fix: allow HTTPS for localhost

cmd/oras/internal/option/remote.go

@@ -43,7 +43,6 @@ import (
 // Remote options struct.
 type Remote struct {
 	CACertFilePath    string
-	PlainHTTP         bool
 	Insecure          bool
 	Configs           []string
 	Username          string
@@ -56,6 +55,7 @@ type Remote struct {
 	headerFlags           []string
 	headers               http.Header
 	warned                map[string]*sync.Map
+	plainHTTP             func() (plainHTTP bool, enforced bool)
 }
 
 // EnableDistributionSpecFlag set distribution specification flag as applicable.
@@ -98,7 +98,11 @@ func (opts *Remote) ApplyFlagsWithPrefix(fs *pflag.FlagSet, prefix, description
 	fs.StringVarP(&opts.Username, flagPrefix+"username", shortUser, "", notePrefix+"registry username")
 	fs.StringVarP(&opts.Password, flagPrefix+"password", shortPassword, "", notePrefix+"registry password or identity token")
 	fs.BoolVarP(&opts.Insecure, flagPrefix+"insecure", "", false, "allow connections to "+notePrefix+"SSL registry without certs")
-	fs.BoolVarP(&opts.PlainHTTP, flagPrefix+"plain-http", "", false, "allow insecure connections to "+notePrefix+"registry without SSL check")
+	plainHTTPFlagName := flagPrefix + "plain-http"
+	plainHTTP := fs.Bool(plainHTTPFlagName, false, "allow insecure connections to "+notePrefix+"registry without SSL check")
+	opts.plainHTTP = func() (bool, bool) {
+		return *plainHTTP, fs.Changed(plainHTTPFlagName)
+	}
 	fs.StringVarP(&opts.CACertFilePath, flagPrefix+"ca-file", "", "", "server certificate authority file for the remote "+notePrefix+"registry")
 	fs.StringArrayVarP(&opts.resolveFlag, flagPrefix+"resolve", "", nil, "customized DNS for "+notePrefix+"registry, formatted in `host:port:address[:address_port]`")
 	fs.StringArrayVarP(&opts.Configs, flagPrefix+"registry-config", "", nil, "`path` of the authentication file for "+notePrefix+"registry")
@@ -305,9 +309,14 @@ func (opts *Remote) NewRepository(reference string, common Common, logger logrus
 
 // isPlainHttp returns the plain http flag for a given registry.
 func (opts *Remote) isPlainHttp(registry string) bool {
+	plainHTTP, enforced := opts.plainHTTP()
+	if enforced {
+		return plainHTTP
+	}
 	host, _, _ := net.SplitHostPort(registry)
 	if host == "localhost" || registry == "localhost" {
+		// not specified, defaults to plain http for localhost
 		return true
 	}
-	return opts.PlainHTTP
+	return plainHTTP
 }

cmd/oras/internal/option/remote_test.go

@@ -162,6 +162,16 @@ func TestRemote_authClient_resolve(t *testing.T) {
 	}
 }
 
+func plainHTTPEnabled() (plainHTTP bool, fromFlag bool) {
+	return true, true
+}
+func HTTPSEnabled() (plainHTTP bool, fromFlag bool) {
+	return false, true
+}
+func plainHTTPNotSpecified() (plainHTTP bool, fromFlag bool) {
+	return false, false
+}
+
 func TestRemote_NewRegistry(t *testing.T) {
 	caPath := filepath.Join(t.TempDir(), "oras-test.pem")
 	if err := os.WriteFile(caPath, pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: ts.Certificate().Raw}), 0644); err != nil {
@@ -174,6 +184,7 @@ func TestRemote_NewRegistry(t *testing.T) {
 	}{
 		Remote{
 			CACertFilePath: caPath,
+			plainHTTP:      plainHTTPNotSpecified,
 		},
 		Common{},
 	}
@@ -201,6 +212,7 @@ func TestRemote_NewRepository(t *testing.T) {
 	}{
 		Remote{
 			CACertFilePath: caPath,
+			plainHTTP:      plainHTTPNotSpecified,
 		},
 		Common{},
 	}
@@ -248,6 +260,7 @@ func TestRemote_NewRepository_Retry(t *testing.T) {
 	}{
 		Remote{
 			CACertFilePath: caPath,
+			plainHTTP:      plainHTTPNotSpecified,
 		},
 		Common{},
 	}
@@ -276,8 +289,8 @@ func TestRemote_NewRepository_Retry(t *testing.T) {
 	}
 }
 
-func TestRemote_isPlainHttp_localhost(t *testing.T) {
-	opts := Remote{PlainHTTP: false}
+func TestRemote_default_localhost(t *testing.T) {
+	opts := Remote{plainHTTP: plainHTTPNotSpecified}
 	got := opts.isPlainHttp("localhost")
 	if got != true {
 		t.Fatalf("tls should be disabled when domain is localhost")
@@ -291,6 +304,36 @@ func TestRemote_isPlainHttp_localhost(t *testing.T) {
 	}
 }
 
+func TestRemote_isPlainHTTP_localhost(t *testing.T) {
+	opts := Remote{plainHTTP: plainHTTPEnabled}
+	isplainHTTP := opts.isPlainHttp("localhost")
+	if isplainHTTP != true {
+		t.Fatalf("tls should be disabled when domain is localhost and --plain-http is used")
+
+	}
+
+	isplainHTTP = opts.isPlainHttp("localhost:9090")
+	if isplainHTTP != true {
+		t.Fatalf("tls should be disabled when domain is localhost and --plain-http is used")
+
+	}
+}
+
+func TestRemote_isHTTPS_localhost(t *testing.T) {
+	opts := Remote{plainHTTP: HTTPSEnabled}
+	got := opts.isPlainHttp("localhost")
+	if got != false {
+		t.Fatalf("tls should be enabled when domain is localhost and --plain-http=false is used")
+
+	}
+
+	got = opts.isPlainHttp("localhost:9090")
+	if got != false {
+		t.Fatalf("tls should be enabled when domain is localhost and --plain-http=false is used")
+
+	}
+}
+
 func TestRemote_parseResolve_err(t *testing.T) {
 	tests := []struct {
 		name string