Docker container virtualization

Posted by webaddict on Tue, 01 Feb 2022 02:43:30 +0100

1. Centos deploys Docker container virtualization platform

Installing Docker environment dependencies

yum install -y yum-utils device-mapper-persistent-data lvm2

Configure yum source of domestic Docker (Alibaba cloud)##

yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

Docker installation

yum install docker-ce docker-ce-cli containerd.io -y

Docker CE cli is a docker command line tool. containerd.io is a container interface related package.

Start the Docker service and start it

systemctl start docker && systemctl enable docker

2. Pull image - configure image acceleration address

First, you can use the * * docker search imageName command to find the required image. Then use docker pull imageName * * to pull the image. If the version number is not added, pull latest.

However, this method is slow to pull images. Several methods are recommended below.

(1) Change the image download address

It is recommended to use Alibaba cloud Docker image accelerator to improve the pull speed. You can also choose other accelerators, such as Netease, with the same principle.

Netease image addresses are also provided here: https://c.163.com/hub#/m/home/

Log in to Alibaba cloud image accelerator console, https://cr.console.aliyun.com . The image tool - image accelerator in the menu bar on the left side of the console page will display the assigned acceleration address in the format of https://xxxxxxxx.mirror.aliyuncs.com .

Edit the daemon.xml using vim JSON file (this file does not exist by default, and VIM will create it automatically).

vim /etc/docker/daemon.json

daemon.json file content is added as follows. Multiple image acceleration addresses can be configured ["address 1", "address 2", "address 3]:

{
  "registry-mirrors": ["https://xxxxxxxx.mirror.aliyuncs.com"]
}

Then execute the following two commands in sequence:

systemctl daemon-reload
systemctl restart docker

Finally, use the docker info command to check whether the address of Registry Mirrors is an acceleration address. Then pull the image, which will be very fast.

(2) Pull the image offline

This method uses the operations related to Docker image import and export.

First of all, you need to download the image file (suffix. tar) through other channels in advance, upload it to the Linux server through ftp, and then import the image with the following command.

docker load -i xxx.tar

Similarly, you can also use the following command to export an image in the images repository. Of which, XXX Tar is the name of the exported tar file. imageName:latest selects the image of the specified TAG

docker load -o xxx.tar imageName:latest

3. Enable Docker routing forwarding function

It is on by default. This configuration is not required.

However, if the console reports the following error when you start the Docker instance, you need to configure it.

WARNING: IPv4 forwarding is disabled. Networking will not work.

First use VIM / etc / sysctl Conf command, add content net ipv4. ip_ forward = 1.

# sysctl settings are defined through files in
# /usr/lib/sysctl.d/, /run/sysctl.d/, and /etc/sysctl.d/.
#
# Vendors settings live in /usr/lib/sysctl.d/.
# To override a whole file, create a new file with the same in
# /etc/sysctl.d/ and put new settings there. To override
# only specific settings, add a file with a lexically later
# name in /etc/sysctl.d/ and put new settings there.
#
# For more information, see sysctl.conf(5) and sysctl.d(5).
net.ipv4.ip_forward = 1

Then use sysctl -p to make the configuration effective. You can also use cat /proc/sys/net/ipv4/ip_forward to check whether the routing forwarding function is enabled. The following is the console history.

[root@atlantis ~]# vim /etc/sysctl.conf
[root@atlantis ~]# sysctl -p
net.ipv4.ip_forward = 1
[root@atlantis ~]# cat /proc/sys/net/ipv4/ip_forward
1
[root@atlantis ~]#

Then close the firewall, restart the Docker service, and use iptables -L -n to find many more Docker related firewall rules.

[root@atlantis ~]# systemctl stop firewalld && systemctl disable firewalld
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@atlantis ~]# systemctl restart docker
[root@atlantis ~]# iptables -L -n
······

4. Basic use of docker

There are too many commands. Please use Baidu for specific methods.

Docker command tab automatic completion

If some Docker commands cannot be completed automatically by using tab, execute the following three commands in sequence.

yum install -y bash-completion
source /usr/share/bash-completion/completions/docker
source /usr/share/bash-completion/bash_completion

Topics: Linux Docker

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