What is docker used for?

Docker is used as a software containerization platform that allows developers to build an application, package it into a container together with its dependent environment, and then easily publish and apply it to any platform.

The use of docker:

As a software containerization platform, Docker allows developers to build applications , package it into a container together with its dependent environment, and then easily publish and apply it to any platform.

1. Thoughts:

• Container

• Standardization

• Isolation

2. Core:

Docker has three cores: image, container, and warehouse.

3. Whale is the operating system.

The application to be delivered is a variety of goods. To put goods of various shapes and sizes on the whale, you have to consider how to place each piece of goods (the supporting environment of the application). It is also necessary to consider whether the goods and goods can overlap (whether the environment the application depends on will conflict).

Nowadays, containers (containers) are used to put each piece of goods in the container, so that the big whales can be placed, stacked and assembled in the same way, saving time and effort.

That is: package it and put it on the whale, and put it on the server. That is, "build-ship-run", so how it runs on your own computer will also run on the server.

4. The process of running a program with docker:

Go to the warehouse and pull the image locally, and then use a command to run the image and turn it into a container.

(1) Image-copied program

Definition:

Docker image can be regarded as a special file In addition to providing the programs, libraries, resources, configuration and other files required for container runtime, the system also contains some configuration parameters (such as anonymous volumes, environment variables, users, etc.) prepared for runtime.

Function:

Similar to a snapshot of a virtual machine, used to create new containers.

Features:

The image does not contain any dynamic data, and its content will not be changed after it is built.

(2) Container-Container

Where the program is run

The image is static, each layer is only readable, and the container It is dynamic, and the application we specify is running in it.

(3) Warehouse - a place where images are stored

A place where images are stored, similar to git

5. Function:

Solve problems caused by inconsistent operating environments. In this way, there will be no situation where "it runs fine locally, but it doesn't work once it's on the server."

Limit the largest CPU to use the memory hard disk, which plays a role in isolation and avoids the situation where "a piece of code creates an infinite loop, fills up the disk, and other programs also hang up."

Summed up in one sentence: Docker’s standardization makes rapid expansion and elastic scaling easy

Recommended related tutorials: docker tutorial

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