Hazelcast multicast does not work because of vboxnet which is used by docker-machine

Question

After installation of dockerForMac and virtualbox on my macOs, local hazelcast members can not see each others with the multicast configuration of hazelcast (not in containers). It seems both of them are master in the cluster with the different port.

Difference after installation of docker stuff etc. is IP addresses of the members. It was my local IP address but now It has 192.168.99.1 is used by vboxnet. see my ifconfig.

This comment is about the port usage of multicast discovery function: It looks like Hazelcast uses multicast address 224.2.2.3 on UDP port 54327 (by default) for discovery, and then port 5701 for TCP communication. Opening UDP port 54327 in the firewall fixed discovery for me. (I had also opened TCP port 5701 but that was not sufficient.)

Is there anyway to make hazelcast use to my IP address? or Is there anyway to open these ports for vnetbox?

ifconfig:

vboxnet0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether XX:XX:XX:00:00:00
vboxnet1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether XX:XX:XX:00:00:01
    inet 192.168.99.1 netmask 0xffffff00 broadcast 192.168.99.255

Node-1:

2017-09-21 12:52:20.882 DEBUG 74783 --- [           main] c.h.i.cluster.impl.MulticastJoiner       : [192.168.99.1]:5701 [OSMAN] [3.8.4] PostJoin master: [192.168.99.1]:5701, isMaster: true
2017-09-21 12:52:20.882  INFO 74783 --- [           main] c.h.i.cluster.impl.MulticastJoiner       : [192.168.99.1]:5701 [OSMAN] [3.8.4] 

Members [1] {
    Member [192.168.99.1]:5701 - c38919ff-d992-4d2e-a7f8-afaae146e5d5 this
}

2017-09-21 12:52:20.906  INFO 74783 --- [           main] com.hazelcast.core.LifecycleService      : [192.168.99.1]:5701 [OSMAN] [3.8.4] [192.168.99.1]:5701 is STARTED

Node-2:

2017-09-21 12:52:21.513 DEBUG 74800 --- [           main] c.h.i.cluster.impl.MulticastJoiner       : [192.168.99.1]:5702 [test-group] [3.8.4] PostJoin master: [192.168.99.1]:5702, isMaster: true
2017-09-21 12:52:21.513  INFO 74800 --- [           main] c.h.i.cluster.impl.MulticastJoiner       : [192.168.99.1]:5702 [test-group] [3.8.4] 

Members [1] {
    Member [192.168.99.1]:5702 - e21bbd01-b55f-4e6e-8a04-eff4402e300a this
}

2017-09-21 12:52:21.513  WARN 74800 --- [           main] com.hazelcast.instance.Node              : [192.168.99.1]:5702 [test-group] [3.8.4] Config seed port is 5701 and cluster size is 1. Some of the ports seem occupied!

Hazelcast Configuration:

@Bean
public Config hazelCastConfig() {
    Config config = new Config();
    config.getGroupConfig().setName("test-group");
    config.getGroupConfig().setPassword("test-password");
    config.getNetworkConfig().getJoin().getTcpIpConfig().setEnabled(false);
    config.getNetworkConfig().getJoin().getAwsConfig().setEnabled(false);
    config.getNetworkConfig().getJoin().getMulticastConfig().setEnabled(true);
    return config;
}

gokhansari gokhansari · Accepted Answer · 2017-09-21T13:12:37

I changed multicast group to 224.0.0.1 by chance and surprisingly It worked. And members started to see each other.

multicastConfig.setMulticastGroup("224.0.0.1");

Any other IP address for the multicast group between "224.0.0.0 and 239.255.255.255" except 224.0.0.1 does not work.

So in that point; My question is why 224.2.2.3 is selected as default multicast group IP address? It does not work vboxnet adapter.

It seems description of 224.0.0.1 is "The All Hosts multicast group addresses all hosts on the same network segment." which means it should be default value for the multicast group IP address

Hazelcast multicast does not work because of vboxnet which is used by docker-machine

1 Answers