HDFS HA failover script

hi,

Assuming that you have HDFS HA enabled, then you can have it done. Compiling small HDFS utility to do the failover by handy. Enjoy... :)

#!/bin/bash

SUHDFS="sudo -u hdfs hdfs"

nameservice=`$SUHDFS getconf -confKey dfs.nameservices`

echo "Nameservice: $nameservice"

serviceIds=`$SUHDFS getconf -confKey dfs.ha.namenodes.$nameservice | sed -s 's|,| |g'`
state=""
is_active=""
is_standby=""
for Id in `echo $serviceIds`
do
        namenode_hostname=`$SUHDFS getconf -confKey dfs.namenode.rpc-address.$nameservice.$Id`
        state=`$SUHDFS haadmin -getServiceState $Id`
        if [ "$state" == "active" ]
        then
                is_active="$Id"
        fi
        if [ "$state" == "standby" ]
        then
                is_standby="$Id"
        fi

        echo "Hostname : $namenode_hostname"
        echo "Service ID: $Id ($state)"
done

echo ""
echo -n "Do you want to do a failover from $is_active (active) -> $is_standby (standby)?: [y/n]"
read ans

if [ "$ans" = "y" ]
then
        echo " >> failing over now ...."
        echo " Executing >>hdfs haadmin -failover $is_active $is_standby"
        $SUHDFS haadmin -failover $is_active $is_standby
        if [ "$?" == "0" ]
        then
                echo " >> Done"
        else
                echo " >> Failed"
        fi
else
        echo ">> Exitting ..."
fi

Here is the result.

[root@ip-172-31-17-185 ~]# ./haadmin.sh
Nameservice: nameservice1
Hostname : ip-172-31-17-183.ap-southeast-1.compute.internal:8020
Service ID: namenode22 (standby)
Hostname : ip-172-31-17-184.ap-southeast-1.compute.internal:8020
Service ID: namenode37 (active)

Do you want to do a failover from namenode37 (active) -> namenode22 (standby)?: [y/n]y
 >> failing over now ....
 Executing >>hdfs haadmin -failover namenode37 namenode22
Failover to NameNode at ip-172-31-17-183.ap-southeast-1.compute.internal/172.31.17.183:8022 successful
 >> Done
[root@ip-172-31-17-185 ~]# ./haadmin.sh
Nameservice: nameservice1
Hostname : ip-172-31-17-183.ap-southeast-1.compute.internal:8020
Service ID: namenode22 (active)
Hostname : ip-172-31-17-184.ap-southeast-1.compute.internal:8020
Service ID: namenode37 (standby)

Do you want to do a failover from namenode22 (active) -> namenode37 (standby)?: [y/n]n
>> Exitting ...