/* * Copyright (c) 2017 the original author or authors * * Licensed 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 com.github.enadim.spring.cloud.ribbon.predicate; import com.netflix.niws.loadbalancer.DiscoveryEnabledServer; import lombok.extern.slf4j.Slf4j; import javax.validation.constraints.NotNull; import java.util.Map; import static com.github.enadim.spring.cloud.ribbon.context.ExecutionContextHolder.current; import static java.lang.String.format; /** * Filters Servers that does have the desired metadata entry. * <p>The metadata key is fetched from the context entry with the desired key {@link #dynamicEntryKey} * <p>Concrete use case with a µservice that share a point to point connection with external system (this connection is established only once): market access / FIX connection. * This µservice should add the connection up marker to its metadata so that the clients can target the instance holding the connection. * * @author Nadim Benabdenbi */ @Slf4j public class DynamicMetadataMatcher extends DiscoveryEnabledServerPredicate { /** * the dynamic entry key. used to get the metadata key to match. */ private final String dynamicEntryKey; /** * matches result when dynamic entry key is missing. */ private final boolean matchIfMissing; /** * Sole constructor. * * @param dynamicEntryKey the dynamic metadata key. * @param matchIfMissing the result when dynamic entry key is not defined */ public DynamicMetadataMatcher(@NotNull String dynamicEntryKey, boolean matchIfMissing) { this.dynamicEntryKey = dynamicEntryKey; this.matchIfMissing = matchIfMissing; } /** * {@inheritDoc} */ @Override protected boolean doApply(DiscoveryEnabledServer server) { String metadataKey = current().get(dynamicEntryKey); Map<String, String> metadata = server.getInstanceInfo().getMetadata(); if (metadataKey != null) { String expected = current().get(metadataKey); String actual = metadata.get(metadataKey); boolean accept = (expected == null && actual == null) || (expected != null && expected.equals(actual)); log.trace("Expected [{}={}] vs {}:{}{} => {}", metadataKey, expected, server.getHostPort(), server.getMetaInfo().getAppName(), metadata, accept); return accept; } else { log.trace("[{}] not defined! : {}{} => %b", dynamicEntryKey, server.getHostPort(), metadata, matchIfMissing); return matchIfMissing; } } /** * {@inheritDoc} */ @Override public String toString() { String metadataKey = current().get(dynamicEntryKey); return format("DynamicMetadataMatcher[(%s=%s)=%s,matchIfMissing=%b]", dynamicEntryKey, metadataKey, metadataKey == null ? null : current().get(metadataKey), matchIfMissing); } }