com.github.enadim.spring.cloud.ribbon.predicate.DynamicAttributeMatcher 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.api.RibbonRuleContextHolder.current;
/**
* Filters Servers that does not have the desired attribute key with the desired value.
* The attribute key is fetched from the context attribute having the key {@link #dynamicAttributeKey}
*
Concrete use case with a micro-service that share a point to point connection with external system (this connection is established only once): market access / FIX connection.
* The micro-service will add the connection marker to its metadata
*
* @author Nadim Benabdenbi
*/
@Slf4j
public class DynamicAttributeMatcher extends DiscoveryEnabledServerPredicate {
/**
* the dynamic attribute key. used to get the attribute key to match.
*/
private final String dynamicAttributeKey;
/**
* Sole constructor.
*
* @param dynamicAttributeKey the dynamic attribute key.
*/
public DynamicAttributeMatcher(String dynamicAttributeKey) {
this.dynamicAttributeKey = dynamicAttributeKey;
}
/**
* {@inheritDoc}
*/
@Override
protected boolean doApply(DiscoveryEnabledServer server) {
String attributeKey = current().get(dynamicAttributeKey);
Map metadata = server.getInstanceInfo().getMetadata();
if (attributeKey != null) {
String expected = current().get(attributeKey);
String actual = metadata.get(attributeKey);
boolean accept = (expected == null && actual == null) || (expected != null && expected.equals(actual));
log.trace("Expected [{}={}] vs {}{} => {}",
attributeKey,
expected,
server.getHostPort(),
metadata,
accept);
return accept;
} else {
log.trace("[{}] not defined! : {}{} => false",
dynamicAttributeKey,
server.getHostPort(),
metadata);
return false;
}
}
}