What to do if centeros docker installation error occurs

CentOS Docker installation error

With the rapid development and widespread application of container technology, Docker has become one of the most popular containerization solutions. However, you may encounter various strange errors and issues when installing Docker on CentOS.

This article summarizes some common error messages during the CentOS Docker installation process and the corresponding solutions. I hope it can bring some help to readers who encounter problems.

Question 1: When starting Docker, the error "Failed to start docker.service: Unit not found"

This error occurs on CentOS 7 and above. Since Docker relies on the Systemd service manager, the docker.service file is called when starting the Docker service. If this file does not exist in the system or the file path is incorrect, the above error will occur.

Solution:

Execute the following command in the terminal to check whether docker.service exists in the correct path:

ls /usr/lib/systemd/system/docker.service

If the file does not exist, you need to reinstall Docker. If the file exists but the path is incorrect, you can try the following command to modify the path:

sudo systemctl edit docker.service

Then add the following content to the new editor:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H fd://

Save and close the editor, then restart Docker Service:

sudo systemctl daemon-reload
sudo systemctl restart docker

Question 2: When using yum to install Docker, the error "Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again"

This error usually occurs in CentOS 7 and above versions. It indicates that the system cannot download the default Docker dependency package, usually due to network issues or source configuration issues.

Solution:

Confirm that the network connection is normal. If the network is normal but the download still fails, you can try to update the yum package manager and reinstall Docker:

sudo yum clean all
sudo yum update
sudo yum install docker

Question 3: When using yum to install Docker, an error occurs "Error: Package: docker-ce-- 3.el7.x86_64 (docker-ce-stable) Requires: container-selinux >= 2.9”

This error usually occurs when installing the latest version of Docker (such as Docker CE 17.06.0.ce).

Solution:

Since the new version of Docker needs to update the container-selinux package, and the default container security extension version of CentOS is too low, you need to manually install the updated version of container-selinux.

First confirm that the epel-release extension source has been installed in the system:

sudo yum install epel-release

Then install the updated version of container-selinux:

sudo yum install -y container-selinux

Now reinstall Docker:

sudo yum install docker

Question 4: When starting Docker, the error "docker: Error response from daemon: Conflict. The container name is already in use"

This error usually occurs when the user tries to start a container with repeated container name of the new container.

Solution:

Before starting a new container, please confirm whether the container name already exists. If present, use a different name.

If you want to delete an existing container, you can use the following command:

docker stop <container_name>
docker rm <container_name></container_name></container_name>

Question 5: When starting Docker, the error "docker: Error response from daemon: OCI runtime create failed: container_linux.go" :345…”

This error usually occurs when using a newer version of Docker, because its default runtime environment is OCI (Open Container Initiative).

Solution:

In order to solve this problem, please upgrade the Linux kernel to version 4.11 or above and install the latest version of the libcgroup package.

If you cannot upgrade the kernel or libcgroup package, you can add an --exec-driver option to the Docker startup command to set the container's runtime environment to an older version of lxc.

For example, the following command will start an Ubuntu container in the lxc environment:

docker run --name mycontainer --exec-driver=lxc -it ubuntu /bin/bash

Summary

The above are some of the things you may encounter during the installation and use of Docker on CentOS systems. some problems and solutions. I hope this article can help readers avoid these problems and successfully use Docker to solve their software deployment needs.

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