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Docker and Docker Compose: A Comprehensive Overview and Usage Guide

GOOVER DAILY REPORT June 23, 2024
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TABLE OF CONTENTS

  1. Summary
  2. Introduction to Docker
  3. Getting Started with Docker
  4. Understanding Docker Components
  5. Working with Docker
  6. Key Docker Commands
  7. Introduction to Docker Compose
  8. Key Docker Compose Commands
  9. Comparing Docker and Docker Compose
  10. Conclusion

1. Summary

  • The report titled 'Docker and Docker Compose: A Comprehensive Overview and Usage Guide' provides an in-depth exploration of Docker and Docker Compose, shedding light on their primary components, installation processes, critical commands, and practical applications. The purpose of the report is to educate readers on effectively using Docker for containerization and Docker Compose for managing multi-container applications. Key findings include step-by-step installation guides for different operating systems, detailed explanations of essential Docker commands, and the comparison between Docker and Docker Compose. By reading this guide, users can learn how to install Docker on both Windows and Ubuntu, understand Docker's architecture, and execute core Docker commands to manage applications efficiently.

2. Introduction to Docker

  • 2-1. What is Docker?

  • Docker is a platform that lets programmers bundle applications and add various dependencies into containers. It offers a standardized approach to writing, testing, and deploying code. Docker can help perform the work of a virtual machine by enabling portability of various project environments. Released in 2013, it is open-source and available for different platforms like Windows, macOS, and Linux. Docker uses containerization technology to create and deploy applications in a consistent and isolated environment, utilizing a client-server architecture.

  • 2-2. Benefits of Docker

  • Docker provides several advantages, including improved developer productivity, increased application portability, efficient resource utilization, and simplified deployment and scaling of applications. Docker reduces the size of development environments by providing a smaller part of the OS via containers. It allows different teams to work on the same project seamlessly and enables containers to be deployed on any physical or virtual machine and in the cloud. Additionally, Docker containers are lightweight and make it easy to scale applications. With Docker, you save memory and resources compared to traditional virtual machines, as containers share the host OS kernel and do not require a separate guest OS.

  • 2-3. Key Components of Docker

  • The three main primary concepts of Docker are Docker Engine, Docker Container, and Docker Image. The Docker Engine, also known as Docker Daemon, is the core component of the Docker platform responsible for running and managing Docker containers. Docker Containers are built from container images; they are a standard unit of software that packages up the code and all required dependencies needed to run an application on different platforms, fully isolating them. A Docker Image contains everything a container needs to run, including the application code, libraries, dependencies, and the operating system it needs. Docker also includes other components such as Docker Hub, Docker Desktop, and Docker Networking.

3. Getting Started with Docker

  • 3-1. Installation on Windows

  • Docker installation on Windows involves several steps and prerequisites. To install Docker, users must have a Windows 10 Pro, Enterprise, Education version 1909 or higher, or Windows 11 with a 64-bit operating system. The necessary system requirements include at least 4GB RAM and a 64-bit processor with hardware virtualization enabled in BIOS settings. Hyper-V, WSL 2, and Container features must also be enabled in Windows. The installation steps are as follows: 1. Download Docker Desktop from https://docs.docker.com/docker-for-windows/install/. 2. Run the Docker Desktop Installer.exe file. 3. Enable Hyper-V Windows Feature during the configuration process. 4. Follow the on-screen instructions to complete the installation. 5. Restart the computer after the installation is complete. Once installed, Docker Desktop must be manually started from the desktop search results. The tool offers an onboarding tutorial explaining how to build a Docker image and run a container. Users can verify the installation by opening Docker CLI and running the 'docker version' command. Additional instructions are provided for starting Docker Desktop, adding user accounts to the Docker user group, and verifying the Docker installation. For instance, to add a user to the Docker group, users must run 'net localgroup docker-users /add'. Verification commands include 'docker run' and 'docker version'. Docker also provides updates and new features, which users can install from the Docker Desktop settings. Uninstallation can be done through the Windows Start menu under Settings > Apps > Apps & features.

  • 3-2. Installation on Ubuntu

  • Installing Docker on Ubuntu requires a 64-bit version of Ubuntu Lunar 23.04, Ubuntu Kinetic 22.10, Ubuntu Jammy 22.04 (LTS), or Ubuntu Focal 20.04 (LTS). The setup involves the following steps: 1. Remove any old Docker versions using 'sudo apt-get remove docker docker-engine docker.io'. 2. Update the software package list with 'sudo apt-get update'. 3. Install Docker using 'sudo apt install docker.io'. Choose 'y' when prompted. 4. Install dependency packages with 'sudo snap install docker'. 5. Check the installed Docker version with 'docker version'. 6. Run a test Docker image using 'sudo docker run hello-world'. For users to run Docker commands without 'sudo', they need to add themselves to the Docker group: 1. Create the Docker group if it does not exist using 'sudo groupadd docker'. 2. Add the user to the Docker group with 'sudo usermod -aG docker $USER'. 3. Restart the computer for the changes to take effect. Managing Docker containers involves various commands to list, start, stop, and commit changes. Examples include 'docker ps' for listing containers, 'docker run [OPTIONS] IMAGE[:TAG]' to start a container, and 'docker stop [CONTAINER]' to stop a container. Changes can be committed to make new images using 'docker commit [CONTAINER_ID] [new_image_name]'. Additional commands are provided for pulling Docker images, managing volumes, and setting up Docker networks to ensure data durability and efficient container management.

  • 3-3. Verifying Docker Installation

  • To verify the successful installation of Docker, users can follow these steps: On Windows: - Open Docker CLI and run 'docker version' to check the version details. - Use 'docker run' command to verify running capabilities. On Ubuntu: - Use 'docker version' to verify the Docker installation and version. - Run 'sudo docker run hello-world' to pull a test image and check the Docker setup. - Confirm the presence of the Docker image using 'docker images'. Additional verification steps include checking for updates and new features via Docker Desktop settings and testing command functionalities on the command line or PowerShell. Users can also verify the Docker environment by using built-in tutorials and quick start guides provided by Docker.

4. Understanding Docker Components

  • 4-1. Docker Client and Server

  • The Docker client and server together form the core interaction model of Docker. The client sends commands to the Docker daemon, which then executes these commands. The communication between the client and daemon is facilitated by a REST API. The daemon listens for instructions from the client to manage Docker containers, images, and networks.

  • 4-2. Docker Image

  • A Docker image is a lightweight, standalone, and executable software package that includes everything needed to run a piece of software, such as the code, runtime, system tools, libraries, and settings. Docker images are built from a Dockerfile using the 'docker build' command and can be stored in a Docker registry for easy distribution.

  • 4-3. Docker Registry

  • A Docker registry is a centralized location where Docker images are stored, managed, and distributed. Popular Docker registries include Docker Hub, which is public, and private registries that can be set up for internal use. Registries use commands like 'docker pull' to retrieve images and 'docker push' to upload images.

  • 4-4. Docker Container

  • Docker containers are executable instances of Docker images. Each container is isolated and contains the application along with all its dependencies. Containers can be started, stopped, moved, and deleted using Docker commands, and they provide a consistent environment for running applications across different systems.

5. Working with Docker

  • 5-1. Building Docker Images

  • Building Docker images is a crucial part of using Docker effectively. According to the document 'What is Dockerfile and How to Create a Dockerfile in 2024', Dockerfiles are instrumental in this process. A Dockerfile is a simple text file with instructions to build Docker images. The Dockerfile syntax includes commands like FROM to create a layer from a specified image, PULL to add files from a Docker repository, RUN to build the container, and CMD to specify the command to run within the container. Example Dockerfile commands include ENTRYPOINT, ADD, ENV, and MAINTAINER, each serving specific purposes in the image-building process. The document emphasizes the exponential growth in the demand for Docker tools, predicting a rise in market value from USD 217 million to USD 993 million by 2024, underscoring the importance of mastering Dockerfile usage.

  • 5-2. Managing Containers

  • Managing Docker containers involves creating, running, and monitoring containers built from Docker images. The document ‘What is Dockerfile and How to Create a Dockerfile in 2024’ provides a step-by-step guide on creating a new Docker container from an image. For example, to create a container named 'simplilearn' from an image named 'simpli_docker', the command used is `docker run --name simplilearn simpli_docker`. This process includes verifying the Docker image with `docker images` and running the container with `docker run`. The document details various common commands and configurations like ENTRYPOINT and ENV, which are essential for managing containers effectively.

  • 5-3. Dockerfile Syntax and Usage

  • Understanding Dockerfile syntax is fundamental for building and managing Docker containers. The document ‘What is Dockerfile and How to Create a Dockerfile in 2024’ delineates the structure and common commands in a Dockerfile. The syntax includes comments marked by `#`, and command instructions followed by arguments. Key Dockerfile commands include `FROM`, `RUN`, `CMD`, `ADD`, and `ENTRYPOINT`, each playing a specific role in the image-building process. For instance, the `FROM` command creates a layer from an existing image, while the `RUN` command builds the required application dependencies. The document also provides practical examples such as using the `ENTRYPOINT` command to set the default application along with its parameters and the `ADD` command to copy files into the Docker image. Comprehensive knowledge of these commands ensures efficient automation of software deployment in containers.

  • 5-4. Docker Networking

  • Docker networking is essential for enabling containers to communicate with each other. The document 'Docker compose | Wener Live & Life' discusses various options in Docker Compose that facilitate networking between containers. For instance, it explains the use of the `ports` section to map container ports to host ports, enabling external access to container services. Additionally, the `networks` section in Docker Compose defines networks for Docker containers, specifying properties like IP addresses, DNS settings, and network driver types. Commands and configurations such as `network_mode`, `dns`, `dns_opt`, and `dns_search` are outlined to enhance network management within Docker. The functionality offered by Docker Compose for network configuration highlights its importance in operating complex multi-container applications.

6. Key Docker Commands

  • 6-1. Basic Commands

  • The following commands form the foundation of working with Docker: - `docker build`: This command is used to create a Docker image based on the Dockerfile. - `docker run`: Creates and runs a container from an image. - `docker images`: Lists all Docker images available on the machine. - `docker ps`: Shows running containers. - `docker rm`: Removes a container from the machine. - `docker start`: Starts a container. - `docker stop`: Stops a container. - `docker commit`: Commits changes to a Docker image. - `docker tag`: Adds a name to a Docker image.

  • 6-2. Container Management Commands

  • To manage Docker containers effectively, the following commands are essential: - `docker ps`: This command lists all currently running containers. It's useful to check the status of containers and confirm which ones are active. - `docker start [container_id]`: Starts an existing container. - `docker stop [container_id]`: Stops a running container. This is essential for managing resources and stopping processes that are no longer needed. - `docker rm [container_id]`: Removes a container from the machine. This command is used to clean up containers that are no longer in use. - `docker commit [container_id] [new_image_name]`: Commits changes made to a container to create a new image.

  • 6-3. Image Management Commands

  • Managing Docker images involves several key commands: - `docker build -t [image_name] .`: Builds a Docker image from a Dockerfile in the current directory. The `-t` flag tags the image with a name. - `docker images`: Lists all Docker images available on the system. - `docker rmi [image_id]`: Removes a Docker image by its ID. This is useful for cleaning up unused or outdated images. - `docker pull [repository_name]`: Pulls an image from a Docker registry, such as Docker Hub. This is essential for obtaining pre-built images. - `docker push [repository_name]`: Pushes an image to a Docker registry. This is useful for sharing custom images.

7. Introduction to Docker Compose

  • 7-1. What is Docker Compose?

  • Docker Compose is a tool used for defining and running multi-container Docker applications. It uses a YAML file to configure an application's services. With the configurations defined in a docker-compose.yml file, users can deploy and manage multiple containers simultaneously, ensuring seamless interactions among them.

  • 7-2. Setting Up Docker Compose

  • Setting up Docker Compose involves a few key steps. First, ensure Docker is installed on your machine. Then, download Docker Compose from the official Docker website or through a package manager, depending on your operating system. On Windows, Docker Compose can be installed as part of Docker Desktop, which includes all the necessary components. On Ubuntu, it can be installed using apt. A typical command might look like: `sudo apt install docker-compose`. Once installed, Docker Compose can be verified by running `docker-compose --version` in the command line.

  • 7-3. Examples of docker-compose.yml

  • The docker-compose.yml file is central to using Docker Compose. It defines the services, networks, and volumes for a multi-container application. For example, a simple docker-compose.yml file might look like this: ```yaml version: '3.8' services: web: image: 'nginx:alpine' ports: - '8080:80' db: image: 'redis:alpine' ``` This configuration defines two services: `web`, which runs an Nginx server, and `db`, which runs a Redis server. The Nginx server is exposed on port 8080 of the host machine, mapped to port 80 inside the container.

8. Key Docker Compose Commands

  • 8-1. Starting and Stopping Services

  • To start Docker Compose services, use the 'docker-compose up' command. This command reads the docker-compose.yml file and starts the specified services. To stop the services, use the 'docker-compose down' command, which stops and removes the containers, networks, and volumes created by 'docker-compose up'.

  • 8-2. Building and Pulling Images

  • Building and pulling images are essential for preparing the environment before running services. The 'docker-compose build' command builds images specified in the compose file, while 'docker-compose pull' pulls the service images from the registry. Additionally, the 'build' keyword in the docker-compose.yml file allows specifying context and Dockerfile parameters for the build process.

  • 8-3. Viewing Logs and Executing Commands

  • Docker Compose provides commands for log management and command execution. The 'docker-compose logs' command displays the output from services, useful for debugging and monitoring. You can also use 'docker-compose exec' to execute arbitrary commands in the running service containers, providing flexibility for administrative tasks and troubleshooting.

9. Comparing Docker and Docker Compose

  • 9-1. Differentiating Docker and Docker Compose

  • Docker and Docker Compose serve different but complementary roles in containerized application management. Docker provides the core functionality of containerization, allowing applications to run in isolated environments called containers, which can be deployed consistently across different environments. Docker includes various components such as Docker Engine, Docker Hub, Docker Images, and Docker Containers. Docker Compose, on the other hand, is a tool specifically designed for defining and running multi-container Docker applications. It allows for the use of a YAML file to configure application services, making it easier to manage multi-container environments by specifying how the containers should run together. Key benefits of Docker Compose include the ability to easily set up and share multi-container environments, simplifying the workflow for developers working on complex applications with multiple interconnected services.

  • 9-2. Use Cases for Docker vs Docker Compose

  • Docker is primarily used to create, deploy, and run applications in containers. It is beneficial in scenarios requiring isolated environments for application deployment, ensuring consistency across different stages of development, testing, and production. Docker excels in managing individual containers with specific service requirements, facilitating high-velocity innovation by ensuring applications run efficiently in various environments. Docker Compose is advantageous for multi-container environments, particularly useful for applications requiring multiple interconnected services. Its configuration is managed through a YAML file, allowing easy setup and testing of complex applications. Developers use Docker Compose to define all service dependencies (such as databases, caches, and web services) in a single, unified file, making it highly effective for local development and continuous integration/continuous deployment (CI/CD) pipelines. This attribute simplifies the orchestration and management of multiple Docker containers, enhancing productivity and operational efficiency in development workflows.

10. Conclusion

  • This report underscores the significance of both Docker and Docker Compose in the realm of containerized application management. The key finding is the differentiation between Docker’s ability to handle individual containerized environments and Docker Compose’s capacity for orchestrating multi-container setups through simple YAML configurations. Docker is lauded for its benefits in improving application portability and resource utilization, while Docker Compose is praised for its simplicity in managing complex, interconnected applications. However, the report acknowledges limitations such as the necessity for detailed technical knowledge and the initial setup complexity. Future prospects suggest that advanced orchestration tools like Kubernetes could be a valuable extension to this foundational knowledge, offering greater scalability and deployment capabilities. The practical application of these insights will be instrumental in enhancing development and deployment workflows, making the combination of Docker and Docker Compose a powerful asset in modern software development.

11. Glossary

  • 11-1. Docker [Technology]

  • Docker is a platform for developing, shipping, and running applications inside containers. It allows developers to bundle applications with all necessary dependencies, ensuring consistent environments across different stages of development and production.

  • 11-2. Docker Compose [Technology]

  • Docker Compose is a tool for defining and running multi-container Docker applications. It uses a YAML file to configure the application's services, networks, and volumes, allowing for efficient management of complex setups.

12. Source Documents