Apr 28, 2021
Instructions for installing Docker Engine on Ubuntu. Got multiple Docker repositories? If you have multiple Docker repositories enabled, installing or updating without specifying a version in the apt-get install or apt-get update command always installs the highest possible version, which may not be appropriate for your stability needs. Install Docker on Linux No matter your distribution of choice, you’ll need a 64-bit installation and a kernel at 3.10 or newer. Kernels older than 3.10 do not have the necessary features Docker requires to run containers; data loss and kernel panics occur frequently under certain conditions. Oct 22, 2018 sudo apt-get remove docker docker-engine docker.io Step 3: Install Docker on Ubuntu 18.04. To install Docker on Ubuntu, in the terminal window enter the command: sudo apt install docker.io Step 4: Start and Automate Docker. The Docker service needs to be setup to run at startup. To do so, type in each command followed by enter: sudo systemctl.
Docker is an open-source technology that is used to deploy applications through containers. It is a relatively new platform but is constantly updated and features a wide community of users.
Docker is a great tool that solves the age-old dilemma between developers and system administrators – while developers say that an app works on their machines, system admins worry about changing its libraries and requirements. With Docker, that is no longer a problem as it allows a more transparent method of communication.
It is essentially a virtual machine, that lets you run images. With Docker, you don’t need to worry about the requirements and that’s a perfect fit for many VPS projects.
Docker is highly popular among developers and can be installed without any problems in our favorite Linux distribution.
So with this in mind, let’s learn how to install Docker on Ubuntu 18.04.
Why do Users Install Docker on Ubuntu
Let’s do a quick rundown of the main benefits users experience when using Docker.
Docker is adaptable allowing users to carry out continuous testing, deploy and check outcomes as many times as they want, with as many implications. It becomes a laboratory in itself where a user can experiment with new commands to fill in the container and make it functional in various tasks.
This utility also supports multi-cloud computing, which means it is adaptable to applications that use cloud computing for saving data on servers. Think of services like Microsoft Azure, Puppet, Ansible, OpenStack and others.
Segregation in an isolated environment is another core aspect of Docker that attracts developers. In addition, docker works with OS sensitive mount points like /sys and /proc which are read-only mounts.
How to Install Docker on Ubuntu 18.04
Docker is not in the official Ubuntu 18.04 repositories. However, the installation process will not be complicated because of it. Let’s begin.
1. Access Your VPS
First, we have to connect to the server using SSH. If you’re having trouble, check out our PuTTY tutorial.
2. Update Your System
Then, the system needs to be updated to make it safer and reliable to install Docker. Run the following two commands:
3. Install Prerequisite Packages
Once we have updated the system, we need to install some necessary packages before we are ready to install Docker. You can do this with the help of a single command:
To better understand the command above here is a short description of what it means:
- apt-transport-https – lets the package manager transfer files and data over https
- ca-certificates – lets the web browser and system check security certificates
- curl – transfers data
- software-properties-common – adds scripts to manage the software
4. Add the Docker Repositories
Now we have to add the Docker repositories. This will make the installation process much easier. This enables us to use the officially supported method of the installation.
First, we add the GPG key, by entering the following command in the command line:
Next, we add the repository:
After that, just update the repository information:
Make sure you are installing from the Docker repo instead of the default Ubuntu repo with this command:
A correct output will look like the following with different version numbers:
As you can see, docker-ce is not installed, so we can move on to the next step.
5. Install Docker on Ubuntu 18.04
We are almost done. Use the apt command to install Docker:
6. Check Docker Status
Once the installation is complete, it is a good idea to check the status of the service:
That’s it, you now know how to install Docker on Ubuntu 18.04. Easy, right? Let’s learn some Docker basics!
How to Start Using Docker on Ubuntu 18.04
Once Docker is installed, all we need to do is use the test image to check that everything is working as it should. Do this with the following command:
Now, if we want to search for available images we just have to use the following command:
Just replace your query with the bracketed text.
For example, if we want to search for an image related to Debian, the command and output will look like this:
Then, to download the image to our computer, we will use the name of the image along with the following command:
For example, the command might look like this:
Normally, users will have several images in their system. We can list them with the command:
The list will look much like the one you receive when you enter a search query.
After that, we can execute our image using the pull command and the Image ID.
There are options that extend the functionality of the command itself. For example, the -i option makes the image execution interactive. Or the -d option that executes it in the background.
Once we are running an image, we can end its execution by using the key combination CTRL+D.
Finally, if we want to use Docker without root privileges, we need to run the following command:
After that, restart the system, and the changes will be applied.
Using the Docker Command
The Docker command consists of passing options, commands, and arguments. The syntax will follow the following form:
To view all of the available subcommands use the following command:
To view the options available with a command:
Here are Docker 18′ available subcommands:
Its main novelty is that it allows you to “package” an application or a set of services in containers. A Docker container is an instance of an application that contains all the libraries and components necessary for an application to work. From a practical point of view, a container is like a reduced virtual machine that functions independently from the operating system where a specific application or service is executed.
A Docker container is generated from an image that is the result of the packaged app or service. It can contain a complete operating system or pre-installed applications. That is to say, the container will start to work from an image.
There are many Docker images that we can use in our daily work cycle. We can also create our own images and further expand the possibilities of this great application.
Docker’s advantages make software deployment much more efficient and convenient than before. Thanks to this, developers will have no problems in knowing how your application will run outside the test environment. On the other hand, the system administrator will not have to struggle with system changes or looking for necessary libraries.
In this tutorial, we showed you the first steps to take with Docker. To unlock the true potential of this great utility, we recommend to check out the official documentation. Happy developing!
Edward is an expert communicator with years of experience in IT as a writer, marketer, and Linux enthusiast. IT is a core pillar of his life, personal and professional. Edward's goal is to encourage millions to achieve an impactful online presence. He also really loves dogs, guitars, and everything related to space.
Run a Docker Container in Ubuntu. In order to create and run a Docker container, first you need to run a command into a downloaded CentOS image, so a basic command would be to check the distribution version file inside the container using cat command, as shown. $ docker run centos cat /etc/issue 14. When running docker desktop version 188.8.131.52 (40323) on: OS Name: Microsoft Windows 10 Pro OS Version: 10.0.19013 N/A Build 19013 Eben though WSL 2 based engine is enabled in Settings/General docker container run hello-world on Ubuntu rep.
Estimated reading time: 15 minutes
Run Ubuntu In Docker On Windows 10
Welcome to Docker Desktop! The Docker Desktop for Windows user manual provides information on how to configure and manage your Docker Desktop settings.
For information about Docker Desktop download, system requirements, and installation instructions, see Install Docker Desktop.
The Docker Desktop menu allows you to configure your Docker settings such as installation, updates, version channels, Docker Hub login,and more.
This section explains the configuration options accessible from the Settings dialog.
Open the Docker Desktop menu by clicking the Docker icon in the Notifications area (or System tray):
Select Settings to open the Settings dialog:
On the General tab of the Settings dialog, you can configure when to start and update Docker.
Start Docker when you log in - Automatically start Docker Desktop upon Windows system login.
Expose daemon on tcp://localhost:2375 without TLS - Click this option to enable legacy clients to connect to the Docker daemon. You must use this option with caution as exposing the daemon without TLS can result in remote code execution attacks.
Send usage statistics - By default, Docker Desktop sends diagnostics,crash reports, and usage data. This information helps Docker improve andtroubleshoot the application. Clear the check box to opt out. Docker may periodically prompt you for more information.
The Resources tab allows you to configure CPU, memory, disk, proxies, network, and other resources. Different settings are available for configuration depending on whether you are using Linux containers in WSL 2 mode, Linux containers in Hyper-V mode, or Windows containers.
The Advanced tab is only available in Hyper-V mode, because in WSL 2 mode and Windows container mode these resources are managed by Windows. In WSL 2 mode, you can configure limits on the memory, CPU, and swap size allocatedto the WSL 2 utility VM.
Use the Advanced tab to limit resources available to Docker.
CPUs: By default, Docker Desktop is set to use half the number of processorsavailable on the host machine. To increase processing power, set this to ahigher number; to decrease, lower the number.
Memory: By default, Docker Desktop is set to use
2 GB runtime memory,allocated from the total available memory on your machine. To increase the RAM, set this to a higher number. To decrease it, lower the number.
Swap: Configure swap file size as needed. The default is 1 GB.
Disk image size: Specify the size of the disk image.
Disk image location: Specify the location of the Linux volume where containers and images are stored.
You can also move the disk image to a different location. If you attempt to move a disk image to a location that already has one, you get a prompt asking if you want to use the existing image or replace it.
The File sharing tab is only available in Hyper-V mode, because in WSL 2 mode and Windows container mode all files are automatically shared by Windows.
Use File sharing to allow local directories on Windows to be shared with Linux containers.This is especially useful forediting source code in an IDE on the host while running and testing the code in a container.Note that configuring file sharing is not necessary for Windows containers, only Linux containers. If a directory is not shared with a Linux container you may get
file not found or
cannot start service errors at runtime. See Volume mounting requires shared folders for Linux containers.
File share settings are:
Add a Directory: Click
+and navigate to the directory you want to add.
Apply & Restart makes the directory available to containers using Docker’sbind mount (
Tips on shared folders, permissions, and volume mounts
Share only the directories that you need with the container. File sharing introduces overhead as any changes to the files on the host need to be notified to the Linux VM. Sharing too many files can lead to high CPU load and slow filesystem performance.
Shared folders are designed to allow application code to be edited on the host while being executed in containers. For non-code items such as cache directories or databases, the performance will be much better if they are stored in the Linux VM, using a data volume (named volume) or data container.
Docker Desktop sets permissions to read/write/execute for users, groups and others 0777 or a+rwx.This is not configurable. See Permissions errors on data directories for shared volumes.
Windows presents a case-insensitive view of the filesystem to applications while Linux is case-sensitive. On Linux it is possible to create 2 separate files:
Test, while on Windows these filenames would actually refer to the same underlying file. This can lead to problems where an app works correctly on a developer Windows machine (where the file contents are shared) but fails when run in Linux in production (where the file contents are distinct). To avoid this, Docker Desktop insists that all shared files are accessed as their original case. Therefore if a file is created called
test, it must be opened as
test. Attempts to open
Testwill fail with “No such file or directory”. Similarly once a file called
testis created, attempts to create a second file called
Shared folders on demand
You can share a folder “on demand” the first time a particular folder is used by a container.
If you run a Docker command from a shell with a volume mount (as shown in theexample below) or kick off a Compose file that includes volume mounts, you get apopup asking if you want to share the specified folder.
You can select to Share it, in which case it is added your Docker Desktop Shared Folders list and available tocontainers. Alternatively, you can opt not to share it by selecting Cancel.
Docker Desktop lets you configure HTTP/HTTPS Proxy Settings andautomatically propagates these to Docker. For example, if you set your proxysettings to
http://proxy.example.com, Docker uses this proxy when pulling containers.
Your proxy settings, however, will not be propagated into the containers you start.If you wish to set the proxy settings for your containers, you need to defineenvironment variables for them, just like you would do on Linux, for example:
For more information on setting environment variables for running containers,see Set environment variables.
The Network tab is not available in Windows container mode because networking is managed by Windows.
You can configure Docker Desktop networking to work on a virtual private network (VPN). Specify a network address translation (NAT) prefix and subnet mask to enable Internet connectivity.
DNS Server: You can configure the DNS server to use dynamic or static IP addressing.
Install Docker Ubuntu 18.04 Command Line
Some users reported problems connecting to Docker Hub on Docker Desktop. This would manifest as an error when trying to run
docker commands that pull images from Docker Hub that are not alreadydownloaded, such as a first time run of
docker run hello-world. If youencounter this, reset the DNS server to use the Google DNS fixed address:
184.108.40.206. For more information, seeNetworking issues in Troubleshooting.
Updating these settings requires a reconfiguration and reboot of the Linux VM.
In WSL 2 mode, you can configure which WSL 2 distributions will have the Docker WSL integration.
By default, the integration will be enabled on your default WSL distribution. To change your default WSL distro, run
wsl --set-default <distro name>. (For example, to set Ubuntu as your default WSL distro, run
wsl --set-default ubuntu).
You can also select any additional distributions you would like to enable the WSL 2 integration on.
For more details on configuring Docker Desktop to use WSL 2, see Docker Desktop WSL 2 backend.
The Docker Engine page allows you to configure the Docker daemon to determine how your containers run.
Type a JSON configuration file in the box to configure the daemon settings. For a full list of options, see the Docker Enginedockerd commandline reference.
Click Apply & Restart to save your settings and restart Docker Desktop.
Install Docker Command Line Ubuntu 18 04
On the Command Line page, you can specify whether or not to enable experimental features.
You can toggle the experimental features on and off in Docker Desktop. If you toggle the experimental features off, Docker Desktop uses the current generally available release of Docker Engine.
Experimental features provide early access to future product functionality.These features are intended for testing and feedback only as they may changebetween releases without warning or can be removed entirely from a futurerelease. Experimental features must not be used in production environments.Docker does not offer support for experimental features.
For a list of current experimental features in the Docker CLI, see Docker CLI Experimental features.
docker version to verify whether you have enabled experimental features. Experimental modeis listed under
Server data. If
true, then Docker isrunning in experimental mode, as shown here:
The Kubernetes tab is not available in Windows container mode.
Docker Desktop includes a standalone Kubernetes server that runs on your Windows machince, sothat you can test deploying your Docker workloads on Kubernetes. To enable Kubernetes support and install a standalone instance of Kubernetes running as a Docker container, select Enable Kubernetes.
For more information about using the Kubernetes integration with Docker Desktop, see Deploy on Kubernetes.
The Restart Docker Desktop and Reset to factory defaults options are now available on the Troubleshoot menu. For information, see Logs and Troubleshooting.
Visit our Logs and Troubleshooting guide for more details.
Log on to our Docker Desktop for Windows forum to get help from the community, review current user topics, or join a discussion.
Log on to Docker Desktop for Windows issues on GitHub to report bugs or problems and review community reported issues.
Run Ubuntu In Docker On Windows
For information about providing feedback on the documentation or update it yourself, see Contribute to documentation.
Switch between Windows and Linux containers
From the Docker Desktop menu, you can toggle which daemon (Linux or Windows)the Docker CLI talks to. Select Switch to Windows containers to use Windowscontainers, or select Switch to Linux containers to use Linux containers(the default).
For more information on Windows containers, refer to the following documentation:
Microsoft documentation on Windows containers.
Build and Run Your First Windows Server Container (Blog Post)gives a quick tour of how to build and run native Docker Windows containers on Windows 10 and Windows Server 2016 evaluation releases.
Getting Started with Windows Containers (Lab)shows you how to use the MusicStoreapplication with Windows containers. The MusicStore is a standard .NET application and,forked here to use containers, is a good example of a multi-container application.
To understand how to connect to Windows containers from the local host, seeLimitations of Windows containers for
localhostand published ports
Settings dialog changes with Windows containers
When you switch to Windows containers, the Settings dialog only shows those tabs that are active and apply to your Windows containers:
If you set proxies or daemon configuration in Windows containers mode, theseapply only on Windows containers. If you switch back to Linux containers,proxies and daemon configurations return to what you had set for Linuxcontainers. Your Windows container settings are retained and become availableagain when you switch back.
The Docker Desktop Dashboard enables you to interact with containers and applications and manage the lifecycle of your applications directly from your machine. The Dashboard UI shows all running, stopped, and started containers with their state. It provides an intuitive interface to perform common actions to inspect and manage containers and Docker Compose applications. For more information, see Docker Desktop Dashboard.
Select Sign in /Create Docker ID from the Docker Desktop menu to access your Docker Hub account. Once logged in, you can access your Docker Hub repositories directly from the Docker Desktop menu.
For more information, refer to the following Docker Hub topics:
Docker Desktop enables you to sign into Docker Hub using two-factor authentication. Two-factor authentication provides an extra layer of security when accessing your Docker Hub account.
You must enable two-factor authentication in Docker Hub before signing into your Docker Hub account through Docker Desktop. For instructions, see Enable two-factor authentication for Docker Hub.
After you have enabled two-factor authentication:
Line Command Prompt
Go to the Docker Desktop menu and then select Sign in / Create Docker ID.
Enter your Docker ID and password and click Sign in.
After you have successfully signed in, Docker Desktop prompts you to enter the authentication code. Enter the six-digit code from your phone and then click Verify.
After you have successfully authenticated, you can access your organizations and repositories directly from the Docker Desktop menu.
Adding TLS certificates
You can add trusted Certificate Authorities (CAs) to your Docker daemon to verify registry server certificates, and client certificates, to authenticate to registries.
How do I add custom CA certificates?
Can We Run Ubuntu Docker On Windows
Docker Desktop supports all trusted Certificate Authorities (CAs) (root orintermediate). Docker recognizes certs stored under Trust RootCertification Authorities or Intermediate Certification Authorities.
Docker Desktop creates a certificate bundle of all user-trusted CAs based onthe Windows certificate store, and appends it to Moby trusted certificates. Therefore, if an enterprise SSL certificate is trusted by the user on the host, it is trusted by Docker Desktop.
Run Ubuntu In Docker On Windows 7
To learn more about how to install a CA root certificate for the registry, seeVerify repository client with certificatesin the Docker Engine topics.
How do I add client certificates?
You can add your client certificatesin
~/.docker/certs.d/<MyRegistry>:<Port>/client.key. You do not need to push your certificates with
When the Docker Desktop application starts, it copies the
~/.docker/certs.d folder on your Windows system to the
/etc/docker/certs.ddirectory on Moby (the Docker Desktop virtual machine running on Hyper-V).
You need to restart Docker Desktop after making any changes to the keychainor to the
~/.docker/certs.d directory in order for the changes to take effect.
The registry cannot be listed as an insecure registry (seeDocker Daemon). Docker Desktop ignorescertificates listed under insecure registries, and does not send clientcertificates. Commands like
docker run that attempt to pull from the registryproduce error messages on the command line, as well as on the registry.
To learn more about how to set the client TLS certificate for verification, seeVerify repository client with certificatesin the Docker Engine topics.
Where to go next
Run Ubuntu In Docker On Windows 10
Try out the walkthrough at Get Started.
Dig in deeper with Docker Labs example walkthroughs and source code.
Refer to the Docker CLI Reference Guide.