
 		prune.WaitWithDefaultTimeout()
 		Expect(prune.ExitCode()).To(Equal(0))
 
-		images := podmanTest.Podman([]string{"images", "-a"})
+		images := podmanTest.Podman([]string{"images", "-aq"})
 		images.WaitWithDefaultTimeout()
 		// all images are unused, so they all should be deleted!
 		Expect(len(images.OutputToStringArray())).To(Equal(0))
@@ -95,7 +95,7 @@ var _ = Describe("Podman rm", func() {
 		prune.WaitWithDefaultTimeout()
 		Expect(prune.ExitCode()).To(Equal(0))
 
-		images := podmanTest.Podman([]string{"images", "-a"})
+		images := podmanTest.Podman([]string{"images", "-aq"})
 		images.WaitWithDefaultTimeout()
 		// all images are unused, so they all should be deleted!
 		Expect(len(images.OutputToStringArray())).To(Equal(0))

test/e2e/rmi_test.go

@@ -270,7 +270,7 @@ RUN find $LOCAL
 		fmt.Println(session.OutputToString())
 		Expect(session.ExitCode()).To(Equal(0))
 
-		images := podmanTest.Podman([]string{"images", "--all"})
+		images := podmanTest.Podman([]string{"images", "-aq"})
 		images.WaitWithDefaultTimeout()
 		Expect(images.ExitCode()).To(Equal(0))
 		Expect(len(images.OutputToStringArray())).To(Equal(0))