12/28/2021

Linux Docker Group

82

Estimated reading time: 11 minutes

To get started with Docker Engine on CentOS, make sure youmeet the prerequisites, theninstall Docker.

Prerequisites

This requires the user to be privileged enough to run docker, i.e. Being in the docker group or being root. Any other Docker Linux image should work, e.g., debian. It can be used to break out from restricted environments by spawning an interactive system shell. The resulting is a root shell. Docker run -v /:/mnt -rm -it alpine chroot. This video shows how privilege escalation can happen when a user is part of the docker group on a Linux system. Users in the docker group will typically have.

Add user to the docker group. The docker installation should have created a dockerroot group. The first step is to declare you user as member of that group. Usermod -aG dockerroot. That is not all, the user will still not be able to connect to the daemon as the corresponding socket ( /var/run/docker.sock) belongs to root. # docker run -it -rm archlinux bash -c 'echo hello world' If you want to be able to run the docker CLI command as a non-root user, add your user to the docker user group, re-login, and restart docker.service. 2.5.6.3 Deploying MySQL on Windows and Other Non-Linux Platforms with Docker The Docker deployment framework supports easy installation and configuration of MySQL Server. This section explains how to use a MySQL Server Docker image.

OS requirements

To install Docker Engine, you need a maintained version of CentOS 7 or 8.Archived versions aren’t supported or tested.

The centos-extras repository must be enabled. This repository is enabled bydefault, but if you have disabled it, you need tore-enable it.

The overlay2 storage driver is recommended.

Uninstall old versions

Older versions of Docker were called docker or docker-engine. If these areinstalled, uninstall them, along with associated dependencies.

It’s OK if yum reports that none of these packages are installed.

The contents of /var/lib/docker/, including images, containers, volumes, andnetworks, are preserved. The Docker Engine package is now called docker-ce.

Installation methods

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

  • Most usersset up Docker’s repositories and installfrom them, for ease of installation and upgrade tasks. This is therecommended approach.

  • Some users download the RPM package andinstall it manually and manageupgrades completely manually. This is useful in situations such as installingDocker on air-gapped systems with no access to the internet.

  • In testing and development environments, some users choose to use automatedconvenience scripts to install Docker.

Install using the repository

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

Set up the repository

Install the yum-utils package (which provides the yum-config-managerutility) and set up the stable repository.

Optional: Enable the nightly or test repositories.

These repositories are included in the docker.repo file above but are disabledby default. You can enable them alongside the stable repository. The followingcommand enables the nightly repository.

To enable the test channel, run the following command:

You can disable the nightly or test repository by running theyum-config-manager command with the --disable flag. To re-enable it, usethe --enable flag. The following command disables the nightly repository.

Learn about nightly and test channels.

Install Docker Engine

Linux Docker Group
  1. Install the latest version of Docker Engine and containerd, or go to the next step to install a specific version:

    If prompted to accept the GPG key, verify that the fingerprint matches060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35, and if so, accept it.

    Got multiple Docker repositories?

    If you have multiple Docker repositories enabled, installingor updating without specifying a version in the yum install oryum update command always installs the highest possible version,which may not be appropriate for your stability needs.

    This command installs Docker, but it doesn’t start Docker. It also creates adocker group, however, it doesn’t add any users to the group by default.

  2. To install a specific version of Docker Engine, list the available versionsin the repo, then select and install:

    a. List and sort the versions available in your repo. This example sorts results by version number, highest to lowest, and is truncated:

    The list returned depends on which repositories are enabled, and is specificto your version of CentOS (indicated by the .el7 suffix in this example).

    b. Install a specific version by its fully qualified package name, which is the package name (docker-ce) plus the version string (2nd column) starting at the first colon (:), up to the first hyphen, separated by a hyphen (-). For example, docker-ce-18.09.1.

    This command installs Docker, but it doesn’t start Docker. It also creates adocker group, however, it doesn’t add any users to the group by default.

  3. Start Docker.

  4. Verify that Docker Engine is installed correctly by running the hello-worldimage.

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

This installs and runs Docker Engine. Use sudo to run Dockercommands. Continue to Linux postinstall to allownon-privileged users to run Docker commands and for other optional configurationsteps.

Upgrade Docker Engine

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

Install from a package

If you cannot use Docker’s repository to install Docker, you can download the.rpm file for your release and install it manually. You need to downloada 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.

    Note

    To install a nightly or test (pre-release) package,change the word stable in the above URL to nightly or test.Learn about nightly and test channels.

  2. Install Docker Engine, changing the path below to the path where you downloadedthe Docker package.

    Docker is installed but not started. The docker group is created, but nousers are added to the group.

  3. Start Docker.

  4. Verify that Docker Engine is installed correctly by running the hello-worldimage.

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

This installs and runs Docker Engine. Use sudo to run Docker commands.Continue to Post-installation steps for Linux to allownon-privileged users to run Docker commands and for other optional configurationsteps.

Upgrade Docker Engine

To upgrade Docker Engine, download the newer package file and repeat theinstallation procedure, using yum -y upgradeinstead of yum -y install, and point to the new file.

Install using the convenience script

Docker provides a convenience script at get.docker.comto install Docker into development environments quickly and non-interactively.The convenience script is not recommended for production environments, but can beused as an example to create a provisioning script that is tailored to your needs.Also refer to the install using the repositorysteps to learn about installation steps to install using the package repository.The source code for the script is open source, and can be found in thedocker-install repository on GitHub.

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

  • The script requires root or sudo privileges to run.
  • The script attempts to detect your Linux distribution and version andconfigure your package management system for you, and does not allow you tocustomize most installation parameters.
  • The script installs dependencies and recommendations without asking forconfirmation. This may install a large number of packages, depending on thecurrent 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 inunexpected major version upgrades of Docker. Always test (major) upgrades ina test environment before deploying to your production systems.
  • The script is not designed to upgrade an existing Docker installation. Whenusing the script to update an existing installation, dependencies may not beupdated to the expected version, causing outdated versions to be used.

Tip: preview script steps before running

You can run the script with the DRY_RUN=1 option to learn what steps thescript will execute during installation:

This example downloads the script from get.docker.comand runs it to install the latest stable release of Docker on Linux:

Docker is installed. The docker service starts automatically on Debian baseddistributions. On RPM based distributions, such as CentOS, Fedora, RHEL or SLES,you need to start it manually using the appropriate systemctl or service command.As the message indicates, non-root users cannot run Docker commands by default.

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

The installation script requires root or sudo privileges to install anduse Docker. If you want to grant non-root users access to Docker, refer to thepost-installation steps for Linux.Docker can also be installed without root privileges, or configured to runin rootless mode. For instructions on running Docker in rootless mode, refer torun the Docker daemon as a non-root user (rootless mode).

Install pre-releases

Docker also provides a convenience script at test.docker.comto install pre-releases of Docker on Linux. This script is equivalent to thescript at get.docker.com, but configures your package manager to enable the“test” channel from our package repository, which includes both stable andpre-releases (beta versions, release-candidates) of Docker. Use this script toget early access to new releases, and to evaluate them in a testing environmentbefore they are released as stable.

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

Upgrade Docker after using the convenience script

If you installed Docker using the convenience script, you should upgrade Dockerusing your package manager directly. There is no advantage to re-running theconvenience script, and it can cause issues if it attempts to re-addrepositories which have already been added to the host machine.

Uninstall Docker Engine

  1. Uninstall the Docker Engine, CLI, and Containerd packages:

  2. Images, containers, volumes, or customized configuration files on your hostare not automatically removed. To delete all images, containers, andvolumes:

Linux Docker Group 2

You must delete any edited configuration files manually.

Next steps

  • Continue to Post-installation steps for Linux.
  • Review the topics in Develop with Docker to learn how to build new applications using Docker.

Add Yourself To Docker Group

requirements, apt, installation, centos, rpm, install, uninstall, upgrade, update
  • Most Viewed News

    • Install Mysql Macos
    • Create A Macos Usb Installer
    • Duet Display Download Mac