[ISSUE #202 #159]when the broker uses hostNetwork, the IP registered by the broker to the nameserver is not the podIP

[usernameisnull]

when the broker uses hostNetwork, the IP registered by the broker to the nameserver is not the podIP
related #202 #159

What is the purpose of the change

when the broker uses hostNetwork, the broker's IP returned by NameServer is the IP of the k8s node where the broker is located.

This is because the broker uses the cluster ip（or other ip） instead of its own pod ip when registering.

The root cause is that when using hostnetwork, the host's network is used, including /etc/hosts. When generating the brokerIP1 configuration project, use the hostname -i command in the images/broker/alpine/brokerGenConfig.sh to obtain the ip.

/images/broker/alpine/brokerGenConfig.sh#L30

echo "brokerIP1=`hostname -i`" >> $BROKER_CONFIG_FILE

but in many cases this command does not correctly obtain the correct ip.
for exampels:

#/etc/hosts
127.0.0.1 localhost
127.0.1.1 master01

bash-4.4# hostname -i
127.0.1.1

when use 127.0.1.1 to register, the nameserver will select the IP based on its own algorithm. Most of the time it is not the status.podIP of the pod we want: https://github.com/apache/rocketmq/blob/2c898c9b31bf195174cf1e3a626a7c61f7576381/common/src/main/java/org/apache/rocketmq/common/utils/NetworkUtil.java#L91

#/etc/hosts
127.0.0.1 localhost
127.0.1.1 master01
10.6.178.178 master01

bash-4.4# hostname -i
127.0.1.1 10.6.178.178

check the log, it seems to be successful

but when we used the mqadmin command to check the registered broker address, we found that this was not the case.

Brief changelog

When setting up with hostNetwork option, we explicitly add an environment variable HOST_NETWORK_POD_IP on the pod. When obtaining brokerIP1, we obtain it from this environment variable and register it with the nameserver.

Verifying this change

the log from the pod:

the podIP:

use mqadmin see the broker address:

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[usernameisnull]

PTAL @caigy

[shangjin92]

BROKER_NETWORK_DEV=`/sbin/route |awk '/^default/{print $NF}'`
BROKER_IP=`ip a s ${BROKER_NETWORK_DEV} |awk -F' +|/' '/ inet /{print $3}'`
echo "brokerIP1=${BROKER_IP}" >> $BROKER_CONFIG_FILE

You can try this instead, that doesn't require manual IP specification, it works for me.

[usernameisnull]

BROKER_NETWORK_DEV=`/sbin/route |awk '/^default/{print $NF}'`
BROKER_IP=`ip a s ${BROKER_NETWORK_DEV} |awk -F' +|/' '/ inet /{print $3}'`
echo "brokerIP1=${BROKER_IP}" >> $BROKER_CONFIG_FILE

You can try this instead, that doesn't require manual IP specification, it works for me.

thank you, I will try this

[caigy]

IMO status.podIP can achieve it, so are there any reasons to get the pod ip by a complicated command?

[usernameisnull]

PTAL @caigy

[caigy]

LGTM