Google-Cloud: Jetty ALPN/NPN has not been properly

Getting exception whilst using Google Pubsub to list topics, my web application is running on tomcat.

public static List<String> listTopics(GcpCredentials gcCredentials, String project) throws GCPException, IOException
{
    List<String> topics = new ArrayList<>();
    TopicAdminClient client = getTopicClient(gcCredentials);
    ProjectName projectName = ProjectName.create(project);
    ListTopicsPagedResponse response = client.listTopics(projectName);
    for (Topic topic :response.iterateAll())
    {
        topics.add(topic.getNameAsTopicName().getTopic());
    }
    return topics;
}`

Exception:

java.lang.IllegalArgumentException: Jetty ALPN/NPN has not been properly configured.
at io.grpc.netty.GrpcSslContexts.selectApplicationProtocolConfig(GrpcSslContexts.java:174) at io.grpc.netty.GrpcSslContexts.configure(GrpcSslContexts.java:151) at io.grpc.netty.GrpcSslContexts.configure(GrpcSslContexts.java:139) at io.grpc.netty.GrpcSslContexts.forClient(GrpcSslContexts.java:109) at io.grpc.netty.NettyChannelBuilder.createProtocolNegotiatorByType(NettyChannelBuilder.java:335) at io.grpc.netty.NettyChannelBuilder.createProtocolNegotiator(NettyChannelBuilder.java:308) at io.grpc.netty.NettyChannelBuilder$NettyTransportFactory$DynamicNettyTransportParams.getProtocolNegotiator(NettyChannelBuilder.java:499) at io.grpc.netty.NettyChannelBuilder$NettyTransportFactory.newClientTransport(NettyChannelBuilder.java:448) at io.grpc.internal.CallCredentialsApplyingTransportFactory.newClientTransport(CallCredentialsApplyingTransportFactory.java:61) at io.grpc.internal.InternalSubchannel.startNewTransport(InternalSubchannel.java:209) at io.grpc.internal.InternalSubchannel.obtainActiveTransport(InternalSubchannel.java:186) at io.grpc.internal.ManagedChannelImpl$SubchannelImplImpl.obtainActiveTransport(ManagedChannelImpl.java:806) at io.grpc.internal.GrpcUtil.getTransportFromPickResult(GrpcUtil.java:568) at io.grpc.internal.DelayedClientTransport.reprocess(DelayedClientTransport.java:296) at io.grpc.internal.ManagedChannelImpl$LbHelperImpl$5.run(ManagedChannelImpl.java:724) at io.grpc.internal.ChannelExecutor.drain(ChannelExecutor.java:87) at io.grpc.internal.ManagedChannelImpl$LbHelperImpl.runSerialized(ManagedChannelImpl.java:715) at io.grpc.internal.ManagedChannelImpl$NameResolverListenerImpl.onUpdate(ManagedChannelImpl.java:752) at io.grpc.internal.DnsNameResolver$1.run(DnsNameResolver.java:174) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)

I have observed this problem with Netty version 4.1.15.Final but not with 4.1.13.Final. Check your transitive dependencies. I.e Spring Boot references Netty.

What I added to POM to make it work with Spanner API version 0.22.0-beta:

<properties> <v.netty>4.1.13.Final</v.netty> </properties> ... <dependencyManagement> <dependencies> <dependency> <groupId>io.netty</groupId> <artifactId>netty-codec</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-codec-http</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-codec-http2</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-handler</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-common</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-handler-proxy</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-transport</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-resolver</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-codec-socks</artifactId> <version>${v.netty}</version> </dependency> <dependency> <groupId>io.netty</groupId> <artifactId>netty-buffer</artifactId> <version>${v.netty}</version> </dependency> </dependencies> </dependencyManagement>

If the problem persists, or if it is not an option, plase run your JVM with appropriate bootclasspath entry, like:

java -Xbootclasspath/p:/tmp/alpn-boot-8.1.11.v20170118.jar -cp ...

Make sure to replace /tmp/alpn-boot-8.1.11.v20170118.jar with location of alpn jar that matches your JVM version as listed on this page: https://www.eclipse.org/jetty/documentation/9.4.x/alpn-chapter.html

There is a possible solution on github: "Exception when configuring SSL: "Jetty ALPN/NPN has not been properly configured."

The recommended steps, quoting from the above document:

1) Edit catalina.sh /usr/local/Cellar/tomcat/8.5.3/libexec/bin/catalina.sh

2) At line 103, add the following CATALINA_OPTS="-javaagent:/Library/Tomcat/lib/jetty-alpn-agent-2.0.6.jar"

3) Restart tomcat ../bin/shutdown.sh ../bin/startup.sh