disable schema1 by default, add a config flag to enable it

port of #2473

Signed-off-by: Viktor Stanchev <me@viktorstanchev.com>

registry/handlers/api_test.go

@@ -2027,6 +2027,7 @@ func newTestEnvMirror(t *testing.T, deleteEnabled bool) *testEnv {
 			RemoteURL: "http://example.com",
 		},
 	}
+	config.Compatibility.Schema1.Enabled = true
 
 	return newTestEnvWithConfig(t, &config)
 
@@ -2043,6 +2044,7 @@ func newTestEnv(t *testing.T, deleteEnabled bool) *testEnv {
 		},
 	}
 
+	config.Compatibility.Schema1.Enabled = true
 	config.HTTP.Headers = headerConfig
 
 	return newTestEnvWithConfig(t, &config)
@@ -2565,6 +2567,7 @@ func TestProxyManifestGetByTag(t *testing.T) {
 			}},
 		},
 	}
+	truthConfig.Compatibility.Schema1.Enabled = true
 	truthConfig.HTTP.Headers = headerConfig
 
 	imageName, _ := reference.WithName("foo/bar")
@@ -2583,6 +2586,7 @@ func TestProxyManifestGetByTag(t *testing.T) {
 			RemoteURL: truthEnv.server.URL,
 		},
 	}
+	proxyConfig.Compatibility.Schema1.Enabled = true
 	proxyConfig.HTTP.Headers = headerConfig
 
 	proxyEnv := newTestEnvWithConfig(t, &proxyConfig)

registry/handlers/app.go

@@ -174,6 +174,10 @@ func NewApp(ctx context.Context, config *configuration.Configuration) *App {
 
 	options = append(options, storage.Schema1SigningKey(app.trustKey))
 
+	if config.Compatibility.Schema1.Enabled {
+		options = append(options, storage.EnableSchema1)
+	}
+
 	if config.HTTP.Host != "" {
 		u, err := url.Parse(config.HTTP.Host)
 		if err != nil {