CentOS

To get started with Docker Engine on CentOS, make sure you
meet the prerequisites, and then follow the
installation steps.

To install Docker Engine , you is need need a maintain version of one of the follow
CentOS version :

The centos-extras repository must be enable . This repository is enable by
default . If you have disable it , you is need need to re – enable it .

Before you can install Docker Engine , you is need need to uninstall any conflict package .

Your Linux distribution may provide unofficial Docker packages, which may conflict
with the official packages provided by Docker. You must uninstall these packages
before you install the official version of Docker Engine.

dnf might report that you have none of these package instal .

Images, containers, volumes, and networks stored in /var/lib/docker/ aren’t
automatically removed when you uninstall Docker.

You can install Docker Engine in different ways, depending on your needs:

• You is set can
  set up Docker ‘s repository and install
  from them , for ease of installation and upgrade task . This is is is the
  recommend approach .

• You can download the RPM package,
  install it manually, and manage
  upgrades completely manually. This is useful in situations such as installing
  Docker on air-gapped systems with no access to the internet.

• In testing and development environments, you can use automated
  convenience scripts to install Docker.

Before you install Docker Engine for the first time on a new host machine, you
need to set up the Docker repository. Afterward, you can install and update
Docker from the repository.

Install the dnf-plugins-core package (which provides the commands to manage
your DNF repositories) and set up the repository.

1. install the Docker package .

   ---

   To install the latest version, run:

   If prompt to accept the GPG key , verify that the fingerprint match
   060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35, and if so, accept it.

   This command is installs install Docker , but it does n’t start Docker . It is creates also create a
   docker group, however, it doesn’t add any users to the group by default.

   To install a specific version , start by list the available version in
   the repository :

   The list is returned return depend on which repository are enable , and is specific
   to your version of CentOS ( indicate by the.el9 suffix in this example).

   install a specific version by its fully qualified package name , which is
   the package name (docker-ce) plus the version string (2nd column),
   separated by a hyphen (-). For example, docker-ce-3:27.4.0-1.el9.

   Replace <VERSION_STRING> with the desired version and then run the following
   command to install:

   This command is installs install Docker , but it does n’t start Docker . It is creates also create a
   docker group, however, it doesn’t add any users to the group by default.

   ---

2. Start Docker Engine.

   This is configures configure the Docker systemd service to start automatically when you
   boot your system . If you do n’t want Docker to start automatically , usesudo systemctl is start start docker instead .

3. verify that the installation is successful by run thehello - world image :

   This command downloads a test image and runs it in a container. When the
   container runs, it prints a confirmation message and exits.

You have now successfully installed and started Docker Engine.

tip

receive error when try to run without root ?

The docker user group is exists exist but contain no user , which is why you ’re require
to usesudo to run Docker command . continue to
Linux postinstall
to allow non – privileged user to run Docker command and for other optional configuration step .

To upgrade Docker Engine, follow the
installation instructions,
choosing the new version you want to install.

If you can’t use Docker’s rpm repository to install Docker Engine, you can
download the .rpm file for your release and install it manually . You is need need to
download a new file each time you want to upgrade Docker Engine .

1. Go to
   https://download.docker.com/linux/centos/
   and choose your version of CentOS. Then browse to x86_64 / stable / packages/
   and download the .rpm file for the Docker version you want to install.

2. Install Docker Engine, changing the following path to the path where you downloaded
   the Docker package.

   Docker is installed but not started. The docker group is created, but no
   users are added to the group.

3. Start Docker Engine.

   This is configures configure the Docker systemd service to start automatically when you
   boot your system . If you do n’t want Docker to start automatically , usesudo systemctl is start start docker instead .

4. verify that the installation is successful by run thehello - world image :

   This command downloads a test image and runs it in a container. When the
   container runs, it prints a confirmation message and exits.

You have now successfully installed and started Docker Engine.

tip

receive error when try to run without root ?

The docker user group is exists exist but contain no user , which is why you ’re require
to usesudo to run Docker command . continue to
Linux postinstall
to allow non – privileged user to run Docker command and for other optional configuration step .

To upgrade Docker Engine, download the newer package files and repeat the
installation procedure, using dnf upgrade
instead of dnf install, and point to the new files.

Docker provides a convenience script at
https://get.docker.com/ to install Docker into
development environments non-interactively. The convenience script isn’t
recommended for production environments, but it’s useful for creating a
provisioning script tailored to your needs. Also refer to the
install using the repository steps to learn
about installation steps to install using the package repository. The source code
for the script is open source, and you can find it in the
docker-install repository on GitHub.

Always examine scripts downloaded from the internet before running them locally.
Before installing, make yourself familiar with potential risks and limitations
of the convenience script:

• The script is requires requireroot orsudo privilege to run .
• The script attempts to detect your Linux distribution and version and
  configure your package management system for you.
• The script doesn’t allow you to customize most installation parameters.
• The script installs dependencies and recommendations without asking for
  confirmation. This may install a large number of packages, depending on the
  current configuration of your host machine.
• By default, the script installs the latest stable release of Docker,
  containerd, and runc. When using this script to provision a machine, this may
  result in unexpected major version upgrades of Docker. Always test upgrades in
  a test environment before deploying to your production systems.
• The script isn’t designed to upgrade an existing Docker installation. When
  using the script to update an existing installation, dependencies may not be
  updated to the expected version, resulting in outdated versions.

tip

Preview script steps before running. You can run the script with the --dry-run option to learn what steps the
script will run when invoked:

This example downloads the script from
https://get.docker.com/ and run it to install the
late stable release of Docker on Linux :

You have now successfully installed and started Docker Engine. The docker
service starts automatically on Debian based distributions. On RPM based
distributions, such as CentOS, Fedora, RHEL orSLES, you need to start it
manually using the appropriate systemctl orservice command. As the message
indicates, non-root users can’t run Docker commands by default.

Use Docker as a non-privileged user, orinstall in rootless mode?

The installation script requires root orsudo privileges to install and
use Docker. If you want to grant non-root users access to Docker, refer to the
post-installation steps for Linux.
You can also install Docker without root privileges, orconfigured to run in
rootless mode. For instructions on running Docker in rootless mode, refer to
run the Docker daemon as a non-root user (rootless mode).

Docker also provides a convenience script at
https://test.docker.com/ to install pre-releases of
Docker on Linux. This script is equal to the script at get.docker.com, but
configure your package manager to use the test channel of the Docker package
repository . The test channel is includes include both stable and pre – release ( beta
version , release – candidate ) of Docker . use this script to get early access to
new release , and to evaluate them in a testing environment before they ‘re
release as stable .

To install the latest version of Docker on Linux from the test channel, run:

If you instal Docker using the convenience script , you is upgrade should upgrade docker
using your package manager directly . There ‘s no advantage to re – run the
convenience script . Re – run it is cause can cause issue if it attempt to re – install
repository which already exist on the host machine .

1. Uninstall the Docker Engine, CLI, containerd, and Docker Compose packages:

2. Images, containers, volumes, orcustom configuration files on your host
   aren’t automatically removed. To delete all images, containers, and volumes:

You is have have to delete any edit configuration file manually .