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moby--moby/docs/installation/linux/centos.md
Sebastiaan van Stijn b2bb4e11aa
Cleanup / sync RHEL, CentOS, Fedora installation docs
These installation procedures are very similar, so
synchronized these docs and removed some differences.

Also;

- updated markdown, added language-hints where possible
- replaced "service docker start" with "systemctl start"
- replaced "chkconfig docker on" with "systemctl enable"
- added "systemctl enable" to the list of steps for
  installation, because most people want to have docker
  started automatically (and overlooked this step).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2016-09-19 21:30:57 +02:00

238 lines
6.7 KiB
Markdown

<!--[metadata]>
+++
aliases = [ "/engine/installation/centos/"]
title = "Installation on CentOS"
description = "Instructions for installing Docker on CentOS"
keywords = ["Docker, Docker documentation, requirements, linux, centos, epel, docker.io, docker-io"]
[menu.main]
parent = "engine_linux"
weight=-4
+++
<![end-metadata]-->
# CentOS
Docker runs on CentOS 7.X. An installation on other binary compatible EL7
distributions such as Scientific Linux might succeed, but Docker does not test
or support Docker on these distributions.
These instructions install Docker using release packages and installation
mechanisms managed by Docker, to be sure that you get the latest version
of Docker. If you wish to install using CentOS-managed packages, consult
your CentOS release documentation.
## Prerequisites
Docker requires a 64-bit OS and version 3.10 or higher of the Linux kernel.
To check your current kernel version, open a terminal and use `uname -r` to
display your kernel version:
```bash
$ uname -r
3.10.0-229.el7.x86_64
```
Finally, it is recommended that you fully update your system. Keep in mind
that your system should be fully patched to fix any potential kernel bugs.
Any reported kernel bugs may have already been fixed on the latest kernel
packages.
## Install Docker Engine
There are two ways to install Docker Engine. You can [install using the `yum`
package manager](#install-with-yum). Or you can use `curl` with the [`get.docker.com`
site](#install-with-the-script). This second method runs an installation script
which also installs via the `yum` package manager.
### Install with yum
1. Log into your machine as a user with `sudo` or `root` privileges.
2. Make sure your existing packages are up-to-date.
```bash
$ sudo yum update
```
3. Add the `yum` repo.
```bash
$ sudo tee /etc/yum.repos.d/docker.repo <<-'EOF'
[dockerrepo]
name=Docker Repository
baseurl=https://yum.dockerproject.org/repo/main/centos/7/
enabled=1
gpgcheck=1
gpgkey=https://yum.dockerproject.org/gpg
EOF
```
4. Install the Docker package.
```bash
$ sudo yum install docker-engine
```
5. Enable the service.
```bash
$ sudo systemctl enable docker.service
```
6. Start the Docker daemon.
```bash
$ sudo systemctl start docker
```
7. Verify `docker` is installed correctly by running a test image in a container.
$ sudo docker run --rm hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
c04b14da8d14: Pull complete
Digest: sha256:0256e8a36e2070f7bf2d0b0763dbabdd67798512411de4cdcf9431a1feb60fd9
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker Hub account:
https://hub.docker.com
For more examples and ideas, visit:
https://docs.docker.com/engine/userguide/
If you need to add an HTTP Proxy, set a different directory or partition for the
Docker runtime files, or make other customizations, read our Systemd article to
learn how to [customize your Systemd Docker daemon options](../../admin/systemd.md).
### Install with the script
1. Log into your machine as a user with `sudo` or `root` privileges.
2. Make sure your existing packages are up-to-date.
```bash
$ sudo yum update
```
3. Run the Docker installation script.
```bash
$ curl -fsSL https://get.docker.com/ | sh
```
This script adds the `docker.repo` repository and installs Docker.
4. Enable the service.
```bash
$ sudo systemctl enable docker.service
```
5. Start the Docker daemon.
```bash
$ sudo systemctl start docker
```
6. Verify `docker` is installed correctly by running a test image in a container.
```bash
$ sudo docker run hello-world
```
If you need to add an HTTP Proxy, set a different directory or partition for the
Docker runtime files, or make other customizations, read our Systemd article to
learn how to [customize your Systemd Docker daemon options](../../admin/systemd.md).
## Create a docker group
The `docker` daemon binds to a Unix socket instead of a TCP port. By default
that Unix socket is owned by the user `root` and other users can access it with
`sudo`. For this reason, `docker` daemon always runs as the `root` user.
To avoid having to use `sudo` when you use the `docker` command, create a Unix
group called `docker` and add users to it. When the `docker` daemon starts, it
makes the ownership of the Unix socket read/writable by the `docker` group.
>**Warning**: The `docker` group is equivalent to the `root` user; For details
>on how this impacts security in your system, see [*Docker Daemon Attack
>Surface*](../../security/security.md#docker-daemon-attack-surface) for details.
To create the `docker` group and add your user:
1. Log into your machine as a user with `sudo` or `root` privileges.
2. Create the `docker` group.
```bash
$ sudo groupadd docker
```
3. Add your user to `docker` group.
```bash
$ sudo usermod -aG docker your_username`
```
4. Log out and log back in.
This ensures your user is running with the correct permissions.
5. Verify that your user is in the docker group by running `docker` without `sudo`.
```bash
$ docker run hello-world
```
## Start the docker daemon at boot
Configure the Docker daemon to start automatically when the host starts:
```bash
$ sudo systemctl enable docker
```
## Uninstall
You can uninstall the Docker software with `yum`.
1. List the installed Docker packages.
```bash
$ yum list installed | grep docker
docker-engine.x86_64 1.7.1-0.1.el7@/docker-engine-1.7.1-0.1.el7.x86_64
```
2. Remove the package.
```bash
$ sudo yum -y remove docker-engine.x86_64
```
This command does not remove images, containers, volumes, or user-created
configuration files on your host.
3. To delete all images, containers, and volumes, run the following command:
```bash
$ rm -rf /var/lib/docker
```
4. Locate and delete any user-created configuration files.