之前做过的一个网站又挂了，老师留言让我及时修复。一查看原来访问量过大，OutOfMemoryError了。于是想写一个脚本自动监测网站运行情况，不能访问时自动重启，这样我就省事了。

主要功能如下：

每隔一分钟访问一次首页2. 如果有数据返回，检查它是否包含某些关键字3. 如果有误，则检查数据库是否运行正常4. 再重启play

由于服务器的环境限制得很严格，不能访问其它网站，很多常用工具都没法下载，用bash来写比较麻烦。用java写的话，有点繁琐，而且修改起来也不方便，还要编译。最后决定用groovy，毕竟跟java比较接近好入手。

脚本如下：

!/usr/bin/env groovy

import java.net.*

// settings
INDEX_URL = “http://localhost:9001/login”
APP_ROOT = “/path/to/app/root”
SERVER_PID_FILE = APP_ROOT + '/server.pid'
PLAY_CMD = “play”
KEYWORDS = ['name=“password”']

println “Starting web monitor …”

// check every 1min
while (true) {

println ""      
println "&#8212;&#8212;&#8212;&#8212;&#8212; checking &#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;"      
println ""      
try {      
    if (readUrl()) {      
        println "Everything is fine"      
    } else {      
        println "There is something wrong"      
        restartDB()      
        restartPlay()      
    }      
} catch (Exception e) {      
    println "    exception: " + e.toString().take(40)      
}      
println "waiting for 1 min"      
Thread.sleep(1000 * 60);

}

boolean readUrl() {

println "Read data from ${INDEX_URL}"

def input = null;     
try {      
    URL url = new URL(INDEX_URL)      
    def conn = url.openConnection()      
    conn.setConnectTimeout(5 * 1000) // 5s      
    conn.setReadTimeout(5 * 1000) // 5s, important      
    conn.connect();

    input = conn.getInputStream()     
    def content = input.getText("UTF-8")

    println "    response has ${content.length()} chars"

    for(String keyword: KEYWORDS) {     
        if(content.contains(keyword)) {      
            println "    response contains keyword ${keyword}, valid"      
            return true      
        }      
    }      
    println "    response doesn't contain phone or email, invalid"      
} catch (Exception e) {      
    println "    exception: " + e.toString().take(40)      
    return false      
} finally {      
    if (input != null) {      
        input.close()      
    }      
}

}

def restartPlay() {

println "Check play"      
def pid = checkPlayIsRunning()      
println "    pid: ${pid}"

if (pid) {     
    println "    try to kill the play process: ${pid}"      
    execute("kill -9 ${pid}").waitFor()      
}

if (new File(SERVER_PID_FILE).isFile()) {     
    println "    delete: ${SERVER_PID_FILE}"      
    new File(SERVER_PID_FILE).delete()      
}

println "    start play ..."     
execute("${PLAY_CMD} start ${APP_ROOT} -%prod")

}

def restartDB() {

println "Check DB"      
println "    check pg_ctl status"      
def proc = execute("su - postgres -c 'pg_ctl status'")      
proc.waitFor()

def out = proc.in.text     
println "    response: ${out?.take(40)}"      
if (!out.contains("server is running")) {      
    println "    not running, pg_ctl start ..."      
    execute("ru - postgres -c 'pg_ctl start'")      
}

}

String checkPlayIsRunning() {

println "    check ps of play"      
def proc = execute("ps -eaf | grep play")      
proc.waitFor()

def line = proc.in.text.readLines().find { it.contains(APP_ROOT) }     
println "    matched line: ${line?.take(40)}"

return line?.split("\\s+")?.getAt(1)

}

def execute(String command) {

["sh", "-c", command].execute()

}

该脚本运行起来后，就可以24小时不间断地监测网站了，我再也不用担心在睡梦中接到老师的问候电话了。

对了别忘了先安装groovy，还要把该脚本设为可执行。

如果把该脚本设为开机自动启动，则服务器重启也不怕了。如何设置，可参考我另一个文章：如何让linux开机就运行某个groovy脚本

注意：上面的脚本已经修改，增强了read timeout，这个值非常重要。因为在运行时发现，如果网站卡住（可以连接，但不返回数据时），此脚本也会卡住。

(2012-11-21) 使用groovy写play程序的监控脚本

!/usr/bin/env groovy