Cicd introduction [easy to understand]

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CI/CD

​ CI/CD The emergence of has changed the way developers and testers release software .

​ Traditional software development and delivery methods are rapidly becoming obsolete . In the past agile Era , Most companies have a monthly software release cycle 、 Every quarter or even every year , And now DevOps Time , Once a week 、 Every day or even many times a day is normal . When SaaS( Software as a service ) This is especially true after becoming the mainstream of the industry , You can easily update your application dynamically , Instead of forcing users to download update components . A lot of times , Users won't even notice what's happening . The development team through the software delivery pipeline （Pipeline） Automation , To shorten the lead time , Most teams have automated processes to examine the code and deploy it to a new environment .

CI What is it? ？

Continuous integration

​ Definition ： Frequently ( Many times a day ) Integrate the code into the trunk .CI It is a method of introducing automation To frequently deliver applications to customers .CI The core concept is continuous integration 、 Continuous delivery and continuous deployment . As a solution for development and operations teams ,CI It mainly aims at the problems caused by integrating new code （ Also known as “ Integrated hell ”）.

​ Continuous integration emphasizes that after developers commit new code , Build immediately and automatically 、（ unit ） test . According to the test results , We can determine whether the new code and the original code can be properly integrated .

The purpose of continuous integration

​ It's about making the product iterate quickly , At the same time, it can maintain high quality **.** 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 .

​ In the process of continuous integration, we attach great importance to automated test verification results , Early warning of possible problems , To ensure that there is no problem with the final merged code .

The role of continuous integration

• The more code inventory is overstocked , The less we can get production inspection , More backlog , The greater the probability of cross infection between codes , Next release （release） The higher the complexity and risk , Continuous integration can guarantee the quality of code submitted by team developers , Reduce the pressure of software release ;
• Any part of continuous integration is done automatically , No need for too much human intervention , It helps to reduce the number of repetitive processes to save time 、 Cost and workload ;
• Find problems in your code early , Solve as soon as possible , The earlier the code is pushed （PUSH） get out , The sooner users can use , Fast is the commercial value ;

characteristic

• It's an automated, periodic integration testing process , Check out code from 、 Compiling and constructing 、 Run the test 、 Result record 、 Test statistics, etc. are all done automatically , No manual intervention required ;
• A dedicated integration server is needed to perform integration builds ;
• Need to be supported by code hosting tools ;

CD What is it? ？

​ CI/CD Medium “CD” Refers to continuous delivery and / Or continue to deploy , These related concepts are sometimes used interchangeably . Both are related to the automation of the subsequent stages of the pipeline , But sometimes they are used alone , Used to illustrate the degree of automation .

​ Continuous delivery （Continuous delivery） refer to , 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 emphasizes , No matter how it's updated , Software can be delivered anytime, anywhere . continued deliver It usually means that developers will automatically error test the application changes and upload them to the repository （ Such as GitHub Or container registry ）, Then the operation and maintenance team will deploy it to the real-time production environment . This aims to solve the problem of poor visibility and communication between development and operation and maintenance teams . therefore , The goal of continuous delivery is to ensure that the amount of work required to deploy new code is minimized .

​ continued Deploy （ Another kind “CD”） It refers to automatically publishing developer changes from the repository to the production environment , For customer use . It is mainly to solve the problem that the manual process reduces the application delivery speed , So that the operation and maintenance team is overloaded . Continuous deployment is based on the advantages of continuous delivery , The automation of the subsequent stages of the pipeline is realized .

​ in the final analysis , We don't have to worry about the semantics , You just need to remember CI/CD It's actually a process （ It is usually expressed as a pipe ）, It is used to realize high continuous automation and continuous monitoring in application development . It varies from case to case , The specific meaning of the term depends on CI/CD The degree of automation of the pipeline . Many companies start by adding CI, And then gradually automate delivery and deployment （ For example, as [ Cloud native application ] Part of ）.

CICD Implementation process The assembly line in the factory is fast 、 automation 、 Produce consumer goods from raw materials in a repeatable way . Again , Software delivery pipeline to fast 、 Automated and repeatable way to generate releases from source . How to complete the overall design of this work is called “ Continuous delivery ”（CD）. The process of starting an assembly line is called “ Continuous integration ”（CI）. The process of ensuring quality is called “ Keep testing ”, The process of making the final product available to users is called “ Continuous deployment ”

Implementation process

​ 1、 The operation and maintenance administrator creates gitlab project , establish Jenkins project

​ 2、 The developers will code Submit to the corresponding gitlab in （ Can be triggered by Branch ）

​ 3、gitlab adopt webhook Trigger corresponding Jenkins project

​ 4、 Get into CI link ： take code Integrated into the standard docker In the mirror , And test ;

​ Successful integration and testing , Upload the integrated image to the warehouse ;

Integration or test failure , The end of this Jenkins, And send the reason to the developer and the operation and maintenance administrator by email .

​ 5、 Get into CD link ：

​ adopt Ansible take CI The successfully integrated image is deployed to all defined machines , And test .

​ If the test passes, complete the deployment , If the test fails, it will determine whether the project is deployed for the first time ;

​ If the project is not deployed for the first time , Roll back to the previous version of the container , And send the reason to the operation and maintenance administrator by email .

If the test fails, it will determine whether the project is deployed for the first time ;

​ If the project is not deployed for the first time , Roll back to the previous version of the container , And send the reason to the operation and maintenance administrator by email .

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