foreword
Docker provides an innovative approach to standardized delivery , making development, testing, and deployment processes visible, controllable, and credible through pipeline tools. So to sum it up: Docker solves the problem of operating environment and configuration, standardizes the construction process, and facilitates continuous integration and continuous delivery.
Table of contents
3. The development history of Docker:
4. Application scenarios of Docker:
1. Introduction to Docker:
Docker is an open source containerization platform that can use containers to virtualize applications and services. It packages applications and required dependencies into self-contained units called containers so that they can be deployed and run quickly and reliably in any environment. Using Docker, developers can easily build, release, and manage applications regardless of the constraints of the underlying hardware or operating system.
2. The origin of Docker:
Docker was originally developed by dotCloud in 2013 and released as an open source project in March 2013. Its founder is Solomon Hykes, who created Docker in search of a better way to deploy and run applications. He found that virtualization technology has some limitations when deploying applications, such as performance loss and waste of resources. So he developed a new containerization technology, Docker.
3. The development history of Docker:
Since its release, Docker has quickly gained widespread recognition and adoption. Docker achieved 1 million downloads in less than a year and attracted the attention of developers and enterprises from all over the world. In 2014, the Docker company was established to support and promote the Docker platform. Over time, Docker has continued to evolve and improve, adding many new features and capabilities.
4. Application scenarios of Docker:
Docker is widely used in many different application scenarios. It can be used to quickly deploy and scale web applications. Using Docker, developers can package applications and required dependencies into a single container and easily deploy them in different environments. Additionally, Docker can be used to build continuous integration and continuous deployment (CI/CD) pipelines to automate building, testing, and deploying applications.
Docker can also be used in development and test environments. Developers can create a container in their local development environment that includes all development tools and dependencies. This way, they can easily share and reproduce the development environment in different environments. Additionally, Docker can also be used to create a consistent testing environment so that developers and testers can test in the same environment.
5. Advantages of Docker:
Docker has many advantages that make it a favorite containerization platform for developers and operators.
First, Docker provides a lightweight virtualization technology. Compared with traditional virtual machines, Docker containers are more lightweight, start faster, and occupy fewer resources. This makes Docker ideal for deploying and scaling applications in cloud environments.
Second, Docker provides a portable way to deploy. Using Docker, developers can package an application and required dependencies into a single container and easily deploy it in different environments. This allows applications to be consistent across development, test, and production environments, reducing issues caused by environment differences.
In addition, Docker also provides a flexible way to expand. Using Docker, developers can easily deploy and scale containers on different hosts. They can scale up or down the number of containers to accommodate traffic changes based on the needs of the application.
Finally, Docker also provides a simplified and automated way to deploy. With Docker, developers can use a Dockerfile to define and describe an application's environment and dependencies. They can then use Docker Compose or Docker Swarm to deploy and manage multiple containers. This makes the application deployment process simpler and repeatable.
6. Docker architecture:
Docker's architecture consists of three main components: the Docker client, the Docker daemon, and the Docker image.
A Docker client is a command-line tool or graphical interface for users to interact with Docker. It can communicate with the Docker daemon through the Docker API to perform various operations such as creating, starting, stopping, and deleting containers.
The Docker daemon is a background process running on the host, responsible for managing and monitoring the running of Docker. It receives commands from the Docker client and creates, starts, stops, and deletes containers according to the commands. The daemon is also responsible for managing the container's network and storage, as well as other container-related tasks.
A Docker image is a read-only template that contains the filesystem and dependencies needed to run a container. Images can be built from a Dockerfile, which is a text file that contains the steps and instructions needed to build an image. By using images, containers can be quickly created and started, and shared and reproduced in different environments.
7. The principle of Docker:
The principle of Docker is based on some features of the Linux operating system, such as namespaces, control groups, and joint file systems.
Namespaces are an isolation mechanism that isolates processes from the file system. Docker uses different namespaces to isolate containers, such as the PID namespace for isolating processes, and the network namespace for isolating networks.
A control group is a resource limitation and control mechanism that organizes processes into a hierarchy and allocates resources to each component. Docker uses control groups to limit the resource usage of containers, such as CPU, memory, disk, and network.
A union file system is a mechanism for merging different file systems into a single file system. Docker uses a joint file system to build images, which combines multiple layers of file systems into a readable and writable file system. This makes building and distributing images more efficient and flexible.
By using these features, Docker can achieve container isolation, resource constraints, and file system sharing. This allows applications to run in different containers without interfering with each other while maximizing the use of hardware resources
Summarize:
Docker is an open source containerization platform that packages applications and required dependencies into containers so that they can be deployed and run quickly and reliably in any environment. Its founder is Solomon Hykes, first developed by dotCloud, and released as an open source project in 2013.
Since its release, Docker has quickly gained widespread recognition and adoption. Its advantages include lightweight virtualization, portable deployment methods, flexible expansion methods, and simplified and automated deployment processes.
Docker's architecture consists of three main components: the Docker client, the Docker daemon, and the Docker image. The Docker client is used to interact with Docker. The Docker daemon is responsible for managing and monitoring the running of Docker. The Docker image is a read-only template that contains the file system and dependencies required to run the container.
The principle of Docker is based on some features of the Linux operating system, such as namespaces, control groups, and joint file systems. By using these features, Docker achieves container isolation, resource constraints, and file system sharing.
Overall, Docker is a powerful containerization platform that provides an easy, flexible and efficient way to build, release and manage applications. It is widely used in many different application scenarios, providing developers and operators with a better development, testing and deployment experience.