Fix image build failed for GAR (#20596)

Author: iQQBot

components/image-builder-bob/pkg/proxy/proxy.go

@@ -60,7 +60,7 @@ func rewriteDockerAPIURL(u *url.URL, fromRepo, toRepo, host, tag string) {
 		from = "/v2/" + strings.Trim(fromRepo, "/") + "/"
 		to   = "/v2/" + strings.Trim(toRepo, "/") + "/"
 	)
-	u.Path = to + strings.TrimPrefix(u.Path, from)
+	u.Path = to + strings.TrimPrefix(strings.TrimPrefix(u.Path, from), "/")
 
 	// we reset the escaped encoding hint, because EscapedPath will produce a valid encoding.
 	u.RawPath = ""
@@ -95,7 +95,7 @@ func rewriteNonDockerAPIURL(u *url.URL, fromPrefix, toPrefix, host string) {
 	if toPrefix == "" {
 		to = "/"
 	}
-	u.Path = to + strings.TrimPrefix(u.Path, from)
+	u.Path = to + strings.TrimPrefix(strings.TrimPrefix(u.Path, from), "/")
 
 	// we reset the escaped encoding hint, because EscapedPath will produce a valid encoding.
 	u.RawPath = ""

components/image-builder-bob/pkg/proxy/proxy_test.go

@@ -69,6 +69,22 @@ func TestRewriteNonDockerAPIURL(t *testing.T) {
 				Path: "/to/some/random/path",
 			},
 		},
+		{
+			Name: "fromPrefix and toPrefix are not empty and origin url is not start with fromPrefix",
+			in: input{
+				fromPrefix: "from",
+				toPrefix:   "to",
+				host:       "localhost.com",
+				u: url.URL{
+					Host: "example.com",
+					Path: "/other-string/some/random/path",
+				},
+			},
+			u: url.URL{
+				Host: "localhost.com",
+				Path: "/to/other-string/some/random/path",
+			},
+		},
 		{
 			Name: "fromPrefix and toPrefix are empty",
 			in: input{
@@ -134,6 +150,23 @@ func TestRewriteDockerAPIURL(t *testing.T) {
 				Path: "/v2/base/some/random/path",
 			},
 		},
+		{
+			Name: "remote to localhost without repo",
+			in: input{
+				fromRepo: "base-images",
+				toRepo:   "base",
+				host:     "localhost.com",
+				tag:      "",
+				u: url.URL{
+					Host: "prince.azurecr.io",
+					Path: "/v2/other-string/some/random/path",
+				},
+			},
+			u: url.URL{
+				Host: "localhost.com",
+				Path: "/v2/base/v2/other-string/some/random/path",
+			},
+		},
 		{
 			Name: "localhost to remote",
 			in: input{