{"id":27000,"date":"2022-10-03T14:03:38","date_gmt":"2022-10-03T14:03:38","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=27000"},"modified":"2025-07-12T05:41:39","modified_gmt":"2025-07-12T05:41:39","slug":"tutorial-on-docker-architecture-its-components-and-how-it-works","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/tutorial-on-docker-architecture-its-components-and-how-it-works\/","title":{"rendered":"Docker Tutorials: Docker Architecture and How it works?"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

Docker architecture consists of several components that work together to provide a platform for building, shipping, and running containers. These components include:<\/p>\n\n\n\n

    \n
  1. Docker Engine: This is the core component of Docker, and it is responsible for building and running containers. The Docker Engine provides a REST API for interacting with containers, as well as a command-line interface for managing containers.<\/li>\n\n\n\n
  2. Docker Images: Docker images are snapshots of a container that can be used to launch new containers. Images are stored in a registry, such as Docker Hub or a private registry, and can be pulled down to a local machine for use.<\/li>\n\n\n\n
  3. Docker Registries: Docker registries are where Docker images are stored and distributed. Docker Hub is a public registry that is free to use, but organizations can also set up their own private registries to store and distribute images.<\/li>\n\n\n\n
  4. Docker Containers: Docker containers are isolated environments that run applications. Containers are built from images and can be launched on any host that has the Docker Engine installed.<\/li>\n\n\n\n
  5. Docker Compose: Docker Compose is a tool for defining and running multi-container applications using a YAML file. It allows developers to define the services that make up an application, as well as the relationships between those services, and then start and stop the entire application with a single command.<\/li>\n\n\n\n
  6. Docker Swarm: Docker Swarm is a native clustering solution for Docker that provides high-availability and scalability for containers. Swarm allows administrators to manage a swarm of Docker nodes as a single virtual host, making it easier to deploy and manage containers at scale.<\/li>\n<\/ol>\n\n\n\n

    In summary, Docker architecture consists of several components, including the Docker Engine, Docker Images, Docker Registries, Docker Containers, Docker Compose, and Docker Swarm. These components work together to provide a platform for building, shipping, and running containers.<\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    What is Docker Workflow?<\/h2>\n\n\n\n
    \"\"<\/figure>\n\n\n\n

    The Docker workflow involves several steps to build, package, and run applications as containers. The basic steps are as follows:<\/p>\n\n\n\n

      \n
    1. Writing Dockerfiles: A Dockerfile is a script that contains instructions for building a Docker image. It specifies the base image to use, the application code to include, and the environment variables to set.<\/li>\n\n\n\n
    2. Building Docker Images: Docker images are built from Dockerfiles using the “docker build” command. The build process follows the instructions in the Dockerfile to create a new image that includes the application code and its dependencies.<\/li>\n\n\n\n
    3. Storing Docker Images: Docker images can be stored in a Docker registry, such as Docker Hub or a private registry. Docker images are stored as layers, making it possible to share images between different projects and build new images from existing images.<\/li>\n\n\n\n
    4. Running Docker Containers: Docker containers are launched from Docker images using the “docker run” command. Containers are isolated environments that run applications, and they can be launched on any host that has the Docker Engine installed.<\/li>\n\n\n\n
    5. Managing Docker Containers: Docker provides several tools for managing containers, including the “docker ps” command to list running containers, the “docker stop” command to stop containers, and the “docker rm” command to remove containers.<\/li>\n\n\n\n
    6. Deploying Docker Containers: Docker containers can be deployed to a variety of environments, including physical servers, virtual machines, cloud platforms, and more. Docker Compose and Docker Swarm are two tools that can be used to deploy and manage containers at scale.<\/li>\n<\/ol>\n\n\n\n

      In summary, the Docker workflow involves several steps, including writing Dockerfiles, building Docker images, storing Docker images, running Docker containers, managing Docker containers, and deploying Docker containers. The Docker platform provides a set of tools for building, packaging, and running applications as containers, making it easier to deploy and manage applications at scale.<\/p>\n\n\n\n

      Docker CLI (docker)<\/h2>\n\n\n\n

      \/usr\/bin\/docker<\/code><\/p>\n\n\n\n

      Docker is used as a reference to the whole set of docker tools and at the beginning, it was a monolith. But now docker-cli<\/code> is only responsible for user-friendly communication with docker.<\/p>\n\n\n\n

      So the command\u2019s like docker build ...<\/code> docker run ...<\/code> are handled by Docker CLI and result in the invocation of dockerd<\/strong> API.<\/p>\n\n\n\n

      Dockerd<\/h2>\n\n\n\n

      \/usr\/bin\/dockerd<\/code><\/p>\n\n\n\n

      The Docker daemon – dockerd<\/strong> listens for Docker API requests and manages the host\u2019s Container life-cycles by utilizing contanerd<\/strong><\/p>\n\n\n\n

      dockerd<\/code> can listen for Docker Engine API requests via three different types of Socket: unix, tcp, and fd. By default, a unix domain socket is created at \/var\/run\/docker.sock<\/code>, requiring either root permission, or docker group membership. On Systemd<\/a> based systems, you can communicate with the daemon via Systemd socket activation, use dockerd -H fd:\/\/<\/code>.<\/p>\n\n\n\n

      There are many configuration options<\/a> for the daemon, which are worth checking if you work with docker (dockerd).<\/p>\n\n\n\n

      My impression is that dockerd<\/code> is here to serve all the features of Docker (or Docker EE) platform, while actual container life-cycle management is \u201coutsourced\u201d to containerd<\/strong>.<\/p>\n\n\n\n

      Containerd<\/h2>\n\n\n\n

      \/usr\/bin\/docker-containerd<\/code><\/p>\n\n\n\n

      containerd<\/code> was introduced in Docker 1.11 and since then took the main responsibility of managing containers life-cycle. containerd<\/code> is the executor for containers<\/em>, but has a wider scope than just executing<\/em> containers. So it also takes care of:<\/p>\n\n\n\n