Add imageParts.referenceWithRegistry

This is the primary goal of decompose()+assemble(), to support
qualifying an image name.

Does not have any users yet, so does not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

libpod/image/parts.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/containers/image/docker/reference"
+	"github.com/pkg/errors"
 )
 
 // imageParts describes the parts of an image's name
@@ -76,6 +77,23 @@ func decompose(input string) (imageParts, error) {
 	}, nil
 }
 
+// referenceWithRegistry returns a (normalized) reference.Named composed of ip (with !ip.hasRegistry)
+// qualified with registry.
+func (ip *imageParts) referenceWithRegistry(registry string) (reference.Named, error) {
+	if ip.hasRegistry {
+		return nil, errors.Errorf("internal error: referenceWithRegistry called on imageParts with a registry (%#v)", *ip)
+	}
+	// We could build a reference.WithName+WithTag/WithDigest here, but we need to round-trip via a string
+	// and a ParseNormalizedNamed anyway to get the right normalization of docker.io/library, so
+	// just use a string directly.
+	qualified := registry + "/" + ip.unnormalizedRef.String()
+	ref, err := reference.ParseNormalizedNamed(qualified)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error normalizing registry+unqualified reference %#v", qualified)
+	}
+	return ref, nil
+}
+
 // assemble concatenates an image's parts into a string
 func (ip *imageParts) assemble() string {
 	spec := fmt.Sprintf("%s:%s", ip.name, ip.tag)

libpod/image/parts_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestDecompose(t *testing.T) {
@@ -62,3 +63,44 @@ func TestDecompose(t *testing.T) {
 		}
 	}
 }
+
+func TestImagePartsReferenceWithRegistry(t *testing.T) {
+	const digestSuffix = "@sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+
+	for _, c := range []struct {
+		input                     string
+		withDocker, withNonDocker string
+	}{
+		{"example.com/ns/busybox", "", ""},                                                                            // Fully-qualified input is invalid.
+		{"busybox", "docker.io/library/busybox", "example.com/busybox"},                                               // Single-name input
+		{"ns/busybox", "docker.io/ns/busybox", "example.com/ns/busybox"},                                              // Namespaced input
+		{"ns/busybox:notlatest", "docker.io/ns/busybox:notlatest", "example.com/ns/busybox:notlatest"},                // name:tag
+		{"ns/busybox" + digestSuffix, "docker.io/ns/busybox" + digestSuffix, "example.com/ns/busybox" + digestSuffix}, // name@digest
+		{ // name:tag@digest
+			"ns/busybox:notlatest" + digestSuffix,
+			"docker.io/ns/busybox:notlatest" + digestSuffix, "example.com/ns/busybox:notlatest" + digestSuffix,
+		},
+	} {
+		parts, err := decompose(c.input)
+		require.NoError(t, err)
+		if c.withDocker == "" {
+			_, err := parts.referenceWithRegistry("docker.io")
+			assert.Error(t, err, c.input)
+			_, err = parts.referenceWithRegistry("example.com")
+			assert.Error(t, err, c.input)
+		} else {
+			ref, err := parts.referenceWithRegistry("docker.io")
+			require.NoError(t, err, c.input)
+			assert.Equal(t, c.withDocker, ref.String())
+			ref, err = parts.referenceWithRegistry("example.com")
+			require.NoError(t, err, c.input)
+			assert.Equal(t, c.withNonDocker, ref.String())
+		}
+	}
+
+	// Invalid registry value
+	parts, err := decompose("busybox")
+	require.NoError(t, err)
+	_, err = parts.referenceWithRegistry("invalid@domain")
+	assert.Error(t, err)
+}