记一个容器中 dubbo 注册的小知识点
在目前环境下使用容器部署Java应用还是挺普遍的，但是有一些问题也是随之而来需要解决的，比如容器中应用的dubbo注册，在比较早的版本的dubbo中，就是简单地获取网卡的ip地址。
具体代码在这个方法里 com.alibaba.dubbo.config.ServiceConfig#doExportUrlsFor1Protocol1
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43private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
String name = protocolConfig.getName();
if (name == null || name.length() == 0) {
name = "dubbo";
}
String host = protocolConfig.getHost();
if (provider != null && (host == null || host.length() == 0)) {
host = provider.getHost();
}
boolean anyhost = false;
if (NetUtils.isInvalidLocalHost(host)) {
anyhost = true;
try {
host = InetAddress.getLocalHost().getHostAddress();
} catch (UnknownHostException e) {
logger.warn(e.getMessage(), e);
}
if (NetUtils.isInvalidLocalHost(host)) {
if (registryURLs != null && registryURLs.size() > 0) {
for (URL registryURL : registryURLs) {
try {
Socket socket = new Socket();
try {
SocketAddress addr = new InetSocketAddress(registryURL.getHost(), registryURL.getPort());
socket.connect(addr, 1000);
host = socket.getLocalAddress().getHostAddress();
break;
} finally {
try {
socket.close();
} catch (Throwable e) {}
}
} catch (Exception e) {
logger.warn(e.getMessage(), e);
}
}
}
if (NetUtils.isInvalidLocalHost(host)) {
host = NetUtils.getLocalHost();
}
}
}
通过jdk自带的方法 java.net.InetAddress#getLocalHost来获取本机地址，这样子对于容器来讲，获取到容器内部ip注册上去其实是没办法被调用到的，
而在之后的版本中例如dubbo 2.6.5，则可以通过在docker中设置环境变量的形式来注入docker所在的宿主机地址，
代码同样在com.alibaba.dubbo.config.ServiceConfig#doExportUrlsFor1Protocol这个方法中，但是获取host的方法变成了 com.alibaba.dubbo.config.ServiceConfig#findConfigedHosts1
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68private String findConfigedHosts(ProtocolConfig protocolConfig, List<URL> registryURLs, Map<String, String> map) {
boolean anyhost = false;
String hostToBind = getValueFromConfig(protocolConfig, Constants.DUBBO_IP_TO_BIND);
if (hostToBind != null && hostToBind.length() > 0 && isInvalidLocalHost(hostToBind)) {
throw new IllegalArgumentException("Specified invalid bind ip from property:" + Constants.DUBBO_IP_TO_BIND + ", value:" + hostToBind);
}
// if bind ip is not found in environment, keep looking up
if (hostToBind == null || hostToBind.length() == 0) {
hostToBind = protocolConfig.getHost();
if (provider != null && (hostToBind == null || hostToBind.length() == 0)) {
hostToBind = provider.getHost();
}
if (isInvalidLocalHost(hostToBind)) {
anyhost = true;
try {
hostToBind = InetAddress.getLocalHost().getHostAddress();
} catch (UnknownHostException e) {
logger.warn(e.getMessage(), e);
}
if (isInvalidLocalHost(hostToBind)) {
if (registryURLs != null && !registryURLs.isEmpty()) {
for (URL registryURL : registryURLs) {
if (Constants.MULTICAST.equalsIgnoreCase(registryURL.getParameter("registry"))) {
// skip multicast registry since we cannot connect to it via Socket
continue;
}
try {
Socket socket = new Socket();
try {
SocketAddress addr = new InetSocketAddress(registryURL.getHost(), registryURL.getPort());
socket.connect(addr, 1000);
hostToBind = socket.getLocalAddress().getHostAddress();
break;
} finally {
try {
socket.close();
} catch (Throwable e) {
}
}
} catch (Exception e) {
logger.warn(e.getMessage(), e);
}
}
}
if (isInvalidLocalHost(hostToBind)) {
hostToBind = getLocalHost();
}
}
}
}
map.put(Constants.BIND_IP_KEY, hostToBind);
// registry ip is not used for bind ip by default
String hostToRegistry = getValueFromConfig(protocolConfig, Constants.DUBBO_IP_TO_REGISTRY);
if (hostToRegistry != null && hostToRegistry.length() > 0 && isInvalidLocalHost(hostToRegistry)) {
throw new IllegalArgumentException("Specified invalid registry ip from property:" + Constants.DUBBO_IP_TO_REGISTRY + ", value:" + hostToRegistry);
} else if (hostToRegistry == null || hostToRegistry.length() == 0) {
// bind ip is used as registry ip by default
hostToRegistry = hostToBind;
}
map.put(Constants.ANYHOST_KEY, String.valueOf(anyhost));
return hostToRegistry;
}
String hostToRegistry = getValueFromConfig(protocolConfig, Constants.DUBBO_IP_TO_REGISTRY);
就是这一行，1
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8private String getValueFromConfig(ProtocolConfig protocolConfig, String key) {
String protocolPrefix = protocolConfig.getName().toUpperCase() + "_";
String port = ConfigUtils.getSystemProperty(protocolPrefix + key);
if (port == null || port.length() == 0) {
port = ConfigUtils.getSystemProperty(key);
}
return port;
}
也就是配置了DUBBO_IP_TO_REGISTRY这个环境变量