Cron服务不是以Docker容器开头 [英] Cron service not starting with docker container

问题描述

我一直在尝试在docker容器中运行cron作业，并且在容器启动时似乎无法使cron服务运行.我可以远程进入正在运行的容器并运行"cron"以使服务启动而不会出现问题.我已经将此文件包含在我的DockerFile中，为什么命令没有被执行?

I have been trying to run a cron job within my docker container and I can't seem to get the cron service to run when the container is started. I can remote into the running container and run "cron" to get the service to start without issues. I have this included in my DockerFile, why is the command not being executed?

我可以通过执行以下操作(如上所述)使其正常工作:

I am able to get it to work by doing the following (as described above):

docker-compose build
docker-compose up -d
docker exec -it my_container /bin/bash
root@2348723ae34: /etc/init.d/cron status <--check cron service status
[FAIL] cron is not running ... failed!  <--- cron not running
root@2348723ae34: cron
[ ok ] cron is running. <-- simply running cron starts the service

crontab文件

*/2 * * * * rm -rf /usr/src/app/assets/aligned_output/* && rm -rf /usr/src/app/assets/aligned_input/*

DockerFile

FROM node:latest

RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
COPY . /usr/src/app

RUN apt-get update && apt-get -y install cron

# Add crontab file in the cron directory
ADD crontab /etc/cron.d/hello-cron

# Give execution rights on the cron job
RUN chmod 0644 /etc/cron.d/hello-cron

# Apply cron job
RUN crontab /etc/cron.d/hello-cron

# Create the log file to be able to run tail
RUN touch /var/log/cron.log

# Run the command on container startup
CMD cron && tail -f /var/log/cron.log

RUN touch /etc/crontab /etc/cron.*/*

EXPOSE 80
RUN npm install
CMD ["npm", "start"]

docker-compose.yml

inventory:
   build: .
   restart: always
   command: npm start
   ports:
   - "80:80"
   environment:
      - NODE_ENV=production

推荐答案

默认情况下，docker将在 CMD 进程上运行.一种技巧是，添加一个将在后台运行cron的 entrypoint 脚本，然后调用 CMD 节点应用程序.但是我更喜欢运行两个容器，一个用于CRON，另一个用于应用程序，这将有助于分离出冷杉容器.一个容器将以 CMD 的身份运行 cron 和其他运行节点应用程序.

By default, docker will run onlt the CMD process. One hack is, add one entrypoint script that will run cron in background and then invoke CMD node application. But I will prefer running two containers, one for CRON and other for application that will help in separating out concerns fir containers. One container will run cron as CMD and other run node application.

如果要共享使用卷挂载可能的文件系统.

In case you want to share filesystem that is possible using volume mounts.

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