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Date: Mon, 18 Dec 2017 15:07:43 +0100
From: dominik@dbruhn.de
To: user <user@flink.apache.org>
Subject: Flink 1.4 with cassandra-connector: Shading error
Message-ID: <b1f584b918c8aaf98b744c168407b0f5@dbruhn.de>
User-Agent: Roundcube Webmail/1.3.3
archived-at: Mon, 18 Dec 2017 14:07:56 -0000

Hey everyone,
I'm trying to migrate one of my jobs to Flink 1.4 and I'm running into a 
classpath/shading error.

What happens is that when Flink calls into Cluster.connect(), somewhere 
down in the stream, the cassandra library tries to initialize Netty, and 
I'm getting the following exception:

Caused by: java.lang.AssertionError: Cannot locate Netty classes in the 
classpath:java.lang.ClassNotFoundException: 
com.datastax.shaded.netty.channel.Channel.
Full exception here:
https://gist.github.com/anonymous/16a44eabb45ad7f20d551dd29b83d2fb

I think this can be explained very easily:
1. The flink-cassandra-connector-1.4 jar contains the Datastax Cassandra 
driver inside
2. The flink-cassandra-connector-1.4 jar contains a shaded (to 
org.apache.flink.cassandra.shaded.io.netty) netty
3. The DataStax driver executes the following code when it initializes 
netty (in NettyUtils starting line 58):

----
  try {
             Class.forName(String.format("%s.%s.channel.Channel", "io", 
"netty"));
             shaded = false;
         } catch (ClassNotFoundException var9) {
             try {
                 
Class.forName("com.datastax.shaded.netty.channel.Channel");
                 shaded = true;
             } catch (ClassNotFoundException var8) {
                 throw new AssertionError("Cannot locate Netty classes in 
the classpath:" + var8);
             }
         }
----


Neither of the two packages (io.netty.channel and 
com.datastax.shaded.netty.channel.Channel) are available and the shaded 
one from Flink is not in the list and is never used here.

My question: Did anyone ever use the cassandra connector on 1.4. As it 
looks to me it is completely broken and can never work. But maybe I'm 
failing to see something. I don't include netty in my dependencies, that 
could of course fix it, but I'm suspecting I will run into more 
dependency problems then.

Here are my dependencies:
https://gist.github.com/anonymous/565a0ad017976502a62b2919115b31fd

What additional information can I provide?

Thanks,
Dominik