org.apache.catalina.tribes.membership.cloud.DNSMembershipProvider Maven / Gradle / Ivy
/*
* 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.catalina.tribes.membership.cloud;
import java.io.IOException;
import java.io.Serializable;
import java.net.InetAddress;
import java.net.URLEncoder;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.MembershipService;
import org.apache.catalina.tribes.membership.MemberImpl;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
/**
* A {@link org.apache.catalina.tribes.MembershipProvider} that uses DNS to retrieve the members of a cluster.
*
* Configuration example for Kubernetes
*
* {@code server.xml }
*
*
* {@code
*
*
*
*
* ...
* }
*
*
* minimal example for the Service my-tomcat-app-membership, note the selector
* {@code dns-membership-service.yml }
*
*
* {@code
* apiVersion: v1
* kind: Service
* metadata:
* annotations:
* service.alpha.kubernetes.io/tolerate-unready-endpoints: "true"
* description: "The service for tomcat cluster membership."
* name: my-tomcat-app-membership
* spec:
* clusterIP: None
* selector:
* app: my-tomcat-app
* }
*
*
* First Tomcat pod minimal example, note the labels that must correspond to the
* selector in the service.
* {@code tomcat1.yml }
*
*
* {@code
* apiVersion: v1
* kind: Pod
* metadata:
* name: tomcat1
* labels:
* app: my-tomcat-app
* spec:
* containers:
* - name: tomcat
* image: tomcat
* ports:
* - containerPort: 8080
* }
*
*
* Environment variable configuration
* {@code DNS_MEMBERSHIP_SERVICE_NAME=my-tomcat-app-membership }
*/
public class DNSMembershipProvider extends CloudMembershipProvider {
private static final Log log = LogFactory.getLog(DNSMembershipProvider.class);
private String dnsServiceName;
@Override
public void start(int level) throws Exception {
if ((level & MembershipService.MBR_RX) == 0) {
return;
}
super.start(level);
// Set up Kubernetes API parameters
dnsServiceName = getEnv("DNS_MEMBERSHIP_SERVICE_NAME");
if (dnsServiceName == null) {
dnsServiceName = getNamespace();
}
if (log.isDebugEnabled()) {
log.debug(sm.getString("cloudMembershipProvider.start", dnsServiceName));
}
dnsServiceName = URLEncoder.encode(dnsServiceName, "UTF-8");
// Fetch initial members
heartbeat();
}
@Override
public boolean stop(int level) throws Exception {
return super.stop(level);
}
@Override
protected Member[] fetchMembers() {
List members = new ArrayList<>();
InetAddress[] inetAddresses = null;
try {
inetAddresses = InetAddress.getAllByName(dnsServiceName);
} catch (UnknownHostException exception) {
log.warn(sm.getString("dnsMembershipProvider.dnsError", dnsServiceName), exception);
}
if (inetAddresses != null) {
for (InetAddress inetAddress : inetAddresses) {
String ip = inetAddress.getHostAddress();
byte[] id = md5.digest(ip.getBytes());
// We found ourselves, ignore
if (ip.equals(localIp)) {
// Update the UID on initial lookup
Member localMember = service.getLocalMember(false);
if (localMember.getUniqueId() == CloudMembershipService.INITIAL_ID &&
localMember instanceof MemberImpl) {
((MemberImpl) localMember).setUniqueId(id);
}
continue;
}
long aliveTime = -1;
MemberImpl member = null;
try {
member = new MemberImpl(ip, port, aliveTime);
} catch (IOException e) {
log.error(sm.getString("kubernetesMembershipProvider.memberError"), e);
continue;
}
member.setUniqueId(id);
members.add(member);
}
}
return members.toArray(new Member[0]);
}
@Override
public boolean accept(Serializable msg, Member sender) {
// Check if the sender is in the member list.
boolean found = false;
Member[] members = membership.getMembers();
if (members != null) {
for (Member member : members) {
if (Arrays.equals(sender.getHost(), member.getHost()) && sender.getPort() == member.getPort()) {
found = true;
break;
}
}
}
if (!found) {
MemberImpl member = new MemberImpl();
member.setHost(sender.getHost());
member.setPort(sender.getPort());
byte[] host = sender.getHost();
int i = 0;
StringBuilder buf = new StringBuilder();
buf.append(host[i++] & 0xff);
for (; i < host.length; i++) {
buf.append('.').append(host[i] & 0xff);
}
byte[] id = md5.digest(buf.toString().getBytes());
member.setUniqueId(id);
member.setMemberAliveTime(-1);
updateMember(member, true);
}
return false;
}
}