Issues with using Google Cloud natural language grpc API on java 8 appengine standard

[Anand Srinivasan]

We recently started looking into switching to java 8 so that we can use the myriad benefits that it offers including grpc. We tried using grpc for the google cloud natural language API but we were unable to get that to work. Here is the stack trace that we hit when trying to make the analyzeSentiment call.

com.google.api.server.spi.SystemService invokeServiceMethod: exception occurred while calling backend method (SystemService.java:398) com.google.api.gax.grpc.ApiException: io.grpc.StatusRuntimeException: UNAUTHENTICATED at com.google.api.gax.grpc.ExceptionTransformingCallable$ExceptionTransformingFuture.onFailure(ExceptionTransformingCallable.java:108) at com.google.api.core.ApiFutures$1.onFailure(ApiFutures.java:53) at com.google.common.util.concurrent.Futures$4.run(Futures.java:1123) at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:435) at com.google.common.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:900) at com.google.common.util.concurrent.AbstractFuture.complete(AbstractFuture.java:811) at com.google.common.util.concurrent.AbstractFuture.setException(AbstractFuture.java:675) at io.grpc.stub.ClientCalls$GrpcFuture.setException(ClientCalls.java:466) at io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:442) at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:426) at io.grpc.internal.ClientCallImpl.access$100(ClientCallImpl.java:76) at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.close(ClientCallImpl.java:512) at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl.access$700(ClientCallImpl.java:429) at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:544) at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:52) at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:117) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:295) 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:745) Caused by: io.grpc.StatusRuntimeException: UNAUTHENTICATED at io.grpc.Status.asRuntimeException(Status.java:543) ... 15 more Caused by: java.io.IOException: Could not get the access token. at com.google.auth.oauth2.AppEngineCredentials.refreshAccessToken(AppEngineCredentials.java:136) at com.google.auth.oauth2.OAuth2Credentials.refresh(OAuth2Credentials.java:149) at com.google.auth.oauth2.OAuth2Credentials.getRequestMetadata(OAuth2Credentials.java:135) at io.grpc.auth.GoogleAuthLibraryCallCredentials$1.run(GoogleAuthLibraryCallCredentials.java:110) ... 7 more Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at com.google.auth.oauth2.AppEngineCredentials.refreshAccessToken(AppEngineCredentials.java:131) ... 10 more Caused by: com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call memcache.Get in a thread that is neither the original request thread nor a thread created by ThreadManager at com.google.apphosting.api.ApiProxy$CallNotFoundException.foreignThread(ApiProxy.java:844) at com.google.apphosting.api.ApiProxy$1.get(ApiProxy.java:183) at com.google.apphosting.api.ApiProxy$1.get(ApiProxy.java:180) at com.google.appengine.api.utils.FutureWrapper.get(FutureWrapper.java:93) at com.google.appengine.api.memcache.MemcacheServiceImpl.quietGet(MemcacheServiceImpl.java:28) at com.google.appengine.api.memcache.MemcacheServiceImpl.get(MemcacheServiceImpl.java:51) at com.google.appengine.api.appidentity.AppIdentityServiceImpl.getAccessToken(AppIdentityServiceImpl.java:300) ... 15 more

The stack trace looks similar to the one posted in this link: https://github.com/GoogleCloudPlatform/google-cloud-java/issues/1918#issuecomment-299004772. It's unclear from the discussion there whether this issue was ever fixed. In either case, what can we do to get around this?

Thanks,

Anand

[Yannick (Cloud Platform Support)]

Hello Anand, 

Whenever you find a reproducible error we strongly encourage that you report it to our Issue Tracker to help us find and fix these issues.

This being said in this particular scenario it appears that the Language API is not yet supported on App Engine Standard. I will attempt to find out if the release of Java 8 for App Engine standard was meant to change this state of affairs.

[Yannick (Cloud Platform Support)]

Hello Anand,

Could you tell me if you were able to use the Natural Language API before? If so how were you doing it? Did you ever use it on App Engine standard?

Also are you able to use the Natural Language API through REST on Java 8 standard?

[Anand Srinivasan]

We have not used it before. We were attempting to use it now and while reading the documentation realized that we could try switching to java 8 at the same time. Did you manage to find out about the status of it being supported on Appengine standard?

Thanks,

Anand

[Yannick (Cloud Platform Support)]

From what I've gathered it does appear that the status of these client libraries hasn't changed and they are still incompatible with App Engine Standard, though they should work on App Engine Flexible. You're also of course free to use them on Compute Engine.

[Emmanuel Charon]

Hi Yannick,

Do you recommend another library to take care of authentication in Java 8 - App Engine Standard ? 

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[Yannick (Cloud Platform Support)]

Hello Emmanuel, it's not clear what kind of authentication you're talking about? If you're not talking about using the Natural Language API on Java 8 please create another discussion thread with context for what you want to discuss.

[KANISHK GUPTA]

Hello Yannick,

Can you confirm the status of Natural Language client library with java 8 standard?