After using CentOS 7 image to create a container, you may encounter such a problem that you use systemctl to start the service and report an error. For this error report, let’s analyze it next!

# docker run -itd –name centos7 centos:7

# docker attach centos7

# yum install vsftpd

# systemctl start vsftpd

Failed to get D-Bus connection: Operation not permitted

The reasons are as follows:

The design concept of docker is that there is no background service running in the container. The container itself is an independent main process on the host, which can also be indirectly understood as the application process running the service in the container. The life cycle of a container exists around the main process, so the correct way to use the container is to run the services in the foreground.

When it comes to SYSTEMd, this suite has become the default service management for mainstream Linux distributions (such as centos7 and Ubuntu 14 +), replacing the traditional Systemv style service management. SYSTEMd maintains system services, which require privileges to access the Linux kernel. The container is not a complete operating system, there is only one file system, and the default startup is only for ordinary users to access the Linux kernel, that is, there is no privilege, so it can’t be used naturally!

Therefore, please follow the container design principles and run a foreground service in one container!!!

Yes, run the container in privileged mode.

The solution is as follows:

Create container:

# docker run -d -name centos7 –privileged=true centos:7 /usr/sbin/init

Enter container:

# docker exec -it centos7 /bin/bash

This allows you to start the service using systemctl