Docker Client

This is the command-line interface (CLI) that allows users to interact with the Docker Daemon. Commands such as docker run, docker build, and docker pull are executed through the Docker Client.

Docker Host

The Docker host provides a complete environment to execute and run applications. It includes Docker daemon, Images, Containers, Networks, and Storage.

Docker Daemon

Docker Daemon: Also known as dockerd, the Docker Daemon runs on the host machine and manages Docker objects like images, containers, networks, and volumes. It listens for Docker API requests and processes them.

Docker Images

Docker Images are read-only templates used to create containers. An image includes everything needed to run an application: code, runtime, libraries, environment variables, and configuration files. Images are built from a Dockerfile, which is a script containing a series of instructions on how to build the image.

• Dockerfile: A text file that contains the commands to assemble a Docker image. Each command in a Dockerfile creates a new layer in the image, contributing to its final form.

Docker Containers

Docker Containers are executable instances of Docker images. Containers are lightweight and portable, providing isolated environments where applications can run. Unlike virtual machines, containers share the host system’s kernel and resources, making them more efficient.

• Isolation: Containers use namespaces and control groups (cgroups) to provide isolation. Namespaces ensure that a container sees its own separate instance of the global system resources, while cgroups limit the resources a container can use.

Docker Networking

Docker Networking allows containers to communicate with each other and with external systems. Docker provides several types of networks:

• Bridge Network: The default network for standalone containers, allowing containers on the same host to communicate.

• Host Network: Removes network isolation between the container and the Docker host, allowing the container to use the host’s network stack directly.

• Overlay Network: Enables communication between containers across multiple Docker hosts, typically used in Docker Swarm.

• Macvlan Network: Assigns a MAC address to each container, making them appear as physical devices on the network.

Docker Storage

1. Data Volumes:

   • Data Volumes create persistent storage.
   • Volumes can be renamed and listed, and you can list the containers associated with a volume.
   • These volumes exist on the host filesystem outside the container’s copy-on-write mechanism, offering efficiency.

2. Data-Volume Containers:

   • A dedicated container hosts a volume.
   • This volume can be mounted to other containers.
   • The volume container is independent of application containers, allowing sharing across multiple containers.

3. Bind Mounts:

   • Bind Mounts allow you to mount any directory from the host machine into a container.
   • Unlike Data Volumes, which reside within the Docker volumes folder, Bind Mounts can use any directory on the host as a volume source.

Docker Registries

Docker registries are essential services for storing and retrieving Docker images. They host repositories that store multiple Docker images, facilitating easy access and distribution across environments. Public registries like Docker Hub and Docker Cloud provide a vast collection of publicly available images, while private registries offer secure repositories for proprietary or sensitive applications. Organizations often set up their own private registries to manage and control access to custom-built images. These registries enable efficient deployment pipelines by ensuring that Docker images can be easily pushed, pulled, and managed with versioning and access control mechanisms in place.