Fix #1740: Handle OPTIONS in management API

frontend/server/src/main/java/org/pytorch/serve/http/api/rest/ManagementRequestHandler.java

@@ -29,6 +29,7 @@
 import org.pytorch.serve.http.messages.ListModelsResponse;
 import org.pytorch.serve.http.messages.RegisterModelRequest;
 import org.pytorch.serve.job.RestJob;
+import org.pytorch.serve.openapi.OpenApiUtils;
 import org.pytorch.serve.servingsdk.ModelServerEndpoint;
 import org.pytorch.serve.util.ApiUtils;
 import org.pytorch.serve.util.JsonUtils;
@@ -92,6 +93,15 @@ public void handleRequest(
                     }
                 } else if (HttpMethod.DELETE.equals(method)) {
                     handleUnregisterModel(ctx, segments[2], modelVersion);
+                } else if (HttpMethod.OPTIONS.equals(method)) {
+                    ModelManager modelManager = ModelManager.getInstance();
+                    Model model = modelManager.getModel(segments[2], modelVersion);
+                    if (model == null) {
+                        throw new ModelNotFoundException("Model not found: " + segments[2]);
+                    }
+
+                    String resp = OpenApiUtils.getModelManagementApi(model);
+                    NettyUtils.sendJsonResponse(ctx, resp);
                 } else {
                     throw new MethodNotAllowedException();
                 }

frontend/server/src/main/java/org/pytorch/serve/openapi/OpenApiUtils.java

@@ -71,6 +71,22 @@ public static String getModelApi(Model model) {
         return JsonUtils.GSON_PRETTY.toJson(openApi);
     }
 
+    public static String getModelManagementApi(Model model) {
+        String modelName = model.getModelName();
+        OpenApi openApi = new OpenApi();
+        Info info = new Info();
+        info.setTitle("RESTful Management API for: " + modelName);
+        ConfigManager config = ConfigManager.getInstance();
+        info.setVersion(config.getProperty("version", null));
+        openApi.setInfo(info);
+
+        openApi.addPath("/models/{model_name}", getModelManagerPath(false));
+        openApi.addPath("/models/{model_name}/{model_version}", getModelManagerPath(true));
+        openApi.addPath("/models/{model_name}/{model_version}/set-default", getSetDefaultPath());
+
+        return JsonUtils.GSON_PRETTY.toJson(openApi);
+    }
+
     private static Path getApiDescriptionPath(String operationID, boolean legacy) {
         Schema schema = new Schema("object");
         schema.addProperty("openapi", new Schema("string"), true);

frontend/server/src/test/java/org/pytorch/serve/ModelServerTest.java

@@ -63,6 +63,7 @@ public class ModelServerTest {
     private String listManagementApisResult;
     private String listMetricsApisResult;
     private String noopApiResult;
+    private String noopManagementApiResult;
 
     static {
         TestUtils.init();
@@ -99,6 +100,11 @@ public void beforeSuite()
         try (InputStream is = new FileInputStream("src/test/resources/describe_api.json")) {
             noopApiResult = IOUtils.toString(is, StandardCharsets.UTF_8.name());
         }
+
+        try (InputStream is = new FileInputStream("src/test/resources/model_management_api.json")) {
+            noopManagementApiResult =
+                    String.format(IOUtils.toString(is, StandardCharsets.UTF_8.name()), version);
+        }
     }
 
     @AfterClass
@@ -193,6 +199,21 @@ public void testDescribeApi() throws InterruptedException {
     @Test(
             alwaysRun = true,
             dependsOnMethods = {"testDescribeApi"})
+    public void testModelManagementApi() throws InterruptedException {
+        Channel channel = TestUtils.getManagementChannel(configManager);
+        TestUtils.setResult(null);
+        TestUtils.setLatch(new CountDownLatch(1));
+        TestUtils.describeModelManagementApi(channel, "noop");
+        TestUtils.getLatch().await();
+
+        Assert.assertEquals(
+                TestUtils.getResult().replaceAll("(\\\\r|\r\n|\n|\n\r)", "\r"),
+                noopManagementApiResult.replaceAll("(\\\\r|\r\n|\n|\n\r)", "\r"));
+    }
+
+    @Test(
+            alwaysRun = true,
+            dependsOnMethods = {"testModelManagementApi"})
     public void testInitialWorkers() throws InterruptedException {
         Channel channel = TestUtils.getManagementChannel(configManager);
         TestUtils.setResult(null);

frontend/server/src/test/java/org/pytorch/serve/TestUtils.java

@@ -57,10 +57,13 @@ public final class TestUtils {
     private TestUtils() {}
 
     public static void init() {
+        System.out.println("init");
         // set up system properties for local IDE debug
+        System.out.println("tsConfigFile1: " + System.getProperty("tsConfigFile"));
         if (System.getProperty("tsConfigFile") == null) {
             System.setProperty("tsConfigFile", "src/test/resources/config.properties");
         }
+        System.out.println("tsConfigFile2: " + System.getProperty("tsConfigFile"));
         if (System.getProperty("METRICS_LOCATION") == null) {
             System.setProperty("METRICS_LOCATION", "build/logs");
         }
@@ -260,6 +263,13 @@ public static void describeModelApi(Channel channel, String modelName) {
         channel.writeAndFlush(req);
     }
 
+    public static void describeModelManagementApi(Channel channel, String modelName) {
+        HttpRequest req =
+                new DefaultFullHttpRequest(
+                        HttpVersion.HTTP_1_1, HttpMethod.OPTIONS, "/models/" + modelName);
+        channel.writeAndFlush(req);
+    }
+
     public static void describeModel(
             Channel channel, String modelName, String version, boolean customized) {
         String requestURL = "/models/" + modelName;