Docker & Kubernetes
Docker
NOTICE: The following documentation refers to installation of Docker on a Red Hat Enterprise or CentOS Linux Server
Overlay Linux Kernel Driver
To begin with, Docker runs best with the "overlay2" Linux kernel driver enabled/loaded. Run this command as the root/superuser or with sudo, as seen here to enable the kernel module at each reboot:
[jamie@cos8vm51.dawgland.com:~]$ sudo echo "overlay" > /etc/modules-load.d/overlay.conf;
Reboot and double check that the Linux kernel overlay module is loaded with this command:
[jamie@cos8vm51.dawgland.com:~]$ lsmod | grep overlay overlay 135168 0 [jamie@cos8vm51.dawgland.com:~]$
If you get the "overlay 135168 0" response after typing the "lsmod | grep overlay" command, you are good to go The actual number doesn't matter, as long as it shows the word "overlay", indicating the "Overlay" Linux kernel module is loaded into the kernel. If not, you need a newer Linux kernel that supports the overlay2 driver, which is beyond the scope of this article, and you basically need to pick a different newer Linux distribution.
Required Packages
Docker requires some basic utilities and tools provided by specific Linux packages. For Red Hat Enterprise Linux and CentOS Linux, these packages at minimum are required:
- device-mapper-persistent-data
- dnf-utils
- fuse-overlayfs
- lvm2
- wget
To install these packages, or at least double check to make sure they are installed, and if not, then install them, open up a terminal if you are not already at the command prompt of the machine you want to install Docker on. Then, become the root/superuser. I use the "sudo" utility to do this, but you may have other methods depending on your system and preferences.
Here is an example of me doing so on a brand new VM(Virtual Machine) with a minimal installation of CentOS 8, fully updated using the "DNF" utility, which I will also demonstrate the command used to check for updates and refresh the package cache.
First, become the root user:
[jamie@cos8minvm.dawgland.com:~]$ sudo su - Last login: Tue Apr 6 19:41:31 PDT 2021 on pts/0 [root@cos8minvm.dawgland.com:~]#
And now that I am the "root", aka the "SuperUser", I will check for updates and refresh the package cache in one command:
[root@cos8minvm.dawgland.com:~]# dnf check-update --refresh CentOS Linux 8 - AppStream 7.5 kB/s | 4.3 kB 00:00 CentOS Linux 8 - BaseOS 12 kB/s | 3.9 kB 00:00 CentOS Linux 8 - Extras 51 B/s | 1.5 kB 00:30 Extra Packages for Enterprise Linux Modular 8 - 27 kB/s | 15 kB 00:00 Extra Packages for Enterprise Linux 8 - x86_64 33 kB/s | 14 kB 00:00 [root@cos8minvm.dawgland.com:~]#
And the actual command to install the required packages, using the DNF utility. If you are running a pre-8.x version of Red Hat Enterprise or CentOS, substitute "yum" in place of "dnf":
[root@cos8minvm.dawgland.com:~]# dnf -y install device-mapper-persistent-data dnf-utils fuse-overlayfs lvm2 wget
Last metadata expiration check: 0:05:46 ago on Tue 06 Apr 2021 08:06:14 PM PDT.
Dependencies resolved.
================================================================================
Package Arch Version Repo Size
================================================================================
Installing:
device-mapper-persistent-data x86_64 0.8.5-4.el8 baseos 468 k
fuse-overlayfs x86_64 1.3.0-2.module_el8.3.0+699+d61d9c41
appstream 72 k
lvm2 x86_64 8:2.03.09-5.el8 baseos 1.6 M
wget x86_64 1.19.5-10.el8 appstream 734 k
yum-utils noarch 4.0.17-5.el8 baseos 68 k
Installing dependencies:
device-mapper-event x86_64 8:1.02.171-5.el8 baseos 268 k
device-mapper-event-libs x86_64 8:1.02.171-5.el8 baseos 267 k
fuse3 x86_64 3.2.1-12.el8 baseos 50 k
fuse3-libs x86_64 3.2.1-12.el8 baseos 94 k
libaio x86_64 0.3.112-1.el8 baseos 33 k
lvm2-libs x86_64 8:2.03.09-5.el8 baseos 1.1 M
Enabling module streams:
container-tools rhel8
Transaction Summary
================================================================================
Install 11 Packages
Total download size: 4.7 M
Installed size: 11 M
Downloading Packages:
(1/11): device-mapper-event-1.02.171-5.el8.x86_ 644 kB/s | 268 kB 00:00
(2/11): device-mapper-event-libs-1.02.171-5.el8 2.3 MB/s | 267 kB 00:00
(3/11): fuse-overlayfs-1.3.0-2.module_el8.3.0+6 130 kB/s | 72 kB 00:00
(4/11): device-mapper-persistent-data-0.8.5-4.e 3.9 MB/s | 468 kB 00:00
(5/11): fuse3-libs-3.2.1-12.el8.x86_64.rpm 1.6 MB/s | 94 kB 00:00
(6/11): libaio-0.3.112-1.el8.x86_64.rpm 564 kB/s | 33 kB 00:00
(7/11): fuse3-3.2.1-12.el8.x86_64.rpm 231 kB/s | 50 kB 00:00
(8/11): lvm2-2.03.09-5.el8.x86_64.rpm 6.2 MB/s | 1.6 MB 00:00
(9/11): yum-utils-4.0.17-5.el8.noarch.rpm 1.2 MB/s | 68 kB 00:00
(10/11): lvm2-libs-2.03.09-5.el8.x86_64.rpm 2.7 MB/s | 1.1 MB 00:00
(11/11): wget-1.19.5-10.el8.x86_64.rpm 485 kB/s | 734 kB 00:01
--------------------------------------------------------------------------------
Total 1.0 MB/s | 4.7 MB 00:04
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : libaio-0.3.112-1.el8.x86_64 1/11
Installing : device-mapper-event-libs-8:1.02.171-5.el8.x86_64 2/11
Installing : device-mapper-event-8:1.02.171-5.el8.x86_64 3/11
Running scriptlet: device-mapper-event-8:1.02.171-5.el8.x86_64 3/11
Installing : lvm2-libs-8:2.03.09-5.el8.x86_64 4/11
Installing : device-mapper-persistent-data-0.8.5-4.el8.x86_64 5/11
Installing : fuse3-libs-3.2.1-12.el8.x86_64 6/11
Running scriptlet: fuse3-libs-3.2.1-12.el8.x86_64 6/11
Installing : fuse3-3.2.1-12.el8.x86_64 7/11
Installing : fuse-overlayfs-1.3.0-2.module_el8.3.0+699+d61d9c41 8/11
Running scriptlet: fuse-overlayfs-1.3.0-2.module_el8.3.0+699+d61d9c41 8/11
Installing : lvm2-8:2.03.09-5.el8.x86_64 9/11
Running scriptlet: lvm2-8:2.03.09-5.el8.x86_64 9/11
Installing : yum-utils-4.0.17-5.el8.noarch 10/11
Installing : wget-1.19.5-10.el8.x86_64 11/11
Running scriptlet: wget-1.19.5-10.el8.x86_64 11/11
Verifying : fuse-overlayfs-1.3.0-2.module_el8.3.0+699+d61d9c41 1/11
Verifying : wget-1.19.5-10.el8.x86_64 2/11
Verifying : device-mapper-event-8:1.02.171-5.el8.x86_64 3/11
Verifying : device-mapper-event-libs-8:1.02.171-5.el8.x86_64 4/11
Verifying : device-mapper-persistent-data-0.8.5-4.el8.x86_64 5/11
Verifying : fuse3-3.2.1-12.el8.x86_64 6/11
Verifying : fuse3-libs-3.2.1-12.el8.x86_64 7/11
Verifying : libaio-0.3.112-1.el8.x86_64 8/11
Verifying : lvm2-8:2.03.09-5.el8.x86_64 9/11
Verifying : lvm2-libs-8:2.03.09-5.el8.x86_64 10/11
Verifying : yum-utils-4.0.17-5.el8.noarch 11/11
Installed:
device-mapper-event-8:1.02.171-5.el8.x86_64
device-mapper-event-libs-8:1.02.171-5.el8.x86_64
device-mapper-persistent-data-0.8.5-4.el8.x86_64
fuse-overlayfs-1.3.0-2.module_el8.3.0+699+d61d9c41.x86_64
fuse3-3.2.1-12.el8.x86_64
fuse3-libs-3.2.1-12.el8.x86_64
libaio-0.3.112-1.el8.x86_64
lvm2-8:2.03.09-5.el8.x86_64
lvm2-libs-8:2.03.09-5.el8.x86_64
wget-1.19.5-10.el8.x86_64
yum-utils-4.0.17-5.el8.noarch
Complete!
[root@cos8minvm.dawgland.com:~]#
Add Docker-CE Software Repository to System
Use this command to add the Docker-CE software repository to your /etc/yum.repos.d directory. The CE in "Docker-CE" stands for "Community Edition", in case you're wondering! Having the Docker-CE yum repository allows you to easily add and remove Docker related software. Here's the command to install the "repo", as it's abbreviated:
[root@cos8minvm.dawgland.com:~]# yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo Adding repo from: https://download.docker.com/linux/centos/docker-ce.repo [root@cos8minvm.dawgland.com:~]#
Kubernetes
Kubernetes info coming soon...