前提
Nacos 支持单机部署以及集群部署
- 针对单机模式,Nacos 只是自己和自己通信;
- 对于集群模式,则集群内的每个 Nacos 成员都需要相互通信。
因此这就带来⼀个问题,该以何种方式去管理集群内的 Nacos 成员节点信息,而这,就是 Nacos 内部的寻址机制。
设计
无论是单机模式,还是集群模式,其根本区别只是 Nacos 成员节点的个数是单个还是多个
-
要能够感知到节点的变更情况:节点是增加了还是减少了;
-
当前最新的成员列表信息是什么;
-
以何种方式去管理成员列表信息;
-
如何快速的支持新的、更优秀的成员列表管理模式等等。
MemberLookup
针对上述需求点,抽象出了⼀个 MemberLookup 接口
package com.alibaba.nacos.core.cluster;
import com.alibaba.nacos.api.exception.NacosException;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
/**
* Member node addressing mode.
*
* @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
*/
public interface MemberLookup {
/**
* start.
*
* @throws NacosException NacosException
*/
void start() throws NacosException;
/**
* is using address server.
*
* @return using address server or not.
*/
boolean useAddressServer();
/**
* Inject the ServerMemberManager property.
*
* @param memberManager {@link ServerMemberManager}
*/
void injectMemberManager(ServerMemberManager memberManager);
/**
* The addressing pattern finds cluster nodes.
*
* @param members {@link Collection}
*/
void afterLookup(Collection<Member> members);
/**
* Addressing mode closed.
*
* @throws NacosException NacosException
*/
void destroy() throws NacosException;
/**
* Some data information about the addressing pattern.
*
* @return {@link Map}
*/
default Map<String, Object> info() {
return Collections.emptyMap();
}
}
-
ServerMemberManager
存储着本节点所知道的所有成员节点列表信息,提供了针对成员节点的增删改查操作,同时维护了⼀个 MemberLookup 列表,方便进行动态切换成员节点寻址方式。 -
MemberLookup
接口非常简单,核心接口就两个—injectMemberManager
以及afterLookup
,前者用于将ServerMemberManager
注入到MemberLookup
中,方便利用ServerMemberManager
的存储、查询能力,后者afterLookup
则是⼀个事件接口,当MemberLookup
需要进行成员节点信息更新时,会将当前最新的成员节点列表信息通过该函数进行通知给ServerMemberManager
,具体的节点管理方式,则是隐藏到具体的MemberLookup
实现中。
内部实现
单机寻址 StandaloneMemberLookup
单机模式的寻址模式很简单,其实就是找到自己的 IP:PORT 组合信息,然后格式化为⼀个节点信息,调用 afterLookup 然后将信息存储到 ServerMemberManager 中。
package com.alibaba.nacos.core.cluster.lookup;
import com.alibaba.nacos.core.cluster.AbstractMemberLookup;
import com.alibaba.nacos.core.cluster.MemberUtil;
import com.alibaba.nacos.sys.env.EnvUtil;
import com.alibaba.nacos.sys.utils.InetUtils;
import java.util.Collections;
/**
* Member node addressing mode in stand-alone mode.
*
* @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
*/
public class StandaloneMemberLookup extends AbstractMemberLookup {
@Override
public void doStart() {
String url = InetUtils.getSelfIP() + ":" + EnvUtil.getPort();
afterLookup(MemberUtil.readServerConf(Collections.singletonList(url)));
}
@Override
public boolean useAddressServer() {
return false;
}
}
文件寻址 FileConfigMemberLookup
文件寻址模式是 Nacos 集群模式下的默认寻址实现。
文件寻址模式很简单,其实就是每个 Nacos节点需要维护⼀个叫做 cluster.conf 的文件。
192.168.16.101:8847
192.168.16.102
192.168.16.103
该文件默认只需要填写每个成员节点的 IP 信息即可,端口会自动选择 Nacos 的默认端口 8848,如过说有特殊需求更改了 Nacos 的端口信息,则需要在该文件将该节点的完整网路地址信息补充完整(IP:PORT)。
当 Nacos 节点启动时,会读取该文件的内容,然后将文件内的 IP 解析为节点列表,调用 afterLookup 存入 ServerMemberManager
/**
* Cluster.conf file managed cluster member node addressing pattern.
*
* @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
*/
public class FileConfigMemberLookup extends AbstractMemberLookup {
private static final String DEFAULT_SEARCH_SEQ = "cluster.conf";
private FileWatcher watcher = new FileWatcher() {
@Override
public void onChange(FileChangeEvent event) {
readClusterConfFromDisk();
}
@Override
public boolean interest(String context) {
return StringUtils.contains(context, DEFAULT_SEARCH_SEQ);
}
};
@Override
public void doStart() throws NacosException {
readClusterConfFromDisk();
// Use the inotify mechanism to monitor file changes and automatically
// trigger the reading of cluster.conf
try {
WatchFileCenter.registerWatcher(EnvUtil.getConfPath(), watcher);
} catch (Throwable e) {
Loggers.CLUSTER.error("An exception occurred in the launch file monitor : {}", e.getMessage());
}
}
@Override
public boolean useAddressServer() {
return false;
}
@Override
public void destroy() throws NacosException {
WatchFileCenter.deregisterWatcher(EnvUtil.getConfPath(), watcher);
}
private void readClusterConfFromDisk() {
Collection<Member> tmpMembers = new ArrayList<>();
try {
List<String> tmp = EnvUtil.readClusterConf();
tmpMembers = MemberUtil.readServerConf(tmp);
} catch (Throwable e) {
Loggers.CLUSTER
.error("nacos-XXXX [serverlist] failed to get serverlist from disk!, error : {}", e.getMessage());
}
afterLookup(tmpMembers);
}
}
如果发现集群扩缩容,那么就需要修改每个 Nacos 节点下的 cluster.conf 文件,然后 Nacos 内部的文件变动监听中心会自动发现文件修改,重新读取文件内容、加载 IP 列表信息、更新新增的节点 (FileWatcher)
但是,这种默认寻址模式有⼀个缺点——运维成本较大,可以想象下,当你新增⼀个 Nacos 节点时,需要去手动修改每个 Nacos 节点下的 cluster.conf 文件,这是多么辛苦的⼀件工作,或者稍微高端⼀点,利用 ansible 等自动化部署的工具去推送 cluster.conf 文件去代替自己的手动操作,虽然说省去了较为繁琐的人工操作步骤,但是仍旧存在⼀个问题——每⼀个 Nacos 节点都存在⼀份cluster.conf 文件,如果其中⼀个节点的 cluster.conf 文件修改失败,就造成了集群间成员节点列表数据的不⼀致性,因此,又引申出了新的寻址模式——地址服务器寻址模式
地址服务器寻址 AddressServerMemberLookup
地址服务器寻址模式是 Nacos 官方推荐的⼀种集群成员节点信息管理,该模式利用了⼀个简易的web 服务器,用于管理 cluster.conf 文件的内容信息,这样,运维人员只需要管理这⼀份集群成员节点内容即可,而每个 Nacos 成员节点,只需要向这个 web 节点定时请求当前最新的集群成员节点列表信息即可。
public class AddressServerMemberLookup extends AbstractMemberLookup {
private final GenericType<String> genericType = new GenericType<String>() { };
public String domainName;
public String addressPort;
public String addressUrl;
public String envIdUrl;
public String addressServerUrl;
private volatile boolean isAddressServerHealth = true;
private int addressServerFailCount = 0;
private int maxFailCount = 12;
private final NacosRestTemplate restTemplate = HttpClientBeanHolder.getNacosRestTemplate(Loggers.CORE);
private volatile boolean shutdown = false;
private static final String HEALTH_CHECK_FAIL_COUNT_PROPERTY = "maxHealthCheckFailCount";
private static final String DEFAULT_HEALTH_CHECK_FAIL_COUNT = "12";
private static final String DEFAULT_SERVER_DOMAIN = "jmenv.tbsite.net";
private static final String DEFAULT_SERVER_POINT = "8080";
private static final int DEFAULT_SERVER_RETRY_TIME = 5;
private static final long DEFAULT_SYNC_TASK_DELAY_MS = 5_000L;
private static final String ADDRESS_SERVER_DOMAIN_ENV = "address_server_domain";
private static final String ADDRESS_SERVER_DOMAIN_PROPERTY = "address.server.domain";
private static final String ADDRESS_SERVER_PORT_ENV = "address_server_port";
private static final String ADDRESS_SERVER_PORT_PROPERTY = "address.server.port";
private static final String ADDRESS_SERVER_URL_ENV = "address_server_url";
private static final String ADDRESS_SERVER_URL_PROPERTY = "address.server.url";
private static final String ADDRESS_SERVER_RETRY_PROPERTY = "nacos.core.address-server.retry";
@Override
public void doStart() throws NacosException {
this.maxFailCount = Integer.parseInt(EnvUtil.getProperty(HEALTH_CHECK_FAIL_COUNT_PROPERTY, DEFAULT_HEALTH_CHECK_FAIL_COUNT));
initAddressSys();
run();
}
@Override
public boolean useAddressServer() {
return true;
}
private void initAddressSys() {
String envDomainName = System.getenv(ADDRESS_SERVER_DOMAIN_ENV);
if (StringUtils.isBlank(envDomainName)) {
domainName = EnvUtil.getProperty(ADDRESS_SERVER_DOMAIN_PROPERTY, DEFAULT_SERVER_DOMAIN);
} else {
domainName = envDomainName;
}
String envAddressPort = System.getenv(ADDRESS_SERVER_PORT_ENV);
if (StringUtils.isBlank(envAddressPort)) {
addressPort = EnvUtil.getProperty(ADDRESS_SERVER_PORT_PROPERTY, DEFAULT_SERVER_POINT);
} else {
addressPort = envAddressPort;
}
String envAddressUrl = System.getenv(ADDRESS_SERVER_URL_ENV);
if (StringUtils.isBlank(envAddressUrl)) {
addressUrl = EnvUtil.getProperty(ADDRESS_SERVER_URL_PROPERTY, EnvUtil.getContextPath() + "/" + "serverlist");
} else {
addressUrl = envAddressUrl;
}
addressServerUrl = "http://" + domainName + ":" + addressPort + addressUrl;
envIdUrl = "http://" + domainName + ":" + addressPort + "/env";
Loggers.CORE.info("ServerListService address-server port:" + addressPort);
Loggers.CORE.info("ADDRESS_SERVER_URL:" + addressServerUrl);
}
@SuppressWarnings("PMD.UndefineMagicConstantRule")
private void run() throws NacosException {
// With the address server, you need to perform a synchronous member node pull at startup
// Repeat three times, successfully jump out
boolean success = false;
Throwable ex = null;
int maxRetry = EnvUtil.getProperty(ADDRESS_SERVER_RETRY_PROPERTY, Integer.class, DEFAULT_SERVER_RETRY_TIME);
for (int i = 0; i < maxRetry; i++) {
try {
syncFromAddressUrl();
success = true;
break;
} catch (Throwable e) {
ex = e;
Loggers.CLUSTER.error("[serverlist] exception, error : {}", ExceptionUtil.getAllExceptionMsg(ex));
}
}
if (!success) {
throw new NacosException(NacosException.SERVER_ERROR, ex);
}
GlobalExecutor.scheduleByCommon(new AddressServerSyncTask(), DEFAULT_SYNC_TASK_DELAY_MS);
}
@Override
public void destroy() throws NacosException {
shutdown = true;
}
@Override
public Map<String, Object> info() {
Map<String, Object> info = new HashMap<>(4);
info.put("addressServerHealth", isAddressServerHealth);
info.put("addressServerUrl", addressServerUrl);
info.put("envIdUrl", envIdUrl);
info.put("addressServerFailCount", addressServerFailCount);
return info;
}
private void syncFromAddressUrl() throws Exception {
RestResult<String> result = restTemplate
.get(addressServerUrl, Header.EMPTY, Query.EMPTY, genericType.getType());
if (result.ok()) {
isAddressServerHealth = true;
Reader reader = new StringReader(result.getData());
try {
afterLookup(MemberUtil.readServerConf(EnvUtil.analyzeClusterConf(reader)));
} catch (Throwable e) {
Loggers.CLUSTER.error("[serverlist] exception for analyzeClusterConf, error : {}",
ExceptionUtil.getAllExceptionMsg(e));
}
addressServerFailCount = 0;
} else {
addressServerFailCount++;
if (addressServerFailCount >= maxFailCount) {
isAddressServerHealth = false;
}
Loggers.CLUSTER.error("[serverlist] failed to get serverlist, error code {}", result.getCode());
}
}
class AddressServerSyncTask implements Runnable {
@Override
public void run() {
if (shutdown) {
return;
}
try {
syncFromAddressUrl();
} catch (Throwable ex) {
addressServerFailCount++;
if (addressServerFailCount >= maxFailCount) {
isAddressServerHealth = false;
}
Loggers.CLUSTER.error("[serverlist] exception, error : {}", ExceptionUtil.getAllExceptionMsg(ex));
} finally {
GlobalExecutor.scheduleByCommon(this, DEFAULT_SYNC_TASK_DELAY_MS);
}
}
}
}
因此,通过地址服务器这种模式,大大简化了 Nacos 集群节点管理的成本,同时,地址服务器是⼀个非常简单的 web 程序,其程序的稳定性能够得到很好的保障。
未来可扩展点
集群节点自动扩缩容
目前,Nacos 的集群节点管理,还都是属于人工操作,因此,未来期望能够基于寻址模式,实现集群节点自动管理的功能,能够实现新的节点上线时,只需要知道原有集群中的⼀个节点信息,就可以在⼀定时间内,顺利加入原有 Nacos 集群中;同时,也能够自行发现不存活的节点,自动将其从集群可用节点列表中剔出。这⼀块的逻辑实现,其实就类似 Consul 的 Gossip 协议。文章来源:https://www.toymoban.com/news/detail-481222.html
文章来源地址https://www.toymoban.com/news/detail-481222.html
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