container-commit: support --squash to squash layers into one

Allow users to commit containers into a single layer.

Usage
```bash
podman container commit --squash <name>
```

Signed-off-by: Aditya R <arajan@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/test/e2e/commit_test.go b/test/e2e/commit_test.go
index 495e31520..6bcf17bfe 100644
--- a/test/e2e/commit_test.go
+++ b/test/e2e/commit_test.go
@@ -4,6 +4,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 
 	. "github.com/containers/podman/v4/test/utils"
 	. "github.com/onsi/ginkgo"
@@ -133,6 +134,23 @@ var _ = Describe("Podman commit", func() {
 		Expect(foundBlue).To(Equal(true))
 	})
 
+	It("podman commit container with --squash", func() {
+		test := podmanTest.Podman([]string{"run", "--name", "test1", "-d", ALPINE, "ls"})
+		test.WaitWithDefaultTimeout()
+		Expect(test).Should(Exit(0))
+		Expect(podmanTest.NumberOfContainers()).To(Equal(1))
+
+		session := podmanTest.Podman([]string{"commit", "--squash", "test1", "foobar.com/test1-image:latest"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+
+		session = podmanTest.Podman([]string{"inspect", "--format", "{{.RootFS.Layers}}", "foobar.com/test1-image:latest"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(0))
+		// Check for one layers
+		Expect(strings.Fields(session.OutputToString())).To(HaveLen(1))
+	})
+
 	It("podman commit container with change flag and JSON entrypoint with =", func() {
 		test := podmanTest.Podman([]string{"run", "--name", "test1", "-d", ALPINE, "ls"})
 		test.WaitWithDefaultTimeout()