Cron 和 Crontab 文件未在 Docker 中执行 [英] Cron and Crontab files not executed in Docker
问题描述
我有这个简单的 Dockerfile 用于测试，但这在我的 LEMP 堆栈中的 PHP 映像中也是相同的:cron 作业根本没有在 Docker 中执行.
I have this simple Dockerfile for testing, but this is also same in my LEMP stack in a PHP image: cron jobs simply not being executed in Docker.
这是我的测试 Dockerfile:
This is my testing Dockerfile:
FROM debian:latest
MAINTAINER XY <info@domain.com>
LABEL Description="Cron" Vendor="Istvan Lantos" Version="1.0"
RUN apt-get -y update && apt-get -y dist-upgrade
&& apt-get -y install
cron
rsyslog
vim
RUN rm -rf /var/lib/apt/lists/*
#cron fixes
RUN touch /etc/crontab /etc/cron.d/* /var/spool/cron/crontabs/*
#COPY etc/cron.d /etc/cron.d
COPY etc/crontab /etc/crontab
#COPY var/spool/cron/crontabs /var/spool/cron/crontabs
RUN chmod 600 /etc/crontab /etc/cron.d/* /var/spool/cron/crontabs/*
RUN touch /etc/crontab /etc/cron.d/* /var/spool/cron/crontabs/*
RUN rm -rf /var/lib/apt/lists/*
COPY docker-entrypoint.sh /
RUN chmod +x /docker-entrypoint.sh
CMD ["/docker-entrypoint.sh"]
docker-entrypoint.sh:
docker-entrypoint.sh:
#!/bin/bash
set -e
echo PID1 > /dev/null
/etc/init.d/rsyslog start
#Stay in foreground mode, don’t daemonize.
/usr/sbin/cron -f
这是 Crontab 文件.我还在 /etc/cron.d 或 /var/spool/cron/crontabs 中放置了一个带有用户名的衬垫，但效果是一样的如果我修改了这个基本 crontab 文件:不会执行 cron 作业:
And this is the Crontab file. I also placed one liners in /etc/cron.d or /var/spool/cron/crontabs with the name of the user, but the effect was the same just like if I modified this base crontab file: cron jobs not will be executed:
MAILTO=""
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.
SHELL=/bin/sh
#PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/php7/bin:/usr/local/php7/sbin
# m h dom mon dow user command
#17 * * * * root cd / && run-parts --report /etc/cron.hourly
#25 6 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
#47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
#52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
#
*/1 * * * * root date >> /var/log/cron-test.log 2>&1
这是 /var/log/syslog 文件的输出:
Jan 23 09:38:39 1ab854e8d9a7 rsyslogd: [origin software="rsyslogd" swVersion="8.4.2" x-pid="14" x-info="http://www.rsyslog.com"] start
Jan 23 09:38:39 1ab854e8d9a7 rsyslogd: imklog: cannot open kernel log(/proc/kmsg): Operation not permitted.
Jan 23 09:38:39 1ab854e8d9a7 rsyslogd-2145: activation of module imklog failed [try http://www.rsyslog.com/e/2145 ]
Jan 23 09:38:39 1ab854e8d9a7 cron[19]: (CRON) INFO (pidfile fd = 3)
Jan 23 09:38:39 1ab854e8d9a7 cron[19]: (*system*) NUMBER OF HARD LINKS > 1 (/etc/crontab)
Jan 23 09:38:39 1ab854e8d9a7 cron[19]: (*) ORPHAN (no passwd entry)
Jan 23 09:38:39 1ab854e8d9a7 cron[19]: (CRON) INFO (Running @reboot jobs)
/var/log/cron-test.log 不会由 cron 作业创建.
/var/log/cron-test.log won't be created by the cron job.
对于那些将其标记为离题"和超级用户材料的人，我有一个问题，而且这是关于通用计算硬件和软件的:真的吗?Docker 问题何时成为系统管理员?这样，这里的每个 Docker 相关问题都至少有一个标志.我并不反对将更多用户推广到鲜为人知的子网站，但与他们相比，我们有更多的变化可以在这里找到答案.
I have a question for those who flagged this as "off topic" and SuperUser material, plus this is about general computing HARDWARE AND SOFTWARE: really? Docker questions when become sysadmin stuff? This way every Docker related question here have at least one flag. I'm not against promoting more users to the less known child sites, but we have more change to get the answer here than their.
更新:
这是我想出的，直到 cron 作业不工作:
This is what I come up with until cron jobs not working:
Dockerfile 结束:
End of Dockerfile:
COPY cron-jobs.sh /
RUN chmod +x /cron-jobs.sh
COPY docker-entrypoint.sh /
RUN chmod +x /docker-entrypoint.sh
CMD ["/docker-entrypoint.sh"]
docker-entrypoint.sh:
docker-entrypoint.sh:
#!/bin/bash
set -e
echo PID1 > /dev/null
# Run script in the background (this is not daemonized)
/cron-jobs.sh &
/usr/local/php7/sbin/php-fpm --nodaemonize --fpm-config /usr/local/php7/etc/php-fpm.conf
cron-jobs.sh:
cron-jobs.sh:
#!/bin/bash
while true; do
date >> /var/log/cron-test.log 2>&1
sleep 60
done
推荐答案
Cron(至少在 Debian 中)不会执行超过 1 个硬链接的 crontab，请参阅 bug 647193.由于 Docker 使用覆盖，它导致文件的链接不止一个，因此您必须在启动脚本中 touch 它，因此链接被切断:
Cron (at least in Debian) does not execute crontabs with more than 1 hardlink, see bug 647193. As Docker uses overlays, it results with more than one link to the file, so you have to touch it in your startup script, so the link is severed:
touch /etc/crontab /etc/cron.*/*
这篇关于Cron 和 Crontab 文件未在 Docker 中执行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
