docker

Docker

Containerize applications for faster deployment and scaling

🚀 About

In this HashiQube DevOps lab, you'll get hands-on experience with Docker. You'll learn how to:

• Build a custom Docker image from a Dockerfile
• Run Docker containers
• Configure a Docker daemon with authentication
• Set up a Docker registry

This lab follows the official Docker installation guide for Ubuntu-based systems.

📋 Provision

Github Codespace

bash docker/docker.sh

Vagrant

vagrant up --provision-with basetools,docsify,docker

Docker Compose

docker compose exec hashiqube /bin/bash
bash hashiqube/basetools.sh
bash docker/docker.sh
bash docsify/docsify.sh

📦 What You'll Build

When you run the provisioner, it will:

1. Install Docker on your HashiQube environment
2. Build an Apache 2.4 container from a Dockerfile
3. Run the container and expose it to your host machine
4. Make the container accessible at http://localhost:8889

🛠️ Dockerfile Walkthrough

Below is the Dockerfile used to build the Apache web server container:

FROM ubuntu:18.04

# Install dependencies
RUN apt-get update && \
 apt-get -y install apache2

# Install apache and write hello world message
RUN echo 'Hello World!' > /var/www/html/index.html

# Configure apache
RUN echo '. /etc/apache2/envvars' > /root/run_apache.sh && \
 echo 'mkdir -p /var/run/apache2' >> /root/run_apache.sh && \
 echo 'mkdir -p /var/lock/apache2' >> /root/run_apache.sh && \
 echo '/usr/sbin/apache2 -D FOREGROUND' >> /root/run_apache.sh && \
 chmod 755 /root/run_apache.sh

EXPOSE 80

CMD /root/run_apache.sh

This Dockerfile:

• Uses Ubuntu 18.04 as the base image
• Installs Apache web server
• Creates a simple "Hello World" web page
• Sets up a script to run Apache in the foreground
• Exposes port 80 for web traffic
• Specifies the command to run when the container starts

📊 Monitoring Docker

HashiQube includes Prometheus and Grafana for monitoring Docker containers.

For detailed information, see the Monitoring Docker guide.

🧩 Key Docker Concepts

Images vs Containers

• Images: Read-only templates used to create containers
• Containers: Runnable instances of images

Basic Docker Commands

# List running containers
docker ps

# List all containers (including stopped ones)
docker ps -a

# List available images
docker images

# Pull an image from Docker Hub
docker pull ubuntu:latest

# Run a container
docker run -d -p 8080:80 --name my-container nginx

# Stop a container
docker stop my-container

# Remove a container
docker rm my-container

# Remove an image
docker rmi nginx

🔌 Docker Networking

Docker creates isolated networks for containers by default. You can:

• Create custom networks
• Connect containers to multiple networks
• Configure network settings

# Create a custom network
docker network create my-network

# Run a container connected to the custom network
docker run -d --network=my-network --name my-db postgres

# Connect an existing container to a network
docker network connect my-network my-container

📦 Docker Volumes

Volumes provide persistent storage for containers:

# Create a named volume
docker volume create my-data

# Run a container with a volume
docker run -d -v my-data:/data --name my-container ubuntu

# Mount a host directory as a volume
docker run -d -v /host/path:/container/path --name my-container ubuntu

🔍 Docker Provisioner

The script below automates the setup of Docker in your HashiQube environment:

#!/bin/bash

# Print the commands that are run
set -x

# Stop execution if something fails
set -e

# This script provisions Docker
# https://docs.docker.com/install/linux/docker-ce/ubuntu/

# Check if Docker exists
if ! [ -x "$(command -v docker)" ]; then
  echo 'Docker is not installed, installing it ...' >&2
  
  # Install prerequisites
  sudo apt-get install -y \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg-agent \
    software-properties-common

  # Add Docker's official GPG key
  curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

  # Add Docker repository
  sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

  # Update packages and install Docker
  sudo apt-get update
  sudo apt-get install -y docker-ce docker-ce-cli containerd.io
  
  # Add current user to Docker group
  sudo usermod -aG docker vagrant

  # Create our Dockerfile
  cat << 'EOF' > /tmp/Dockerfile
FROM ubuntu:18.04
# Install dependencies
RUN apt-get update && \
 apt-get -y install apache2
# Install apache and write hello world message
RUN echo 'Hello World!' > /var/www/html/index.html
# Configure apache
RUN echo '. /etc/apache2/envvars' > /root/run_apache.sh && \
 echo 'mkdir -p /var/run/apache2' >> /root/run_apache.sh && \
 echo 'mkdir -p /var/lock/apache2' >> /root/run_apache.sh && \
 echo '/usr/sbin/apache2 -D FOREGROUND' >> /root/run_apache.sh && \
 chmod 755 /root/run_apache.sh
EXPOSE 80
CMD /root/run_apache.sh
EOF

  # Build our apache container
  sudo docker build -t apache /tmp/

  # Run our apache container
  sudo docker run -d --name apache -p 8889:80 apache
  
  echo "Docker installed successfully. Apache container running at http://localhost:8889"
else
  echo "Docker is already installed."
  
  # Check if apache container exists
  if [ ! "$(sudo docker ps -q -f name=apache)" ]; then
    if [ "$(sudo docker ps -aq -f status=exited -f name=apache)" ]; then
      # Cleanup
      sudo docker rm apache
    fi
    # Build our apache container if needed
    if [[ "$(sudo docker images -q apache 2> /dev/null)" == "" ]]; then
      # Create our Dockerfile
      cat << 'EOF' > /tmp/Dockerfile
FROM ubuntu:18.04
# Install dependencies
RUN apt-get update && \
 apt-get -y install apache2
# Install apache and write hello world message
RUN echo 'Hello World!' > /var/www/html/index.html
# Configure apache
RUN echo '. /etc/apache2/envvars' > /root/run_apache.sh && \
 echo 'mkdir -p /var/run/apache2' >> /root/run_apache.sh && \
 echo 'mkdir -p /var/lock/apache2' >> /root/run_apache.sh && \
 echo '/usr/sbin/apache2 -D FOREGROUND' >> /root/run_apache.sh && \
 chmod 755 /root/run_apache.sh
EXPOSE 80
CMD /root/run_apache.sh
EOF
      # Build our apache container
      sudo docker build -t apache /tmp/
    fi
    # Run our apache container
    sudo docker run -d --name apache -p 8889:80 apache
    echo "Apache container running at http://localhost:8889"
  else
    echo "Apache container is already running."
  fi
fi

🔗 Additional Resources

• Docker Official Website
• Docker Documentation
• Docker Compose Documentation
• Docker Hub - Repository for Docker images
• Docker Best Practices
• Docker Cheat Sheet