io/netty/resolver/dns/DnsAddressResolverGroup/DnsAddressResolverGroup is not assignable to io/netty/resolver/AddressResolverGroup

[klnlakshmiphilips]

Bug Report

When i try to intialize the redis cluster client with the below code, i get exception as described below.

  RedisURI redisUriCluster = RedisURI.builder().withHost(host).withPort(port).build();
    redisClusterClient = RedisClusterClient.create(redisUriCluster);

Exception Details:
  Location:
    io/lettuce/core/resource/AddressResolverGroupProvider$DefaultDnsAddressResolverGroupWrapper.<clinit>()V @51: putstatic
  Reason:
    Type 'io/netty/resolver/dns/DnsAddressResolverGroup' (current frame, stack[0]) is not assignable to 'io/netty/resolver/AddressResolverGroup'

This exception is triggered from the class io.lettuce.core.resource.AddressResolverGroupProvider in the static block.

The static block have the following code

static {
        boolean dnsResolverAvailable = LettuceClassUtils.isPresent("io.netty.resolver.dns.DnsAddressResolverGroup");
        Object group;
        if (dnsResolverAvailable) {
            logger.debug("Starting with netty's non-blocking DNS resolver library");
            group = AddressResolverGroupProvider.DefaultDnsAddressResolverGroupWrapper.INSTANCE;
        } else {
            logger.debug("Starting without optional netty's non-blocking DNS resolver library");
            group = DefaultAddressResolverGroup.INSTANCE;
        }

        ADDRESS_RESOLVER_GROUP = (AddressResolverGroup)group;
    }

As per this code when the class "io.netty.resolver.dns.DnsAddressResolverGroup" is part of the classapath and java is able to load the class, then the boolean value will be true.

As i am running my flink job in EMR the hadoop have a jar netty-resolver-dns-4.1.77.Final.jar in the class path. And this Jar have the class "io.netty.resolver.dns.DnsAddressResolverGroup". After the condition is true, the following code gets executed and throws the above exception

private static class DefaultDnsAddressResolverGroupWrapper {
        static AddressResolverGroup<?> INSTANCE = new DnsAddressResolverGroup((new DnsNameResolverBuilder()).channelType(Transports.datagramChannelClass()).socketChannelType(Transports.socketChannelClass().asSubclass(SocketChannel.class)).cnameCache(new DefaultDnsCnameCache()).resolveCache(new DefaultDnsCache()));

        private DefaultDnsAddressResolverGroupWrapper() {
        }
    }

Current Behavior

Stack trace

Exception Details:
Location:
io/lettuce/core/resource/AddressResolverGroupProvider$DefaultDnsAddressResolverGroupWrapper.()V @51: putstatic
Reason:
Type 'io/netty/resolver/dns/DnsAddressResolverGroup' (current frame, stack[0]) is not assignable to 'io/netty/resolver/AddressResolverGroup'
Current Frame:
bci: @51
flags: { }
locals: { }
stack: { 'io/netty/resolver/dns/DnsAddressResolverGroup' }

Input Code

Input Code

RedisURI redisUriCluster = RedisURI.builder().withHost(host).withPort(port).build();
redisClusterClient = RedisClusterClient.create(redisUriCluster);

Expected behavior/code

Environment

• Lettuce version(s): 6.3.1.RELEASE
• Redis version: AWS ElasticCache for Redis 7.1.0

Possible Solution

Additional context

[tishun]

Hey @klnlakshmiphilips ,

could you verify that the io.netty:netty-resolver-dns-4.1.77.Final.jar and the io.netty:netty-resolver-4.1.77.Final.jar are both present in the classpath and both share the same version ?