CentOS7でucarpを使いHA環境構築 (corosync2+pacemakerより簡単)

参考

• 公式サイト
• README
• UCARP on arch linux | Ramblings of a mad geek
• [NetBSD]CARPによるサーバ冗長化 - La vie des marmotte
• carpについてはCommon Address Redundancy Protocol - Wikipedia

参考その2

• 第3の冗長化プロトコル、CARPを試す : 負け組アーキテクトの憂鬱
• Linux-HA Japan Pacemakerリポジトリパッケージ (RHEL7) (1.1.13-1.1)

ソースからインストールする場合

ビルド

インストール

yum install -y libpcap-devel gcc
cd /opt
wget http://download.pureftpd.org/pub/ucarp/ucarp-1.5.2.tar.gz
tar xzf ucarp-1.5.2.tar.gz
cd ucarp-1.5.2
./configure && make && make install
mkdir /etc/ucarp/

スクリプト作成

/etc/ucarp/ucarp.sh

#!/bin/bash

UCARP=/usr/local/sbin/ucarp
UP=/etc/ucarp/up.sh
DOWN=/etc/ucarp/down.sh
DEV=enp0s3

# このサーバの実IP
SIP=192.168.100.11
#Virtual host ID number, every ucarp instance should have its own.
VHID=5
# 仮想IP
VIP=192.168.100.10
#The ucarp password shared only with the matching ucarp instance on another host
PASSWD="ucarp_pass1"
#any other flags you want to pass (refer to the man page for desired operation)
FLAGS="--shutdown --preempt --advskew=1"

#exec ucarp
exec ${UCARP} -i ${DEV} -s ${SIP} -v ${VHID} -p ${PASSWD} -a ${VIP} -u ${UP} -d ${DOWN} ${FLAGS}

/etc/ucarp/up.sh

#!/bin/bash

#the device and IP are passed by the ucarp daemon as $1 and $2 respectively
DEV="${1}"
IP="${2}"

/sbin/ip address add ${IP}/24 dev ${DEV}
/sbin/ip neigh flush dev ${DEV}

#start any service you need listening on your virtual IP
/bin/systemctl restart mysqld

/etc/ucarp/down.sh

#!/bin/bash

DEV="${1}"
IP="${2}"

/sbin/ip addr del ${IP}/24 dev ${DEV}

#optionally stop services here

/usr/lib/systemd/system/ucarp.service

Description=UCARP daemon
After=network.target

[Service]
ExecStart=/etc/ucarp/ucarp.sh
ExecStop=/bin/kill -TERM $MAINPID
KillMode=process
Restart=always

[Install]
WantedBy=multi-user.target

権限修正

chown root:root /etc/ucarp/*.sh
chmod 0700 /etc/ucarp/*.sh

サービス登録

サービス登録

systemctl enable ucarp
systemctl start ucarp

パッケージからインストールする場合

yum install -y ucarp

# rpm -qal ucarp
/etc/ucarp
/etc/ucarp/vip-001.conf.example
/etc/ucarp/vip-common.conf
/usr/lib/systemd/system/ucarp@.service
/usr/libexec/ucarp
/usr/libexec/ucarp/ucarp
/usr/libexec/ucarp/vip-down
/usr/libexec/ucarp/vip-up
/usr/sbin/ucarp
/usr/share/doc/ucarp-1.5.2
/usr/share/doc/ucarp-1.5.2/AUTHORS
/usr/share/doc/ucarp-1.5.2/COPYING
/usr/share/doc/ucarp-1.5.2/ChangeLog
/usr/share/doc/ucarp-1.5.2/NEWS
/usr/share/doc/ucarp-1.5.2/README
/usr/share/locale/en@boldquot/LC_MESSAGES/ucarp.mo
/usr/share/locale/en@quot/LC_MESSAGES/ucarp.mo

設定

/etc/ucarp/vip-up

#!/bin/sh
exec 2>/dev/null

/sbin/ip address add "$2"/24 dev "$1"

echo "up" `date "+%c"` \
 | mail -s `hostname`" vip001 up" root@localhost

/etc/ucarp/vip-down

#!/bin/sh
exec 2>/dev/null

/sbin/ip address del "$2"/24 dev "$1"

echo "down" `date "+%c"` \
 | mail -s `hostname`" vip001 down" root@localhost

/etc/ucarp/vip-common.conf

PASSWORD="hogehoge"
BIND_INTERFACE="eth1"
SOURCE_ADDRESS="192.168.100.11"
OPTIONS="--shutdown --preempt"

/etc/ucarp/vip-001.conf

UPSCRIPT=/etc/ucarp/vip-up
DOWNSCRIPT=/etc/ucarp/vip-down
VIP_ADDRESS="192.168.100.10"

サービス登録

サービス登録

systemctl enable ucarp@vip-001
systemctl start ucarp@vip-001

参考: Full Text Bug Listing