com.github.enadim.spring.cloud.ribbon.predicate.DynamicMatcher Maven / Gradle / Ivy
/*
* 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 java.util.Map;
import static com.github.enadim.spring.cloud.ribbon.context.ExecutionContextHolder.current;
/**
* Filters Servers that does not have the desired metadata entry.
* The metadata key is fetched from the context entry with the desired key {@link #dynamicEntryKey}
*
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 DynamicMatcher extends DiscoveryEnabledServerPredicate {
/**
* the dynamic entry key. used to get the metadata key to match.
*/
private final String dynamicEntryKey;
/**
* Sole constructor.
*
* @param dynamicEntryKey the dynamic metadata key.
*/
public DynamicMatcher(String dynamicEntryKey) {
this.dynamicEntryKey = dynamicEntryKey;
}
/**
* {@inheritDoc}
*/
@Override
protected boolean doApply(DiscoveryEnabledServer server) {
String metadataKey = current().get(dynamicEntryKey);
Map 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(),
metadata,
accept);
return accept;
} else {
log.trace("[{}] not defined! : {}{} => false",
dynamicEntryKey,
server.getHostPort(),
metadata);
return false;
}
}
}