Discover how to install Docker on CentOS offline with our detailed guide. Follow step-by-step instructions to set up Docker without an internet connection, ensuring a smooth and successful installation. #centlinux #linux #docker
Table of Contents
What is Docker?
Docker is a computer software, that performs operating-system-level virtualization, also known as Containerization. Docker is developed by Docker Inc. Docker uses predefined and custom images to create and run containers. These images are provided through Docker Hub (an online Docker registry).
Containers are isolated from each other having their own set of binaries, libraries and configuration files. Unlike virtual machines, containers may or may not have their own operating systems. The containers are run by the host operating system Kernel, therefore, a container is much light weight as compare to a Hypervisor based virtual machine.
Docker is an important part of today’s DevOps environments, where it is mostly used for application virtualization..
Docker is a freemium software. Because a Community Edition (CE) with limited features is available as free while an Enterprise Edition (EE) is available with more features and a license cost.
Docker is also provided with Red Hat Atomic Host 7, which is a RHEL 7 based operating system optimized for hosting containers. You can read our previous guide about installation of Red Hat Atomic Host 7.
Read Also: How to install Docker on Rocky Linux 9
Environment Specification
In this article, we are using two isolated CentOS 7 based Linux servers. One server has access to Internet, while the other server isn’t connected with Internet.
| Offline Server | Online Server | |
| Hostname: | docker-offline.example.com | docker-online.example.com |
| Operating System: | CentOS 7.6 | CentOS 7.6 |
| Internet: | No | Yes |
Linux operating systems on both machines must be same, otherwise the software package versions may not matched and it won’t work.
Recommended Online Training: Docker and Kubernetes – The Complete Developers Guide
Install EPEL Yum Repository on CentOS 7
By using a ssh client, connect with docker-online.example.com as root user.
To install Docker on CentOS offline, we requires some software packages that are available in EPEL (Extra Packages for Enterprise Linux) yum repository. Therefore, we have to install EPEL yum repository first.
# yum install -y epel-release.noarch
EPEL yum repository has been installed.
Install Docker Yum Repository on CentOS 7
Install Docker CE yum repository on our CentOS 7 operating system.
# yum-config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo Loaded plugins: fastestmirror adding repo from: https://download.docker.com/linux/centos/docker-ce.repo grabbing file https://download.docker.com/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo repo saved to /etc/yum.repos.d/docker-ce.repo
Enable Docker CE (Nightly) yum repository.
# yum-config-manager --enable docker-ce-nightly
We have added two yum repositories in our Linux server. Therefore, we should build cache for yum package manager.
# yum makecache fast Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile epel/x86_64/metalink | 9.1 kB 00:00 * base: repo.inara.pk * epel: sg.fedora.ipserverone.com * extras: repo.inara.pk * updates: repo.inara.pk base | 3.6 kB 00:00 docker-ce-nightly | 3.5 kB 00:00 docker-ce-stable | 3.5 kB 00:00 extras | 3.4 kB 00:00 updates | 3.4 kB 00:00 Metadata Cache Created
Download Docker CE and Software Dependencies
Create a directory to download Docker CE and dependent software packages.
# mkdir ~/docker # cd ~/docker
Download Docker CE and dependent packages following Linux command.
# yumdownloader --resolve docker-ce
Docker CE and dependent software packages has been downloaded.
# ls audit-libs-python-2.8.4-4.el7.x86_64.rpm checkpolicy-2.5-8.el7.x86_64.rpm containerd.io-1.2.2-3.el7.x86_64.rpm container-selinux-2.74-1.el7.noarch.rpm docker-ce-18.09.1-3.el7.x86_64.rpm docker-ce-cli-18.09.1-3.el7.x86_64.rpm libcgroup-0.41-20.el7.x86_64.rpm libseccomp-2.3.1-3.el7.x86_64.rpm libsemanage-python-2.5-14.el7.x86_64.rpm policycoreutils-2.5-29.el7_6.1.x86_64.rpm policycoreutils-python-2.5-29.el7_6.1.x86_64.rpm python-IPy-0.75-6.el7.noarch.rpm setools-libs-3.3.8-4.el7.x86_64.rpm
The above packages versions may be different on your Linux server due to the Kernel version that your are using.
Now, we need to transfer these files to docker-offline.example.com. Therefore, we are creating a tarball of all downloaded software packages.
# tar czf ~/docker.tar.gz *
Now, we have a tarball of Docker CE and dependent software packages.
# ls ~ -lh total 58M -rw-------. 1 root root 1.5K Dec 22 11:29 anaconda-ks.cfg drwxr-xr-x. 2 root root 4.0K Feb 8 21:32 docker -rw-r--r--. 1 root root 58M Feb 8 21:39 docker.tar.gz
Install Docker on CentOS Offline
Transfer the docker.tar.gz tarball to docker-offline.example.com and copy at home directory of root user.
# ls -lh total 58M -rw-------. 1 root root 1.5K Dec 22 12:23 anaconda-ks.cfg -rw-r--r--. 1 root root 58M Feb 8 21:39 docker.tar.gz
Extract the docker.tar.gz tarball.
# mkdir docker # tar xf docker.tar.gz -C ~/docker
You can now install Docker on CentOS offline by installing all packages from the ~/docker directory.
# cd docker # rpm -ivh --replacefiles --replacepkgs *.rpm warning: containerd.io-1.2.2-3.el7.x86_64.rpm: Header V4 RSA/SHA512 Signature, key ID 621e9f35: NOKEY Preparing... ################################# [100%] Updating / installing... 1:policycoreutils-2.5-29.el7_6.1 ################################# [ 8%] 2:libcgroup-0.41-20.el7 ################################# [ 15%] 3:setools-libs-3.3.8-4.el7 ################################# [ 23%] 4:python-IPy-0.75-6.el7 ################################# [ 31%] 5:libsemanage-python-2.5-14.el7 ################################# [ 38%] 6:libseccomp-2.3.1-3.el7 ################################# [ 46%] 7:docker-ce-cli-1:18.09.1-3.el7 ################################# [ 54%] 8:containerd.io-1.2.2-3.el7 ################################# [ 62%] 9:checkpolicy-2.5-8.el7 ################################# [ 69%] 10:audit-libs-python-2.8.4-4.el7 ################################# [ 77%] 11:policycoreutils-python-2.5-29.el7################################# [ 85%] 12:container-selinux-2:2.74-1.el7 ################################# [ 92%] 13:docker-ce-3:18.09.1-3.el7 ################################# [100%]
Start and enable Docker service.
# systemctl enable docker.service Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service. # systemctl start docker.service
We have successfully installed Docker CE on an offline Linux server.
Download Docker images from Docker Hub
To create containers, we required Docker images, that are available via Docker Hub or a Private Docker Registry server.
Since, our Linux server is not connected to Internet, therefore, we cannot pull Docker images directly from Docker Hub.
The workaround of this problem is to download Docker images on an online system and then transfer and load these images to our offline CentOS 7 server.
Note: You must have Docker CE installed on the online system first. Because we will use the docker command to download and save images from Docker Hub.
# docker pull jenkins/jenkins Using default tag: latest latest: Pulling from jenkins/jenkins 8700b2d54fbc: Pull complete 4613d2e35dec: Pull complete 08320da45709: Pull complete 8f947c5bbe77: Pull complete 51cf55002ec2: Pull complete 9537066ae19a: Pull complete e156275467ac: Pull complete Digest: sha256:20981c20164347728fca4774b3c45f5d24a73d857e8b9b8e6faf4100cfc0812d Status: Downloaded newer image for jenkins/jenkins:latest
Similarly, pull more images according to your requirement.
Save Jenkins image in a tar file.
# docker save jenkins/jenkins > ~/jenkins.tar # ls -lh total 690M -rw-------. 1 root root 1.5K Dec 22 11:29 anaconda-ks.cfg -rw-r--r--. 1 root root 690M Feb 12 22:07 jenkins.tar
Transfer jenkins.tar to docker-offline.example.com.
Load jenkins.tar image by using docker command.
# docker load < jenkins.tar 13d5529fd232: Loading layer 105.6MB/105.6MB abc3250a6c7f: Loading layer 24.07MB/24.07MB 5924ca705d38: Loading layer 9.216kB/9.216kB 852edd42bb1e: Loading layer 4.608kB/4.608kB 03b3a4ed2e5a: Loading layer 3.072kB/3.072kB 37dfb8384dfe: Loading layer 7.168kB/7.168kB 8f65ce1dc902: Loading layer 12.29kB/12.29kB Loaded image: jenkins/jenkins:latest
Jenkins image has been loaded into Docker. You can use following Linux command to verify this.
# docker images REPOSITORY TAG IMAGE ID CREATED SIZE jenkins/jenkins latest 9b74eda1c268 32 hours ago 704MB
Now, we can create and run Docker containers from the Jenkins/Jenkins image.
To start using Docker you should refer to Docker Documentation or buy and read Docker Deep Dive (PAID LINK).
Final Thoughts
Installing Docker on CentOS offline can be a bit challenging, but with the right steps, it becomes manageable. This guide aims to make the process straightforward and successful. If you need further assistance or prefer to have an expert handle the installation, I’m here to help.
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