如何利用shell开发keepalived启动脚本

当使用keepalived作为高可用性解决方案时，启动脚本是非常重要的。启动脚本的正确编写可以确保keepalived的稳定工作。

本文将介绍如何使用shell编写keepalived启动脚本的完整攻略。这个过程需要在Linux环境下进行，以下是需要的步骤：

步骤1：确认文件权限

在编写脚本之前，需要确认keepalived的安装路径以及启动脚本的文件权限。一般情况下，keepalived的安装路径在/usr/local/keepalived，启动脚本的文件权限应该为755。

步骤2：编写启动脚本

接下来需要编写启动脚本，脚本的目的是确保keepalived可以顺利启动并且实现高可用性。

示例1：在keepalived节点启动

在这个示例中，假设你的系统有两个节点：node1和node2。只有在node1无法正常工作时，node2才会启动keepalived。此时，node2需要检查node1的状态并将虚拟IP地址绑定到自己上。

#!/bin/bash

VIP=10.0.0.1
NETMASK=255.255.255.0
INTERFACE=eth0
STATE=/var/run/keepalived.state

case "$1" in
    start)
        if [ -f $STATE ] && [ "$(cat $STATE)" = "MASTER" ]; then
            echo "keepalived is already running"
            exit 1
        fi
        if [ "$(cat /sys/class/net/$INTERFACE/carrier)" = "0" ]; then
            echo "network not ready"
            exit 1
        fi
        echo "starting keepalived"
        echo "BACKUP" > $STATE
        /usr/local/keepalived/sbin/keepalived -D -n -f /etc/keepalived/keepalived.conf
        ;;
    stop)
        echo "stopping keepalived"
        pkill keepalived
        ;;
    status)
        if [ -f $STATE ] && [ "$(cat $STATE)" = "MASTER" ]; then
            echo "keepalived is running as MASTER"
        elif [ -f $STATE ] && [ "$(cat $STATE)" = "BACKUP" ]; then
            echo "keepalived is running as BACKUP"
        else
            echo "keepalived is not running"
        fi
        ;;
    *)
        echo "usage: $0 start|stop|status"
        ;;
esac

示例2：在万兆交换机启动

如果您的系统支持万兆交换机，则可以使用以下脚本来编写启动脚本。这里的脚本将路由绑定到万兆交换机上，因此即使在物理节点故障的情况下，也可以始终保持虚拟IP地址处于活动状态。

#!/bin/bash

VIP=10.0.0.1
NETMASK=255.255.255.0
INTERFACE=eth0
MASTER_IP=10.0.0.10
SLAVE_IP=10.0.0.11

case "$1" in
    start)
        echo "starting keepalived"
        /usr/local/keepalived/sbin/keepalived -D -n -f /etc/keepalived/keepalived.conf
        ;;
    stop)
        echo "stopping keepalived"
        pkill keepalived
        ;;
    status)
        if [[ "$(ip addr show dev ${INTERFACE}|grep "scope global" >/dev/null 2>&1; echo $?)" -eq "0" ]]; then
            echo "keepalived is running as MASTER"
        else
            echo "keepalived is running as BACKUP"
        fi
        ;;
    *)
        echo "usage: $0 start|stop|status"
        ;;
esac

步骤3：配置keepalived.conf

启动脚本是keepalived的一个部分。启动脚本将自定义选项定义，并且keepalived.conf文件将配置其他选项，例如节点的优先级，虚拟IP地址等。

下面是一个简单的keepalived.conf文件示例：

global_defs {
  router_id keepalived_node1
}

vrrp_script check_nginx {
  script "/usr/local/bin/check_nginx.sh"
  interval 2
}

vrrp_instance VI_1 {
  state BACKUP
  interface eth0
  virtual_router_id 51
  priority 100
  advert_int 1
  authentication {
    auth_type PASS
    auth_pass
  }
  track_script {
    check_nginx
  }
  virtual_ipaddress {
    192.168.100.100
  }
}