Continuous integration (I) brief introduction to basic concepts

Preface

This chapter is mainly about 【 Development model 】 And 【 Continuous integration and delivery 】 Basic concepts

• At present, companies on the market generally use Jenkins Conduct continuous integration operation

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One 、 A brief introduction to the development model

First of all, let me briefly mention 【 Waterfall model 】 and 【 agile development 】 Model

• Waterfall model ： Simply speaking , Just like Factory assembly line equally , After one link is finished, go to the next link （ From design –> Development –> test –> Development and Reform bug–> pre-release –> Production etc. ）, People in all links can manage their own affairs , During the development process, customers can only Through documentation To understand the product

  So its biggest drawback is ： The implementation of downstream work depends heavily on the completion of upstream delivery , Caused a serious waste of human resources .

• Agile development model ： namely Customer demand oriented , Rapid iterative functional development ( Dealing with customers )

  In the early stage of software project construction, it will be divided into Many independent small projects To develop , Everyone has to work at the same time ( No longer rely on upstream ), The biggest feature is that customers will participate in the process of software development , Be able to respond to customers' needs in a timely manner

  Development mode like this , It is more common in government projects , It is based on the needs of customers to carry out rapid iterative development , The most important thing is more than customer communication , Know more about what customers need . Most of the versions released each time are small versions .

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Why mention the development model first ？

• According to my personal understanding, simply say

Because at present, most companies actually implement a 【 agile development 】 Pattern , That model for agile development , Usually the version is based on Small version release Mainly , We need to carry out a quick iteration of the project in a short time , That's for this way of fast iteration , Continuous integration and continuous delivery will inevitably become an important part , It can speed up the delivery of the project , One efficiency of accelerating development and testing

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Two 、 A brief introduction to continuous integration and continuous delivery

Continuous integration （Continuous integration）： That is, frequently （ Many times a day ） Integrate the code into the trunk . Namely Let the product iterate quickly , At the same time, it can maintain high quality . It's mainly in The development phase perform , Its core measure is , Before the code is integrated into the trunk , Must pass automated tests . As long as one test case fails , You can't integrate .

• for instance ： Usually we do UI/API After the deployment of automated use cases , Just develop there Git Submitted the code , It will automatically trigger our use case execution , Then send the test report , In a sense , It's actually a smoke test , But this one is directly and automatically integrated

What are the advantages of continuous integration ？

（1） You can quickly find mistakes . Every time I finish a little update , It's integrated into the backbone , You can quickly find mistakes , It's also easier to get a location error .
 Unlike the waterfall model, when the final product is developed , Before submitting the test , What will be left at that time bug There will be a lot of , It will cost a lot of time 

（2） Prevent branches from departing significantly from the trunk . If not always integrated , The backbone is constantly updated , It will make the integration more difficult , It's even hard to integrate . 
 Usually in the development stage , Different development and different requirements will pull different branches , It will not be closed until all the code tests of this branch have been verified master Branch , Continuous integration 

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Continuous delivery （Continuous delivery）： Frequently put new versions of the software , Deliver to quality team or user , For review . If the review is passed , The code goes into production .

Continuous delivery can be seen as The next step of continuous integration . It can be understood that 【 Pre release stage 】, It emphasizes , No matter how it's updated , Software can be delivered anytime, anywhere .

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Continuous deployment （continuous deployment）： yes The next step in continuous delivery , After the code has passed the review , Automatically deploy to production .

The goal of continuous deployment is , Code is deployable at all times , Can enter the production stage .
The premise of continuous deployment is to automate the completion of tests 、 structure 、 Deployment and other steps .