docker-compose-swarm kafka unable to connect zookeeper

[csifinos]

I have used the docker-compose-swarm.yml with docker stack, but the Kafka could not connect with zookeeper.

The command that I executed docker stack deploy -c docker-compose-swarm.yml test

The error is the following:

INFO Socket error occurred: zookeeper/10.0.1.2:2181: Connection refused (org.apache.zookeeper.ClientCnxn)
INFO Opening socket connection to server zookeeper/10.0.1.2:2181. Will not attempt to authenticate using SASL (unknown error) (org.apache.zookeeper.ClientCnxn)

I believe the problem is on the virtual IP of Zookeeper's service (KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181) which is not exactly the same as Zookeeper's IP (Zookeeper Virtual IP 10.0.1.2 and Zookeeper IP 10.0.1.3).

Please find below also the results (only the networks) of "docker inspect zookeeperId":

"Networks": {
	"test_default": {
		"IPAMConfig": {
			"IPv4Address": "10.0.1.3"
		},
		"Links": null,
		"Aliases": [
			"8a31389d113b"
		],
		"NetworkID": "xfyyq1bht5h172h0cx70kesed",
		"EndpointID": "7df594b8bbccd58e39d81daf583cd1915d7fdf7b2341275a8450ed03b89e1876",
		"Gateway": "",
		"IPAddress": "10.0.1.3",
		"IPPrefixLen": 24,
		"IPv6Gateway": "",
		"GlobalIPv6Address": "",
		"GlobalIPv6PrefixLen": 0,
		"MacAddress": "02:42:0a:00:01:03",
		"DriverOpts": null
	},
	"ingress": {
		"IPAMConfig": {
			"IPv4Address": "10.255.0.6"
		},
		"Links": null,
		"Aliases": [
			"8a31389d113b"
		],
		"NetworkID": "84w6cqxuluawi9knheaibgsz3",
		"EndpointID": "27d4bdb8b83356fd82cdf996b19b00d471e8b280967ddff91a3e165bd91245b9",
		"Gateway": "",
		"IPAddress": "10.255.0.6",
		"IPPrefixLen": 16,
		"IPv6Gateway": "",
		"GlobalIPv6Address": "",
		"GlobalIPv6PrefixLen": 0,
		"MacAddress": "02:42:0a:ff:00:06",
		"DriverOpts": null
	}
}

Thank you in advance, any advice will be usefull.

[sscaling]

I'm a little bit confused. If you are using the docker-compose-swarm.yml file, why does Zookeeper have two virtual IPs? there should only be one instance.

Have you performed any diagnostics? i.e. from the kafka container telnet / netcat to the zookeeper node + port? Try connecting to the zookeeper node from an external client other than kafka? etc.

[csifinos]

Hello sscaling,

You have right that only one zookeeper instance is running, sorry if I am confused you. I have tried it again in another machine (Linux OS, not in windows as the previous attempt) and it works fine. So I believe that something I have messed up in the docker network.

I appreciate your help.

[sscaling]

np. Thanks for closing the loop.