Main resource I used to learn Docker is Udemy Docker Mastery. At the end of this series I want to write up a quick getting started with docker because there’s a lot of content it seems to go through to start using docker.


This post covers docker installation, running/starting a container, viewing the (stdout/error) logs, and inspecting the container.

Installing Docker on Desktop (Ubuntu)

Ubuntu Docker setup

curl -fsSL | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt update
sudo apt install docker-ce docker-ce-cli docker-compose-plugin

# verify that it works
sudo service docker start
sudo docker run hello-world

Then Install Docker Desktop on Ubuntu

# Download deb file from the above link.

sudo apt update
mv docker-desktop-<version>-<arch>.deb /tmp/
sudo apt install /tmp/docker-desktop-<version>-<arch>.deb

If it still doesn’t start it might be because it requires KVM. Install KVM on Ubuntu

Make sure (SVM) or KVM is enabled in the BIOS. Otherwise you’ll see the message Docker is stopped in Docker Desktop.

Optional Installing on a Linux Server

I prefer to use Docker’s automated script to add their repository and install all dependencies: curl -sSL sh but you can also install in a more manual method by following specific instructions that Docker provides for your Linux distribution.

Installing Docker Credentials

Install Docker credentials

sudo apt install pass

tar -xf docker-credential-pass-v0.6.4-amd64.tar.gz
chmod +x docker-credential-pass
sudo mv docker-credential-pass /usr/local/bin/

sudo apt install gnupg2
gpg2 --gen-key


docker login

Running Docker

Make sure to start up the docker daemon or the docker desktop.

docker version
docker info

docker --help

Let’s run a container.

#old way is to just remove the container subcommand.
docker container run --publish 80:80 nginx

docker container run --publish 80:80 --detach nginx # this will run it in the background.

# If container doesn't automatically stop 
docker stop <containerid/name>

docker container run --publish 80:80 --detach --name webhost nginx  # note that putting arguments after the container name sends the commands as arguments to the container causing errors.

What did docker (container) run do?

  • Downloaded the image nginx from Docker Hub.
  • Started a new container from that iamge.
  • Opened post 80 on the host IP
  • Routes that traffic to the container IP, port 80.
  • Note the first arg is the host port so it can be 8080 and the second arg is the container port.

View all of the containers

docker container ls # docker ps
docker container ls -a

View the logs

docker container logs webhost

# OR docker logs webhost

docker container top webhost

Remove the old containers

docker container rm a01

docker container rm -f webhost ast a01 we3

What are containers?

They’re just a process. They have limits on resources they can access and exit when process stops.

It’s a restricted process.

HW 1 Manage multiple containers

Start a nginx on port 80:80, mysql port 8080:80, and httpd server on port 3306:3306

for mysql pass –env or -e with MYSQL_RANDOM_ROOT_PASSWORD=true

View the logs to view the container password. docker container logs <container>

docker container run --detach -p 80:80 --name nginx nginx
docker container run --detach --env MYSQL_RANDOM_ROOT_PASSWORD=true -p 3306:3306 --name mysql mysql
docker container run --detach -p 8080:80 --name httpd httpd

docker container logs mysql
# docker logs mysql1 2>&1 | grep GENERATED

docker container stop nginx httpd mysql
docker container rm nginx httpd mysql

Some tools to inspect containers

docker info, inspect, stats

Getting inside a container to mess with its internals

docker container run -it
docker container exec -it

To reattach to a stopped container use start and -a

docker container run -it --name ubuntu ubuntu  # the default command is bash so it'll drop you into bash
apt install curl
# type exit to leave
docker container start -ai ubuntu

Use exec to attach to an already running container.

docker container exec -it mysql bash  # alternatively use mariadb

Get to know Alpine

docker container run -it alpine sh
apk # the apt or pacman equivalent for alpine