Docker Ubuntu Setup Guide

Introduction

Docker has revolutionized how we develop, package, and deploy applications by enabling consistent environments across different systems. This guide will walk you through setting up an Ubuntu-based Docker environment, from installation to advanced usage patterns. Whether you’re new to Docker or looking to optimize your containerized Ubuntu workflow, this guide has you covered.

Installing Docker

Before you can start working with Ubuntu containers, you need to install Docker on your system.

Installing Docker on Ubuntu Host

# Update your package index
sudo apt update

# Install prerequisites
sudo apt install -y apt-transport-https ca-certificates curl software-properties-common

# Add Docker's official GPG key
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

# Set up the stable repository
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

# Update the package index again
sudo apt update

# Install Docker Engine
sudo apt install -y docker-ce docker-ce-cli containerd.io

# Add your user to the docker group to run Docker without sudo
sudo usermod -aG docker $USER

# Apply the new group membership
newgrp docker

Installing Docker on macOS

Download and install Docker Desktop from the official website
Open Docker Desktop and follow the setup wizard

Basic Ubuntu Container Usage

Once Docker is installed, you can start working with Ubuntu containers.

Pulling an Ubuntu Image

# Pull the latest Ubuntu image
docker pull ubuntu:latest

# Pull a specific version (e.g., Ubuntu 22.04 LTS)
docker pull ubuntu:22.04

Running an Ubuntu Container

Interactive Mode

# Run a container interactively with a bash shell
docker run -it ubuntu:latest bash

This command:

-i: Keeps STDIN open
-t: Allocates a pseudo-TTY
bash: Runs the bash shell inside the container

Accessing a Running Container

# Access a running container with bash
docker exec -it my-ubuntu bash

Stopping and Removing Containers

# Stop a running container
docker stop my-ubuntu

# Remove a container
docker rm my-ubuntu

# Force remove a running container
docker rm -f my-ubuntu

Creating Custom Ubuntu Images

Creating custom Ubuntu images allows you to package your applications and dependencies for easier deployment.

Basic Dockerfile Example

# Use Ubuntu 22.04 as the base image
FROM ubuntu:22.04

# Set non-interactive mode for apt
ENV DEBIAN_FRONTEND=noninteractive

# Update and install packages
RUN apt-get update && apt-get install -y \
    python3 \
    python3-pip \
    nginx \
    vim \
    curl \
    && apt-get clean \
    && rm -rf /var/lib/apt/lists/*

# Set the working directory
WORKDIR /app

# Copy application files
COPY . /app/

# Expose a port
EXPOSE 80

# Define the command to run when the container starts
CMD ["nginx", "-g", "daemon off;"]

Building the Image

# Build an image from the Dockerfile in the current directory
docker build -t my-ubuntu-app .

# Build with a specific tag
docker build -t my-ubuntu-app:1.0 .

Running the Custom Image

# Run the custom image
docker run -d -p 8080:80 --name my-webapp my-ubuntu-app

This command:

-p 8080:80: Maps port 8080 on the host to port 80 in the container
--name my-webapp: Names the container

Persistent Data with Volumes

Docker containers are ephemeral, meaning any data inside them is lost when they’re removed. Volumes solve this problem.

Creating and Using Volumes

# Create a named volume
docker volume create my-data

# Run a container with the volume mounted
docker run -it -v my-data:/data ubuntu:latest bash

Inside the container, any data written to /data will persist in the my-data volume.

Bind Mounts

You can also mount host directories into containers:

# Mount a host directory to a container directory
docker run -it -v $(pwd)/host-data:/container-data ubuntu:latest bash

Docker Compose for Multi-Container Applications

Docker Compose simplifies managing multi-container applications.

Example Docker Compose File

# docker-compose.yml
version: '3'

services:
  web:
    build: ./web
    ports:
      - "8080:80"
    volumes:
      - web-data:/var/www/html
    depends_on:
      - db
    networks:
      - app-network

  db:
    image: mysql:8.0
    volumes:
      - db-data:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: rootpassword
      MYSQL_DATABASE: mydb
      MYSQL_USER: user
      MYSQL_PASSWORD: password
    networks:
      - app-network

networks:
  app-network:

volumes:
  web-data:
  db-data:

Using Docker Compose

# Start all services defined in docker-compose.yml
docker-compose up

# Run in detached mode
docker-compose up -d

# Stop all services
docker-compose down

# Stop services and remove volumes
docker-compose down -v

One-Line Setup Commands

For quick setup, here are one-line commands combining multiple steps:

Basic Ubuntu Container Setup

docker pull ubuntu:22.04 && docker run -d --name my-ubuntu -v my-data:/data ubuntu:22.04 tail -f /dev/null && docker exec -it my-ubuntu bash

Web Server Setup

echo "<html><body><h1>Hello from Docker!</h1></body></html>" > index.html && docker run -d --name nginx-ubuntu -p 8080:80 -v $(pwd)/index.html:/var/www/html/index.html ubuntu:22.04 bash -c "apt-get update && apt-get install -y nginx && nginx -g 'daemon off;'"