How to Install Docker on Ubuntu 22.04

In this manual, I will explain, step by step, how to install Docker on Ubuntu 22.04.

You can install Docker using the apt repository or install it from a package.

The second option might be necessary for Ubuntu servers that have strict security policies and are not connected to the apt repository or are limited to some specific resources.

In this manual, I will use the installation from the apt repository method.

1 Set up the Docker apt repository.

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl gnupg
sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

# Add the repository to Apt sources:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

2 Install the Docker packages.

To install the latest version, run:

 sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Lets run hello-world image to verify the installation:

sudo docker run hello-world

If you see Hello from Docker! message, it’s a sign that you have now successfully installed and started Docker Engine.

As you noticed, you have to run docker with sudo and you will get permissions denied if you will try to run docker run without sudo.

That because 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 only access it using sudo. The docker daemon always runs as the root user.

If you don’t want 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.

• Add the docker group (it might be already exist):

sudo groupadd docker

• Add the connected user “$USER” to the docker group:

sudo gpasswd -a $USER docker

This adds the current user to the docker group. If you want to add another user, change the username to match it.

• Either do a newgrp docker or log out/in to activate the changes to groups:

newgrp docker

• Run docker run hello-world command to test it:

docker run hello-world

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