/* * 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.flink.runtime.rest.handler; import org.apache.flink.api.common.time.Time; import org.apache.flink.runtime.rest.handler.router.RoutedRequest; import org.apache.flink.runtime.rest.handler.util.HandlerUtils; import org.apache.flink.runtime.rest.messages.ErrorResponseBody; import org.apache.flink.runtime.webmonitor.RestfulGateway; import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever; import org.apache.flink.util.OptionalConsumer; import org.apache.flink.util.Preconditions; import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandler; import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandlerContext; import org.apache.flink.shaded.netty4.io.netty.channel.SimpleChannelInboundHandler; import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpRequest; import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.annotation.Nonnull; import java.util.Map; /** * {@link SimpleChannelInboundHandler} which encapsulates the leader retrieval logic for the * REST endpoints. * * @param <T> type of the leader to retrieve */ @ChannelHandler.Sharable public abstract class LeaderRetrievalHandler<T extends RestfulGateway> extends SimpleChannelInboundHandler<RoutedRequest> { protected final Logger logger = LoggerFactory.getLogger(getClass()); protected final GatewayRetriever<? extends T> leaderRetriever; protected final Time timeout; protected final Map<String, String> responseHeaders; protected LeaderRetrievalHandler( @Nonnull GatewayRetriever<? extends T> leaderRetriever, @Nonnull Time timeout, @Nonnull Map<String, String> responseHeaders) { this.leaderRetriever = Preconditions.checkNotNull(leaderRetriever); this.timeout = Preconditions.checkNotNull(timeout); this.responseHeaders = Preconditions.checkNotNull(responseHeaders); } @Override protected void channelRead0( ChannelHandlerContext channelHandlerContext, RoutedRequest routedRequest) { HttpRequest request = routedRequest.getRequest(); OptionalConsumer<? extends T> optLeaderConsumer = OptionalConsumer.of(leaderRetriever.getNow()); optLeaderConsumer.ifPresent( gateway -> { try { respondAsLeader(channelHandlerContext, routedRequest, gateway); } catch (Exception e) { logger.error("Error while responding to the http request.", e); HandlerUtils.sendErrorResponse( channelHandlerContext, request, new ErrorResponseBody("Error while responding to the http request."), HttpResponseStatus.INTERNAL_SERVER_ERROR, responseHeaders); } } ).ifNotPresent( () -> HandlerUtils.sendErrorResponse( channelHandlerContext, request, new ErrorResponseBody("Service temporarily unavailable due to an ongoing leader election. Please refresh."), HttpResponseStatus.SERVICE_UNAVAILABLE, responseHeaders)); } protected abstract void respondAsLeader(ChannelHandlerContext channelHandlerContext, RoutedRequest request, T gateway) throws Exception; }