Skip to main content

Docker

Docker is a set of platform as a service (PaaS) products that use OS-level virtualization to deliver software in packages called containers. Containers are isolated from each other and bundle their own software, libraries, and configuration files; they can communicate with each other through well-defined channels. For platform engineering, Docker provides a robust, flexible foundation for developing, shipping, and running applications. This documentation outlines how Docker can be leveraged in platform engineering, covering key concepts, benefits, use cases, and best practices.

info

If you are new to Docker, refer to the official Docker documentation.

Key Concepts​

Docker Containers​

  • Definition: Lightweight, standalone, executable packages that include everything needed to run a piece of software, including the code, runtime, libraries, environment variables, and config files.
  • Isolation: Containers run in a shared OS kernel but are isolated from each other. This ensures that processes running in one container cannot interfere with those running in another.

Docker Images​

  • Definition: A read-only template with instructions for creating a Docker container. It includes the application code, runtime, system tools, libraries, and settings.
  • Layered File System: Images are built in layers, allowing for efficient storage and sharing of common components across multiple images.

Docker Registries​

  • Definition: A storage and content delivery system for named Docker images. It allows users to push and pull images from a central location, facilitating the sharing and distribution of containers.
  • Public and Private Registries: Docker Hub is a public registry that hosts thousands of images, while private registries can be used to store proprietary images.

Dockerfile​

  • Definition: A text document that contains all the commands a user could call on the command line to assemble an image. Using docker build users can create an automated build that executes several command-line instructions in succession.

Benefits​

  • Consistency Across Environments: Docker containers ensure consistency across different development, testing, and production environments, reducing "it works on my machine" problems.
  • Rapid Deployment and Scaling: Docker containers can be started in milliseconds, making it easy to quickly scale out applications.
  • Isolation: Docker ensures applications are isolated and segregated to enhance security.
  • Resource Efficiency: Containers require less hardware resource than traditional or virtual machine environments because they share the host system’s kernel.

Use Cases​

  • Continuous Integration/Continuous Deployment (CI/CD): Docker simplifies the CI/CD pipeline by allowing developers to create isolated environments for each stage of the pipeline, ensuring that software can be released reliably at any time.
  • Microservices Architecture: Docker is ideal for microservices architecture because it allows each service to be packaged into its own container, ensuring that each service is lightweight and can be deployed independently.
  • Development & Testing: Docker provides developers with the ability to create isolated environments to test and debug applications in a production-like environment, ensuring consistency across the development lifecycle.
  • Application Isolation: Docker allows different applications to run on the same server without interfering with each other, making it easier to manage multiple applications.

Best Practices​

  • Use Official Images: Whenever possible, use official Docker images as the base for your containers to ensure security and stability.
  • Keep Images Small: Optimize your Docker images to be as small as possible without sacrificing functionality to reduce deployment times and increase efficiency.
  • Use Tags: Tag your Docker images with specific version numbers or environment names to facilitate rollback and understand which version of the application is running.
  • Security: Regularly scan your Docker images for vulnerabilities, use trusted base images, and follow Docker’s security best practices.
  • Logging and Monitoring: Implement logging and monitoring within your Docker containers to keep track of their health and performance.
  • Immutable Containers: Treat containers as immutable objects and never modify a running container. Instead, update the Dockerfile and redeploy the container.

Conclusion​

Docker is an essential tool for platform engineering, offering a range of features that streamline the development, deployment, and scaling of applications. By understanding and leveraging Docker's capabilities, platform engineers can significantly improve the efficiency, reliability, and scalability of their applications. Following best practices in Docker usage ensures that applications are secure, efficient, and consistent across all environments.