How to solve the problem of Docker on CentOS

Troubleshooting and Resolving Guide for Docker in CentOS System

This article provides step-by-step guidance to help you diagnose and resolve common Docker problems in CentOS systems.

1. Verify Docker installation and version:

First, make sure Docker has correctly installed and run the compatible version. Check Docker version with the following command:

 docker version

If not installed, please use the following command to install:

 sudo yum install docker

2. Check Docker service status:

After the installation is complete, check whether the Docker service has started:

 systemctl status docker.service

If the service does not start or fails to start, please troubleshoot further based on the error message.

3. Analyze Docker logs:

When the Docker service starts, it is crucial to view the logs:

 tail -f /var/log/docker.log

Log information can reveal the root cause of the problem, such as missing dependencies, network connection errors, etc. Repair according to the log prompts.

4. Check Docker configuration file:

An incorrect Docker configuration file may also cause the service to fail to start. In CentOS 7 systems, the configuration file is usually located in /etc/sysconfig/docker . Edit the configuration file using the following command:

 vi /etc/sysconfig/docker

Carefully check the configuration, especially the proxy settings and storage paths, save and restart the Docker service after fixing the error.

5. Clean the Docker cache and restart the service:

If the above method is invalid, try cleaning the Docker cache and restarting the service:

 sudo systemctl stop docker.service
sudo rm -rf /var/lib/docker/*
sudo systemctl start docker.service

This step clears potential cache issues and reinitializes the Docker configuration. The problem still exists, and it is recommended to seek professional technical support.

6. Solve SELinux permissions issues:

If the directory mounted with -v is not available in the container and a Permission denied error is prompted, it may be a SELinux rule conflict. Solutions include: add --privileged=true parameter in docker run command, disable SELinux, or adjust SELinux rules.

7. Handle firewall issues:

Docker startup exceptions may be related to firewalld. Try temporarily shutting down the firewall:

 sudo systemctl stop firewalld
sudo systemctl restart docker

If the problem still exists, you need to check the interactive configuration between Docker and firewalld/iptables.

8. Handle kernel errors:

Kernel errors may also cause Docker to fail to start. View the system log for detailed error information and repair or upgrade the kernel based on the error information.

If the problem persists, please refer to the official Docker documentation or seek community help.

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