Installation of Docker in Ubuntu: remove old docker, docker.io, containerd packages; add Docker’s official apt repo; install docker-ce. The DigitalOcean guide walks through the same steps for older Ubuntu; the 2026 version for 22.04 and 24.04 follows. The team that skips the ‘remove old versions’ step has conflicts.
Table of contents
- Remove old versions
- Install prerequisites
- Add Docker’s GPG key and repo
- Install Docker
- Verify
- Post-install: non-root user
- Ubuntu-specific notes
- Troubleshooting
- FAQ
Remove old versions
sudo apt remove docker docker-engine docker.io containerd runcOr if dpkg -l | grep -i docker shows nothing, skip. The team that has old docker-engine packages gets conflicts without this step.
Install prerequisites
sudo apt update
sudo apt install ca-certificates curl gnupgThe team that has these installed is ready to add Docker’s repo.
Add Docker’s GPG key and repo
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] 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 updateThe team that runs on Ubuntu 24.04 sees noble in the repo URL. On 22.04 it’s jammy.
Install Docker
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-pluginInstalls the latest stable. The team that wants a specific version uses apt list -a docker-ce to see available versions, then sudo apt install docker-ce=<version>.
Verify
sudo systemctl status docker
sudo docker run hello-worldThe team that sees ‘active (running)’ and the hello-world output has a working install.
Post-install: non-root user
sudo usermod -aG docker $USER
newgrp docker
docker run hello-world # no sudoThe team that adds the user to docker group has rootless docker usage (still root inside containers).
Ubuntu-specific notes
- Ubuntu’s
docker.iopackage is older - use Docker’s repo. - Ubuntu’s AppArmor might block docker;
sudo aa-complain /usr/bin/dockerif needed. - Ubuntu’s default firewall (ufw) doesn’t block docker by default.
- Ubuntu 24.04 uses cgroup v2 by default; some older docker features need adjustment.
Troubleshooting
Cannot connect to Docker daemon:
sudo systemctl start docker.- Check
/var/run/docker.sockexists. - Check user is in docker group.
Permission denied:
sudo usermod -aG docker $USERthen log out/in.- Or
sudo docker(avoid).
FAQ
Which Ubuntu version is supported?
Docker officially supports the current LTS (22.04, 24.04) and recent non-LTS. Older versions may work with the docker.io package but won’t get updates.
Can I install Docker without root?
Yes - rootless mode. More complex setup but better security. The team that has compliance requirements uses rootless.
What’s the difference between docker-ce and docker-ee?
docker-ce: Community Edition, free. docker-ee: Enterprise Edition, paid with support. Most teams use docker-ce.
Do I need to uninstall the snap version of Docker?
Yes if installed. Snap’s docker runs in a confined environment with limitations. The team that uses the apt version has full features.
How do I update Docker?
sudo apt update && sudo apt upgrade upgrades Docker along with other packages. The team that uses unattended-upgrades has automatic Docker updates.
If you are sizing the infrastructure for the kind of project this post covers, the RunxBuild hosting calculator is the right place to model the line items. The compute, the memory, the storage, the bandwidth, the database - each one is a separate number, and the team’s mental model for the platform is the sum of those numbers. The RunxBuild dashboard is where the team sees the actual usage in one place.
Useful related references: