replace NettyChannelBuilder.nameResolverFactory

[usertree]

Grpc load balancing needs to be used, but the method nameResolverFactory() has been abandoned. How to replace it？

[voidzcy]

As the Javadoc says, if you are implementing your own resolver, you'd implement a provider for it. Then you'd either need to register your provider to the global registry, either with SPI mechanism or do it manually. Then you do not need to provide the name resolver factory to the channel builder, the channel can select it automatically from the registry.

[voidzcy]

#7133 is the issue for encouraging migrating away from NameResolver.Factory related APIs.

[usertree]

@voidzcy I tried to add resolver and provider,but a new error was reported

Caused by: io.grpc.StatusRuntimeException: UNAVAILABLE: io exception\nChannel Pipeline: [SslHandler#0, ProtocolNegotiators$ClientTlsHandler#0, WriteBufferingAndExceptionHandler#0, DefaultChannelPipeline$TailContext#0]
        at io.grpc.Status.asRuntimeException(Status.java:533)
        at io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:533)
        at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:616)
        at io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:69)
        at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInternal(ClientCallImpl.java:802)
        at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:781)
        at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)
        at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:123)
        ... 3 more
Caused by: javax.net.ssl.SSLHandshakeException: General SSLEngine problem
        at sun.security.ssl.Handshaker.checkThrown(Handshaker.java:1566)
        at sun.security.ssl.SSLEngineImpl.checkTaskThrown(SSLEngineImpl.java:545)
        at sun.security.ssl.SSLEngineImpl.writeAppRecord(SSLEngineImpl.java:1217)
        at sun.security.ssl.SSLEngineImpl.wrap(SSLEngineImpl.java:1185)
        at javax.net.ssl.SSLEngine.wrap(SSLEngine.java:511)
        at io.netty.handler.ssl.JdkSslEngine.wrap(JdkSslEngine.java:82)
        at io.netty.handler.ssl.JdkAlpnSslEngine.wrap(JdkAlpnSslEngine.java:133)
        at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:1079)
        at io.netty.handler.ssl.SslHandler.wrapNonAppData(SslHandler.java:970)
        at io.netty.handler.ssl.SslHandler.access$1800(SslHandler.java:167)
        at io.netty.handler.ssl.SslHandler$SslTasksRunner.resumeOnEventExecutor(SslHandler.java:1706)
        at io.netty.handler.ssl.SslHandler$SslTasksRunner.access$2000(SslHandler.java:1586)
        at io.netty.handler.ssl.SslHandler$SslTasksRunner$1.run(SslHandler.java:1746)
        at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
        at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        ... 1 more
Caused by: javax.net.ssl.SSLHandshakeException: General SSLEngine problem
        at sun.security.ssl.Alerts.getSSLException(Alerts.java:198)
        at sun.security.ssl.SSLEngineImpl.fatal(SSLEngineImpl.java:1729)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:333)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:325)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1688)
        at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:226)
        at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1082)
        at sun.security.ssl.Handshaker$1.run(Handshaker.java:1015)
        at sun.security.ssl.Handshaker$1.run(Handshaker.java:1012)
        at java.security.AccessController.doPrivileged(Native Method)
        at sun.security.ssl.Handshaker$DelegatedTask.run(Handshaker.java:1504)
        at io.netty.handler.ssl.SslHandler.runAllDelegatedTasks(SslHandler.java:1550)
        at io.netty.handler.ssl.SslHandler.access$1900(SslHandler.java:167)
        at io.netty.handler.ssl.SslHandler$SslTasksRunner.run(SslHandler.java:1737)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        ... 1 more
Caused by: java.security.cert.CertificateException: No subject alternative DNS name matching etcd found.
        at sun.security.util.HostnameChecker.matchDNS(HostnameChecker.java:215)
        at sun.security.util.HostnameChecker.match(HostnameChecker.java:97)
        at sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:462)
        at sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:442)
        at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:261)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:144)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1675)
        ... 12 more

[voidzcy]

I saw Caused by: java.security.cert.CertificateException: No subject alternative DNS name matching etcd found.. It looks you are probably running on test environment (as your hostname is etcd). You can use ManagedChannelBuilder.overrideAuthority(...) to override the hostname used for TLS hostname verification to match the hostname in your test cert.

[ejona86]

@usertree, it seems you are trying to override the DNS name resolver with your own. Make sure to return a value larger than 5 from your provider's priority() method. I'd suggest a value of 7.

[usertree]

@voidzcy @ejona86 Thank you. The problem is solved