bash - Docker: Cronjob is not working

Question

I am trying to run cron job on Docker container. I have a running container (Fedora 20). I have also installed cron packages in container and explicitly run the cron daemon. I have also checked cron.deny file it is empty and there is no file called cron.allow under /etc/ directory.

Whenever I tried to set the cronjob by using crontab -e or trying to list the cron job using 

    crontab -l I am getting following error.

bash-4.2# crontab -l
You (root) are not allowed to access to (crontab) because of pam configuration.


bash-4.2# crontab -e
You (root) are not allowed to access to (crontab) because of pam configuration.

I also checked the /etc/pam.d/crond file it has following entry

bash-4.2# vi /etc/pam.d/crond

#
# The PAM configuration file for the cron daemon
#
#
# No PAM authentication called, auth modules not needed

account    required   pam_access.so
account    include    password-auth
session    required   pam_loginuid.so
session    include    password-auth
auth       include    password-auth

Has any one faced this issue? If yes could you please suggest me some pointer on this?

thanks in advance.

Answer 1

An LXC container is not a virtual machine. You'll need to explictly run the cron daemon in the foreground. Better still run cron from program like Supervisor or runit.

Reference: Docker documentation

Traditionally a Docker container runs a single process when it is launched, for example an Apache daemon or a SSH server daemon. Often though you want to run more than one process in a container. There are a number of ways you can achieve this ranging from using a simple Bash script as the value of your container's CMD instruction to installing a process management tool.

In this example we're going to make use of the process management tool, Supervisor, to manage multiple processes in our container. Using Supervisor allows us to better control, manage, and restart the processes we want to run. To demonstrate this we're going to install and manage both an SSH daemon and an Apache daemon.