can not output to kafka when logstash runs in docker

[cgyim]

Hi,

• Version: 5.5.1
• Operating System: centos ,Linux es-logger-kibana 3.10.0-327.18.2.el7.x86_64 #1 SMP Thu May 12 11:03:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
• Config File (if you have sensitive info, please remove it):
  logstash config:
  input {
file{
path => "/var/log/dpkg.log"
start_position => "beginning"
sincedb_path => "/dev/null"
tags => ["test"]
# codec => plain {
# charset => "GB2312"
# }
}
}
output {
kafka {
# message_key => "hangqing"
topic_id => "you2"
bootstrap_servers => "10.88.115.20:9092,10.88.115.20:9093,10.88.115.20:9094"
codec => plain {
format => "%{message}"
}
}
# stdout { codec => rubydebug}
}
  docker-compose config:
  logstash:
image: logstash:5.5.1
net: host
volumes:
- /opt/docker-compose/logstash/logstash.conf:/etc/logstash/conf.d/logstash.conf
- /opt/docker-compose/logstash/jvm.options:/etc/logstash/jvm.options
user: root
command: logstash --debug -f /etc/logstash/conf.d/logstash.conf
• Steps to Reproduce:

1. docker-compose up logstash
2. (another terminal in kafka home)bin/kafka-console-consumer.sh --bootstrap-server 0.0.0.0:9092 --topic you2 --zookeeper 0.0.0.0:2181 --from-beginning .
3. no output , but the topic was created. It's was wierd.

I am sure that the kafka works fine because when logstash runs directly in os as a service, everything works fine , i can see the output typing the same command as a kafka consumer.
iptables config:
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpts:3000:9999
ACCEPT 112 -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22

Chain FORWARD (policy ACCEPT)
target prot opt source destination
DOCKER-ISOLATION all -- 0.0.0.0/0 0.0.0.0/0
DOCKER all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpts:3000:65535
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpts:3000:65535

Chain DOCKER (1 references)
target prot opt source destination
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpts:3000:65535
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpts:3000:65535

Chain DOCKER-ISOLATION (1 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Could some1 give me a hand :( ?

[cgyim]

logstash-kafka.txt

logstash debug output log file also provided