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The difference between Docker and a virtual machine
1. Introduction
Docker is an open source application container engine, based on the Go language and open source under the Apache2.0 protocol.
Docker allows developers to package their applications and dependencies into a lightweight, portable container, which can then be distributed to any popular Linux machine, and can also be virtualized.
The container completely uses the sandbox mechanism, and there will not be any interface between each other (similar to the iPhone app), and more importantly, the performance overhead of the container is extremely low.
Docker has been divided into CE (Community Edition: Community Edition) and EE (Enterprise Edition: Enterprise Edition) since version 17.03. We can use the Community Edition.
Docker官网：Empowering App Development for Developers | Docker
Docker application scenarios
Automated packaging and publishing of web applications.
Automated testing and continuous integration, release.
Deploy and tune databases or other background applications in a service-based environment.
Build your own PaaS environment by compiling or extending an existing OpenShift or Cloud Foundry platform from scratch.
Advantages of Docker
1. Simplified procedure:
Docker enables developers to package their applications and dependencies into a portable container, which can then be distributed to any popular Linux machine, enabling virtualization. Docker has changed the way of virtualization, allowing developers to put their work directly into Docker for management. Convenience is already the biggest advantage of Docker. In the past, tasks that took days or even weeks can be completed in seconds under the processing of Docker containers.
2. Avoid choice phobia:
If you have a phobia of choice, be a senior patient. Then you can use Docker to package your tangle! For example, Docker images; Docker images contain the runtime environment and configuration, so Docker can simplify the deployment of multiple application instances. For example, web applications, background applications, database applications, big data applications such as Hadoop clusters, message queues, etc. can be packaged into an image deployment.
3. Save money:
On the one hand, with the advent of the cloud computing era, developers do not have to configure expensive hardware in pursuit of results. Docker has changed the mindset that high performance must be expensive. The combination of Docker and the cloud makes the cloud space more fully utilized. It not only solves the problem of hardware management, but also changes the way of virtualization.
Docker's architecture
Docker uses a client-server (C/S) architecture pattern, using a remote API to manage and create Docker containers.
Docker containers are created from Docker images.
| Docker container (Container) |
A container is an application or group of applications that run independently. |
| Docker Client (Client) |
The Docker client communicates with the Docker daemon via the command line or other tools using the Docker API ( Redirecting… ). |
| Docker host (Host) |
A physical or virtual machine used to execute Docker daemons and containers. |
| Docker repository (Registry) |
The Docker repository is used to save images, which can be understood as a code repository in code control. Docker Hub ( https://hub.docker.com ) provides a huge collection of images to use. |
| Docker Machine |
Docker Machine is a command-line tool that simplifies Docker installation. Docker can be installed on the corresponding platform, such as VirtualBox, Digital Ocean, Microsoft Azure, through a simple command line. |
The difference between Docker and a virtual machine
Docker is a lightweight virtualization technology that performs better than traditional virtual machines.
The following figure is the architecture of the virtual machine:
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server - represents a real computer.
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Host OS - the operating system of the real computer, eg: Windows, Linux
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Hypervisor - Virtual machine platform, emulates hardware like VMWare, VirtualBox
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Guest OS - an operating system installed on a virtual machine platform, such as CentOS Linux
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App - an application on a virtual machine operating system, such as nginx
The following figure is the architecture of Docker:
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server - represents a real computer.
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Host OS - the operating system of the real computer, eg: Windows, Linux
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Docker Engine - A new generation of virtualization technology that does not require the inclusion of a separate operating system.
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App - All applications now run as Docker containers.
The obvious advantage of this architecture is that there is no need to provide hardware emulation for the virtual machine operating system. All applications work as Docker containers for better performance.
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