Use canonical platform values. Fix 1995. (#2025)

* Use canonical image architectures. Closes #1995.

Prior to this change, Kaniko was not using the platform's canonical value.

* Update platform unit test.

Author: gadiego92

cmd/executor/cmd/root.go

@@ -224,7 +224,7 @@ func addKanikoOptionsFlags() {
 
 	// Default the custom platform flag to our current platform, and validate it.
 	if opts.CustomPlatform == "" {
-		opts.CustomPlatform = platforms.DefaultString()
+		opts.CustomPlatform = platforms.Format(platforms.Normalize(platforms.DefaultSpec()))
 	}
 	if _, err := v1.ParsePlatform(opts.CustomPlatform); err != nil {
 		logrus.Fatalf("Invalid platform %q: %v", opts.CustomPlatform, err)

cmd/warmer/cmd/root.go

@@ -90,7 +90,7 @@ func addKanikoOptionsFlags() {
 
 	// Default the custom platform flag to our current platform, and validate it.
 	if opts.CustomPlatform == "" {
-		opts.CustomPlatform = platforms.DefaultString()
+		opts.CustomPlatform = platforms.Format(platforms.Normalize(platforms.DefaultSpec()))
 	}
 	if _, err := v1.ParsePlatform(opts.CustomPlatform); err != nil {
 		logrus.Fatalf("Invalid platform %q: %v", opts.CustomPlatform, err)

pkg/executor/build_test.go

@@ -372,7 +372,7 @@ COPY --from=second /bar /bat
 			ioutil.WriteFile(f.Name(), []byte(tt.args.dockerfile), 0755)
 			opts := &config.KanikoOptions{
 				DockerfilePath: f.Name(),
-				CustomPlatform: platforms.DefaultString(),
+				CustomPlatform: platforms.Format(platforms.Normalize(platforms.DefaultSpec())),
 			}
 			testStages, metaArgs, err := dockerfile.ParseStages(opts)
 			if err != nil {