grpc-example-Client-side Load Balancing w/ Kubernetes API Service Discovery

[Tarek M. Sayed]

I followed the steps:
$ kubectl apply -f kubernetes/client-side-lb-api/echo-server.yaml
$ kubectl apply -f kubernetes/client-side-lb-api/echo-client.yaml
$ kubectl get pods -l run=echo-client
with this step:
$ kubectl logs -f echo-client...
I found java error

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Nov 28, 2019 2:07:04 PM io.grpc.internal.ManagedChannelImpl$NameResolverListenerImpl onError
WARNING: [io.grpc.internal.ManagedChannelImpl-1] Failed to resolve name. status=Status{code=UNKNOWN, description=null, cause=io.fabric8.kubernetes.client.KubernetesClientException: An error has occurred.
at io.fabric8.kubernetes.client.KubernetesClientException.launderThrowable(KubernetesClientException.java:61)
at io.fabric8.kubernetes.client.KubernetesClientException.launderThrowable(KubernetesClientException.java:52)
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.get(BaseOperation.java:195)
at com.example.grpc.client.KubernetesNameResolver.refresh(KubernetesNameResolver.java:79)
at com.example.grpc.client.KubernetesNameResolver.start(KubernetesNameResolver.java:63)
at io.grpc.internal.ManagedChannelImpl.exitIdleMode(ManagedChannelImpl.java:311)
at io.grpc.internal.ManagedChannelImpl$4$1.run(ManagedChannelImpl.java:357)
at io.grpc.internal.ChannelExecutor.drain(ChannelExecutor.java:87)
at io.grpc.internal.ManagedChannelImpl$4.get(ManagedChannelImpl.java:359)
at io.grpc.internal.ClientCallImpl.start(ClientCallImpl.java:218)
at io.grpc.stub.ClientCalls.startCall(ClientCalls.java:276)
at io.grpc.stub.ClientCalls.asyncUnaryRequestCall(ClientCalls.java:252)
at io.grpc.stub.ClientCalls.futureUnaryCall(ClientCalls.java:186)
at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:132)
at com.example.grpc.EchoServiceGrpc$EchoServiceBlockingStub.echo(EchoServiceGrpc.java:138)
at com.example.grpc.client.ClientSideLoadBalancedEchoClient.lambda$main$0(ClientSideLoadBalancedEchoClient.java:63)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.UnknownHostException: kubernetes.default.svc: Temporary failure in name resolution
at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
at java.net.InetAddress.getAllByName(InetAddress.java:1192)
at java.net.InetAddress.getAllByName(InetAddress.java:1126)
at okhttp3.Dns$1.lookup(Dns.java:39)
at okhttp3.internal.connection.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:172)
at okhttp3.internal.connection.RouteSelector.nextProxy(RouteSelector.java:138)
at okhttp3.internal.connection.RouteSelector.next(RouteSelector.java:80)
at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:178)
at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:129)
at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:98)
at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:109)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:124)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at io.fabric8.kubernetes.client.utils.HttpClientUtils$3.intercept(HttpClientUtils.java:97)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:92)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:67)
at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:170)
at okhttp3.RealCall.execute(RealCall.java:60)
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:235)
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:230)
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleGet(OperationSupport.java:226)
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.handleGet(BaseOperation.java:708)
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.get(BaseOperation.java:188)
... 17 more
}

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.3", GitCommit:"b3cbbae08ec52a7fc73d334838e18d17e8512749", GitTreeState:"clean", BuildDate:"2019-11-13T11:23:11Z", GoVersion:"go1.12.12", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"16", GitVersion:"v1.16.3", GitCommit:"b3cbbae08ec52a7fc73d334838e18d17e8512749", GitTreeState:"clean", BuildDate:"2019-11-13T11:13:49Z", GoVersion:"go1.12.12", Compiler:"gc", Platform:"linux/amd64"}