linux – Elastic Beanstalk日志轮换导致Apache重启

再生产

我们创建最简单的Python WSGI应用程序.

application.py

import time


def application(environ,start_responsE):
    # somewhat realistic response duration
    time.sleep(0.5)

    status = '200 OK'
    response_headers = [('Content-type','text/plain')]
    start_response(status,response_headers)
    return [b'Hello World!\n']

将其压缩到application.zip.然后创建Elastic Beanstalk Python应用程序和环境,上传档案.确保使用您拥有的密钥对.保留其他设置默认值.等到它完成(几分钟).

ssh到底层的EC2实例中(参见EB日志中的实例标识符).输入(httpd的logrotate post-action,见下文)：

sudo /sbin/service httpd reload

然后在你的机器上运行：

siege -v -b -c 10 -t 10S http://your-test-eb.you-aws-region.elasticbeanstalk.com/

当它运行时,重复重载命令几次.

然后你会看到如下内容：

** SIEGE 3.0.8
** Preparing 10 concurrent users for battle.
The server is Now under siege...
http/1.1 200   0.63 secs:      13 bytes ==> GET  /
http/1.1 200   0.65 secs:      13 bytes ==> GET  /
http/1.1 200   0.64 secs:      13 bytes ==> GET  /
http/1.1 200   0.60 secs:      13 bytes ==> GET  /
...

这是重装时会发生什么.

http/1.1 504   0.06 secs:       0 bytes ==> GET  /
http/1.1 504   0.07 secs:       0 bytes ==> GET  /
http/1.1 504   0.08 secs:       0 bytes ==> GET  /
http/1.1 504   0.10 secs:       0 bytes ==> GET  /
http/1.1 504   0.11 secs:       0 bytes ==> GET  /
http/1.1 504   0.66 secs:       0 bytes ==> GET  /
http/1.1 504   0.19 secs:       0 bytes ==> GET  /
http/1.1 504   0.20 secs:       0 bytes ==> GET  /
http/1.1 504   0.09 secs:       0 bytes ==> GET  /

然后它恢复了.

http/1.1 200   1.25 secs:      13 bytes ==> GET  /
http/1.1 200   1.24 secs:      13 bytes ==> GET  /
http/1.1 200   1.26 secs:      13 bytes ==> GET  /
...

LifTing the server siege..      done.

transactions:                 75 hits
Availability:              81.52 %
Elapsed time:               9.40 secs
Data transferred:           0.00 MB
Response time:              1.21 secs
transaction rate:           7.98 trans/sec
Throughput:             0.00 MB/sec
Concurrency:                9.68
successful transactions:      75
Failed transactions:          17
Longest transaction:        4.27
Shortest transaction:       0.06

请注意,ELB似乎对问题没有任何影响,并且可以通过两个SSH会话复制到底层EC2并且(Amazon AMI没有围攻)：

ab -v 4 -c 10 -t 10 http://your-test-eb.you-aws-region.elasticbeanstalk.com/

原因

/etc/cron.hourly/cron.logrotate.elasticbeanstalk.httpd.conf

#!/bin/sh
test -x /usr/sbin/logrotate || exit 0
/usr/sbin/logrotate /etc/logrotate.elasticbeanstalk.hourly/logrotate.elasticbeanstalk.httpd.conf

/etc/logrotate.elasticbeanstalk.hourly/logrotate.elasticbeanstalk.httpd.conf

/var/log/httpd/* {
size 10M
missingok
notifempty
rotate 5
sharedscripts
compress
dateext
dateformat -%s
create
postrotate
    /sbin/service httpd reload > /dev/null 2>/dev/null || true
endscript
olddir /var/log/httpd/rotated
}

请注意postrotate. / sbin / service只是/etc/init.d/中脚本的System V包装器.它的手册页说：

请注意,重新加载不是标准的Apache maintenance command.这是发行版的下游添加.让我们看一下init脚本/etc/init.d/httpd.相关部分如下：

reload() {
        echo -n $"Reloading $prog: "
        @R_673_10943@k13 || exit 1
        killproc -p ${pidfilE} $httpd -HUP
        RETVAL=$?
        echo
}

如您所见,它向Apache发送HUP信号,解释为Restart Now：

TERM很好地解释了504s.但它可能应该如何完成是Graceful Restart,因为它也重新打开日志但不终止正在提供的请求：

解决方法

可以使用.ebextensions替换/etc/logrotate.elasticbeanstalk.hourly/logrotate.elasticbeanstalk.httpd.conf.在根目录中创建
.ebextensions / 10_logs.config包含以下内容(基本上将“reload”替换为“graceful”)：

files:
    "/etc/logrotate.elasticbeanstalk.hourly/logrotate.elasticbeanstalk.httpd.conf":
        mode: "000644"
        owner: root
        group: root
        content: |
            /var/log/httpd/* {
                size 10M
                missingok
                notifempty
                rotate 5
                sharedscripts
                compress
                dateext
                dateformat -%s
                create
                postrotate
                    /sbin/service httpd graceful > /dev/null 2>/dev/null || true
                endscript
                olddir /var/log/httpd/rotated
            }

并重新部署您的Elastic Beanstalk环境.请注意,然而随后的亚秒优雅重启,我能够(零星地)产生503服务不可用,但是,对于日志轮换不是这样,因为均匀间隔的优雅重启没有错误.