What is the difference between docker and virtual machine

The specific difference analysis is as follows:

1. Essential difference

(Recommended tutorial:docker tutorial)

VM (VMware) creates a virtual layer, a virtualized operating system, and a virtualized warehouse based on the host machine and the host machine operating system, and then installs the application;

Container( Docker container), create a Docker engine on the host machine and the host machine operating system, and then install the application based on the engine.

Then the question is, how to run the program without an operating system?

You can create an ubuntu image file in Docker, so that the ubuntu system can be integrated into Docker, and the running applications are all ubuntu applications

2. Differences in use

Size:

Memory occupied by ubuntu in the virtual machine:

Memory occupied by the ubuntu image file in the Docker container:

Startup:

Docker creates the Docker engine on the host machine's operating system and directly calls hardware resources on the host machine's operating system instead of virtualizing the operating system and hardware resources, so the operation speed is fast.

This actually installs an ubuntu virtual machine and pulls a Docker ubuntu image file. You will know after running it. The difference is obvious. It takes more than 2 minutes to open the virtual machine, while Docker only takes 2 minutes. seconds.

Integration:

Docker has better integration than VM.

3. Docker features

1. Quick to get started

Users can "Dockerize" their own programs in just a few minutes. Docker relies on the "copy-on-write" model, which makes it very fast to modify the application. It can be said that it reaches the realm of "the code is changed as you please".

Afterwards, you can create a container to run the application. Most Docker containers start in less than 1 second. Since the overhead of the hypervisor is removed, Docker containers have high performance, and more containers can be run on the same host, allowing users to make full use of system resources as much as possible.

2. Logical classification of responsibilities

Using Docker, developers only need to care about the applications running in the containers, while operation and maintenance personnel only need to care about how to manage the containers. The purpose of Docker's design is to enhance the consistency between the development environment where developers write code and the production environment where applications are deployed. Thereby reducing the kind of "everything is normal during development, it must be an operation and maintenance problem (the test environment is normal, if there is a problem after going online, it must be an operation and maintenance problem)"

3. Fast and efficient The development life cycle

One of the goals of Docker is to shorten the cycle of code from development and testing to deployment and online operation, making your application portable, easy to build, and easy to collaborate. (In layman’s terms, Docker is like a box that can contain many objects. If you need these objects, you can directly take them away from the big box without taking them one by one from the box.)

4) Encourage the use of service-oriented architecture

Docker also encourages service-oriented architecture and microservices architecture. Docker recommends that a single container only runs one application or process, thus forming a distributed application model. Under this model, applications or services can be represented as a series of internally interconnected containers, thus enabling distributed deployment Application, extension or debugging of the application becomes very simple, while also improving the introspection of the program. (Of course, multiple applications can be run in a container)

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