KNOX-3065: SSE support for Knox

gateway-spi/pom.xml

@@ -55,6 +55,24 @@
             <artifactId>gateway-util-urltemplate</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpasyncclient</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.apache.httpcomponents</groupId>
+                    <artifactId>httpcore</artifactId>
+                </exclusion>
+                <exclusion>
+                    <groupId>org.apache.httpcomponents</groupId>
+                    <artifactId>httpcore-nio</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpcore-nio</artifactId>
+        </dependency>
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>

gateway-spi/src/main/java/org/apache/knox/gateway/SpiGatewayMessages.java

@@ -123,4 +123,19 @@ public interface SpiGatewayMessages {
 
   @Message( level = MessageLevel.ERROR, text = "No valid principal found" )
   void noPrincipalFound();
+
+  @Message( level = MessageLevel.INFO, text = "Every event was read from the SSE stream" )
+  void sseConnectionDone();
+
+  @Message( level = MessageLevel.ERROR, text = "Error during SSE connection: {0}" )
+  void sseConnectionError(String error);
+
+  @Message( level = MessageLevel.ERROR, text = "Error writing into the SSE output stream : {0}" )
+  void errorWritingOutputStream(@StackTrace(level=MessageLevel.ERROR) Exception e);
+
+  @Message( level = MessageLevel.WARN, text = "SSE connection cancelled" )
+  void sseConnectionCancelled();
+
+  @Message( level = MessageLevel.ERROR, text = "Unable to close SSE producer" )
+  void sseProducerCloseError(@StackTrace(level=MessageLevel.ERROR) Exception e);
 }

gateway-spi/src/main/java/org/apache/knox/gateway/dispatch/DefaultHttpAsyncClientFactory.java

@@ -0,0 +1,87 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.knox.gateway.dispatch;
+
+import org.apache.http.auth.AuthSchemeProvider;
+import org.apache.http.auth.AuthScope;
+import org.apache.http.client.CredentialsProvider;
+import org.apache.http.client.config.AuthSchemes;
+import org.apache.http.config.Registry;
+import org.apache.http.config.RegistryBuilder;
+import org.apache.http.impl.DefaultConnectionReuseStrategy;
+import org.apache.http.impl.client.BasicCredentialsProvider;
+import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
+import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
+import org.apache.http.impl.nio.client.HttpAsyncClients;
+import org.apache.http.nio.client.HttpAsyncClient;
+import org.apache.knox.gateway.config.GatewayConfig;
+import org.apache.knox.gateway.services.GatewayServices;
+import org.apache.knox.gateway.services.ServiceType;
+import org.apache.knox.gateway.services.metrics.MetricsService;
+
+import javax.net.ssl.SSLContext;
+import javax.servlet.FilterConfig;
+
+public class DefaultHttpAsyncClientFactory extends DefaultHttpClientFactory implements HttpAsyncClientFactory {
+
+    @Override
+    public HttpAsyncClient createAsyncHttpClient(FilterConfig filterConfig) {
+        final String serviceRole = filterConfig.getInitParameter(PARAMETER_SERVICE_ROLE);
+        HttpAsyncClientBuilder builder;
+        GatewayConfig gatewayConfig = (GatewayConfig) filterConfig.getServletContext().getAttribute(GatewayConfig.GATEWAY_CONFIG_ATTRIBUTE);
+        GatewayServices services = (GatewayServices) filterConfig.getServletContext()
+                .getAttribute(GatewayServices.GATEWAY_SERVICES_ATTRIBUTE);
+        if (gatewayConfig != null && gatewayConfig.isMetricsEnabled()) {
+            MetricsService metricsService = services.getService(ServiceType.METRICS_SERVICE);
+            builder = metricsService.getInstrumented(HttpAsyncClientBuilder.class);
+        } else {
+            builder = HttpAsyncClients.custom();
+        }
+
+        // Conditionally set a custom SSLContext
+        SSLContext sslContext = createSSLContext(services, filterConfig, serviceRole);
+        if (sslContext != null) {
+            builder.setSSLContext(sslContext);
+        }
+
+        if (Boolean.parseBoolean(System.getProperty(GatewayConfig.HADOOP_KERBEROS_SECURED))) {
+            CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
+            credentialsProvider.setCredentials(AuthScope.ANY, new DefaultHttpAsyncClientFactory.UseJaasCredentials());
+
+            Registry<AuthSchemeProvider> authSchemeRegistry = RegistryBuilder.<AuthSchemeProvider>create()
+                    .register(AuthSchemes.SPNEGO, new KnoxSpnegoAuthSchemeFactory(true))
+                    .build();
+
+            builder.setDefaultAuthSchemeRegistry(authSchemeRegistry)
+                    .setDefaultCookieStore(new HadoopAuthCookieStore(gatewayConfig))
+                    .setDefaultCredentialsProvider(credentialsProvider);
+        } else {
+            builder.setDefaultCookieStore(new DefaultHttpAsyncClientFactory.NoCookieStore());
+        }
+
+        builder.setKeepAliveStrategy(DefaultConnectionKeepAliveStrategy.INSTANCE);
+        builder.setConnectionReuseStrategy(DefaultConnectionReuseStrategy.INSTANCE);
+        builder.setRedirectStrategy(new DefaultHttpAsyncClientFactory.NeverRedirectStrategy());
+        int maxConnections = getMaxConnections(filterConfig);
+        builder.setMaxConnTotal(maxConnections);
+        builder.setMaxConnPerRoute(maxConnections);
+        builder.setDefaultRequestConfig(getRequestConfig(filterConfig, serviceRole));
+
+        return builder.build();
+    }
+}

gateway-spi/src/main/java/org/apache/knox/gateway/dispatch/DefaultHttpClientFactory.java

@@ -69,7 +69,7 @@
 
 public class DefaultHttpClientFactory implements HttpClientFactory {
   private static final SpiGatewayMessages LOG = MessagesFactory.get(SpiGatewayMessages.class);
-  private static final String PARAMETER_SERVICE_ROLE = "serviceRole";
+  protected static final String PARAMETER_SERVICE_ROLE = "serviceRole";
   static final String PARAMETER_USE_TWO_WAY_SSL = "useTwoWaySsl";
   /* retry in case of NoHttpResponseException */
   static final String PARAMETER_RETRY_COUNT = "retryCount";
@@ -255,7 +255,7 @@ static RequestConfig getRequestConfig(FilterConfig config, String serviceRole) {
     return builder.build();
   }
 
-  private static class NoCookieStore implements CookieStore {
+  protected static class NoCookieStore implements CookieStore {
     @Override
     public void addCookie(Cookie cookie) {
       //no op
@@ -277,7 +277,7 @@ public void clear() {
     }
   }
 
-  private static class NeverRedirectStrategy implements RedirectStrategy {
+  protected static class NeverRedirectStrategy implements RedirectStrategy {
     @Override
     public boolean isRedirected( HttpRequest request, HttpResponse response, HttpContext context )
         throws ProtocolException {
@@ -298,7 +298,7 @@ public boolean retryRequest( IOException exception, int executionCount, HttpCont
     }
   }
 
-  private static class UseJaasCredentials implements Credentials {
+  protected static class UseJaasCredentials implements Credentials {
 
     @Override
     public String getPassword() {
@@ -312,7 +312,7 @@ public Principal getUserPrincipal() {
 
   }
 
-  private int getMaxConnections( FilterConfig filterConfig ) {
+  protected int getMaxConnections( FilterConfig filterConfig ) {
     int maxConnections = 32;
     GatewayConfig config =
         (GatewayConfig)filterConfig.getServletContext().getAttribute( GatewayConfig.GATEWAY_CONFIG_ATTRIBUTE );
@@ -330,7 +330,7 @@ private int getMaxConnections( FilterConfig filterConfig ) {
     return maxConnections;
   }
 
-  private static int getConnectionTimeout( FilterConfig filterConfig ) {
+  protected static int getConnectionTimeout( FilterConfig filterConfig ) {
     int timeout = -1;
     GatewayConfig globalConfig =
         (GatewayConfig)filterConfig.getServletContext().getAttribute( GatewayConfig.GATEWAY_CONFIG_ATTRIBUTE );
@@ -348,7 +348,7 @@ private static int getConnectionTimeout( FilterConfig filterConfig ) {
     return timeout;
   }
 
-  private static int getSocketTimeout( FilterConfig filterConfig ) {
+  protected static int getSocketTimeout( FilterConfig filterConfig ) {
     int timeout = -1;
     GatewayConfig globalConfig =
         (GatewayConfig)filterConfig.getServletContext().getAttribute( GatewayConfig.GATEWAY_CONFIG_ATTRIBUTE );
@@ -366,7 +366,7 @@ private static int getSocketTimeout( FilterConfig filterConfig ) {
     return timeout;
   }
 
-  private static long parseTimeout( String s ) {
+  protected static long parseTimeout( String s ) {
     PeriodFormatter f = new PeriodFormatterBuilder()
         .appendMinutes().appendSuffix("m"," min")
         .appendSeconds().appendSuffix("s"," sec")
@@ -375,7 +375,7 @@ private static long parseTimeout( String s ) {
     return p.toStandardDuration().getMillis();
   }
 
-  private static String getCookieSpec(FilterConfig filterConfig) {
+  protected static String getCookieSpec(FilterConfig filterConfig) {
     String cookieSpec = filterConfig.getInitParameter("httpclient.cookieSpec");
     if (StringUtils.isNotBlank(cookieSpec)) {
       return cookieSpec;

gateway-spi/src/main/java/org/apache/knox/gateway/dispatch/GatewayDispatchFilter.java

@@ -32,6 +32,7 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
+import java.lang.reflect.Constructor;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.util.Collections;
@@ -71,13 +72,13 @@ public void init(FilterConfig filterConfig) throws ServletException {
     synchronized(lock) {
       if (dispatch == null) {
         String dispatchImpl = filterConfig.getInitParameter("dispatch-impl");
-        dispatch = newInstanceFromName(dispatchImpl);
+        dispatch = newInstanceFromName(dispatchImpl, filterConfig);
       }
       ConfigurationInjectorBuilder.configuration().target(dispatch).source(filterConfig).inject();
       HttpClientFactory httpClientFactory;
       String httpClientFactoryClass = filterConfig.getInitParameter("httpClientFactory");
       if (httpClientFactoryClass != null) {
-        httpClientFactory = newInstanceFromName(httpClientFactoryClass);
+        httpClientFactory = newInstanceFromName(httpClientFactoryClass, filterConfig);
       } else {
         httpClientFactory = new DefaultHttpClientFactory();
       }
@@ -217,15 +218,28 @@ public void doMethod(Dispatch dispatch, HttpServletRequest request, HttpServletR
     }
   }
 
-  private <T> T newInstanceFromName(String dispatchImpl) throws ServletException {
+  private <T> T newInstanceFromName(String dispatchImpl, FilterConfig filterConfig) throws ServletException {
     try {
       Class<T> clazz = loadClass(dispatchImpl);
+      Constructor<?> constructor = this.getConstructorWithType(clazz, FilterConfig.class);
+      if(constructor != null) {
+        return (T) constructor.newInstance(filterConfig);
+      }
       return clazz.newInstance();
     } catch ( Exception e ) {
       throw new ServletException(e);
     }
   }
 
+  private <T> Constructor<?> getConstructorWithType(Class<T> clazz, Class<?> type) {
+    for (Constructor<?> constructor : clazz.getConstructors()) {
+      if (constructor.getParameterCount() == 1 && constructor.getParameterTypes()[0] == type) {
+        return constructor;
+      }
+    }
+    return null;
+  }
+
   private <T> Class<T> loadClass(String className) throws ClassNotFoundException {
       ClassLoader loader = Thread.currentThread().getContextClassLoader();
       if ( loader == null ) {

gateway-spi/src/main/java/org/apache/knox/gateway/dispatch/HttpAsyncClientFactory.java

@@ -0,0 +1,26 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.knox.gateway.dispatch;
+
+import org.apache.http.nio.client.HttpAsyncClient;
+
+import javax.servlet.FilterConfig;
+
+public interface HttpAsyncClientFactory extends HttpClientFactory {
+    HttpAsyncClient createAsyncHttpClient(FilterConfig filterConfig);
+}