Exception when configuring SSL: "Jetty ALPN/NPN has not been properly configured." (and possible solution)

I am unable to configure an SSL gRPC.

SslContextBuilder sslBuilder = GrpcSslContexts.forServer(new File("a"), new File("b"))
sslBuilder.build();

Causes this exception:

Exception in thread "main" java.lang.IllegalArgumentException: Jetty ALPN/NPN has not been properly configured.
        at io.grpc.netty.GrpcSslContexts.selectApplicationProtocolConfig(GrpcSslContexts.java:143)
        at io.grpc.netty.GrpcSslContexts.configure(GrpcSslContexts.java:120)
        at io.grpc.netty.GrpcSslContexts.configure(GrpcSslContexts.java:109)
        at io.grpc.netty.GrpcSslContexts.forServer(GrpcSslContexts.java:90)

I think the root cause is here:

/**
   * Indicates whether or not the Jetty ALPN jar is installed in the boot classloader.
   */
  static boolean isJettyAlpnConfigured() {
    try {
      Class.forName("org.eclipse.jetty.alpn.ALPN", true, null);
      return true;
    } catch (ClassNotFoundException e) {
      return false;
    }
  }

This method is restricting the search to the boot classloader, which I don’t think is correct. i.e. in the following code, the first line executes fine, but the second line throws CNFE (despite the class being loaded), causing isJettyAlpnConfigured() to return false:

System.out.println("Class loaded? " + org.eclipse.jetty.alpn.ALPN.class);
System.out.println("Maybe not: " + Class.forName("org.eclipse.jetty.alpn.ALPN", true, null));

I suspect the Class.forName(String) variant should be used instead (which doesn’t throw CNFE), but maybe there was some good rationale for restricting to the boot classpath?

FWIW I am using alpn-api-1.1.2.v20150522.jar with the following other deps: grpc-all-0.9.0.jar hpack-0.10.1.jar netty-all-4.1.0.Beta6.jar okhttp-2.4.0.jar okio-1.6.0.jar protobuf-java-3.0.0-beta-1.jar

[qiang-dai]

This is my way:

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

[prayagupa]

For non-tomcat app, I could make it work with -javaagent on CentOS; which is documented in https://github.com/grpc/grpc-java/blob/master/SECURITY.md#tls-with-jdk-jetty-alpnnpn. BUT For some reason does not require jetty-alpn on MacOS.

wget http://central.maven.org/maven2/org/mortbay/jetty/alpn/jetty-alpn-agent/2.0.7/jetty-alpn-agent-2.0.7.jar

/home/prayagupd/jdk1.8.0_161/bin/java -jar 
-Djavax.net.ssl.keyStore=/home/prayagupd/keystore/keystore.jks 
-Djavax.net.ssl.keyStorePassword=password 
-Djavax.net.ssl.trustStore=/home/prayagupd/keystore/truststore.jks 
-Djavax.net.ssl.trustStorePassword=password 
-javaagent:jetty-alpn-agent-2.0.7.jar nlu-intent-toolkit.jar test-agent "music venues near me?" credentials.json