使用 cron、bash 和 wget 监控 Web 服务器的状态
我最近需要一个真正真正简单的远程监控工具，用来跟踪服务器的可用性，我不需要记录运行时间以及其他别的信息，只是想知道服务器有没有异常挂机之类的。没找到这样的工具，我只好自己写一个。尽管有很多这样的工具，而且都是开源免费的，例如 Nagios、Cacti 等等，但这些都太重了。我不需要那么复杂的，下面是我的基本需求列表：[*]要求是 bash, wget, 以及 “mail” 命令 (sendmail, exim, postfix, 之类)
[*]可监控任何 HTTP/HTTPS URL, 检查 “200″ 状态返回
[*]检查请求返回时间，用于监控一些慢响应
[*]通过 Email 发送异常状态提醒
[*]可定制的接收异常信息的邮箱
[*]可定制慢响应的时间
[*]避免重复发送相同的异常提醒
[*]使用简单文本文件作为数据存储，不需要数据库
这些都非常的基本，但很有效。
简单的 crontab 作业定义*/5 * * * * root /home/username/sitemonitor.sh
sitemonitor.sh 脚本源码
#!/bin/bash
# Simple HTTP/S availability notifications script v0.1
# March 20, 2012 by Jeff Rowberg - http://www.sectorfej.net
HOSTS=( \
"http://www.yahoo.com" \
"https://www.google.com" \
"http://www.amazon.com" \
)
NOTIFY_FROM_EMAIL="Site Monitoring <monitoring@example.com>"
NOTIFY_TO_EMAIL="Server Admin <admin@example.com>"
STATUS_FILE="/home/username/sitemonitor.status"
SLOW_THRESHOLD=10
OK_STATUSES=( "200" )
################################################################
# NO MORE USERMOD STUFF BELOW THIS, MOST LIKELY #
################################################################
# thanks to stackoverflow!
# stackoverflow.com/questions/3685970/bash-check-if-an-array-contains-a-value
function contains() {
local n=$#
28
local value=${!n}
for ((i=1; i < $#; i++)) {
if [ "${!i}" == "${value}" ]; then
echo "y"
return 0
fi
}
echo "n"
return 1
}
rm -f /tmp/sitemonitor.status.tmp
for HOST in "${HOSTS[@]}"
do
START=$(date +%s)
RESPONSE=`wget $HOST --no-check-certificate -S -q -O - 2>&1 | \
awk '/^HTTP/{print \$2}'`
END=$(date +%s)
DIFF=$(( $END - $START ))
if [ -z "$RESPONSE" ]; then
RESPONSE="0"
fi
if [ $(contains "${OK_STATUSES[@]}" "$RESPONSE") == "y" ]; then
if [ "$DIFF" -lt "$SLOW_THRESHOLD" ]; then
STATUS="UP"
else
STATUS="SLOW"
fi
else
STATUS="DOWN"
fi
touch $STATUS_FILE
STATUS_LINE=`grep $HOST $STATUS_FILE`
STATUS_PARTS=($(echo $STATUS_LINE | tr " " "\n"))
CHANGED=${STATUS_PARTS}
if [ "$STATUS" != "${STATUS_PARTS}" ]; then
#if [ -e "${STATUS_PARTS}" ] || [ "$STATUS" != "UP" ]; then
if [ -z "${STATUS_PARTS}" ]; then
STATUS_PARTS="No record"
fi
TIME=`date -d @$END`
echo "Time: $TIME" > /tmp/sitemonitor.email.tmp
echo "Host: $HOST" >> /tmp/sitemonitor.email.tmp
echo "Status: $STATUS" >> /tmp/sitemonitor.email.tmp
echo "Latency: $DIFF sec" >> /tmp/sitemonitor.email.tmp
echo "Previous status: ${STATUS_PARTS}" >> /tmp/sitemonitor.email.tmp
if [ -z "${STATUS_PARTS}" ]; then
TIME="No record"
else
TIME=`date -d @${STATUS_PARTS}`
fi
echo "Previous change: $TIME" >> /tmp/sitemonitor.email.tmp
`mail -a "From: $NOTIFY_FROM_EMAIL" \
-s "SiteMonitor Notification: $HOST is $STATUS" \
"$NOTIFY_TO_EMAIL" < /tmp/sitemonitor.email.tmp`
rm -f /tmp/sitemonitor.email.tmp
#else
# first report, but host is up, so no need to notify
#fi
CHANGED="$END"
fi
echo $HOST $RESPONSE $CHANGED $END $DIFF $STATUS >> /tmp/sitemonitor.status.tmp
done
mv /tmp/sitemonitor.status.tmp $STATUS_FILE
异常提醒邮件的示例
view sourceprint?
Time: Fri Mar 23 17:20:02 UTC 2012
Host: http://www.example.com
Status: UP
Latency: 0 sec
Previous status: DOWN
Previous change: Fri Mar 23 15:05:20 UTC 2012
相当的简单，但工作的很好，你可以试试。
英文原文，OSCHINA原创翻译来自：http://www.oschina.net/question/12_45835
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