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Today, the editor will show you how to understand CI/CD. The knowledge points in the article are introduced in great detail. Friends who feel helpful can browse the content of the article with the editor, hoping to help more friends who want to solve this problem to find the answer to the problem. Follow the editor to learn more about "how to understand CI/CD".

The requirements of modern software development coupled with the complexity of deploying to different infrastructures make creating applications a tedious process. As applications grow on a large scale and the development team becomes more dispersed, the process of producing and releasing software quickly and continuously becomes more difficult.

To solve these problems, the development team began to explore new strategies to automate their build, test, and release processes to help them deploy new production faster. This is the origin of continuous delivery and continuous integration development.

The editor will introduce what CI/CD is and how it can help teams quickly develop and deploy fully tested and reliable software. Before we understand CI/CD and its advantages, we should discuss some of the prerequisite techniques and practices for building these systems.

Automatic build process

During the software development process, the build process converts the code generated by the developer into executable available software. For compiled languages such as Go or C, at this stage, you need to run the source code through the compiler to generate independent binaries. For interpretative languages such as Python or PHP, there are no compilation steps, but the code still needs to be frozen, bound, and packaged for distribution within a specific period of time. These processes are often referred to as "build" or "release" artifacts.

Although developers can build manually, this has many disadvantages. First, context transformation is introduced in the transition from active development to creating builds, forcing developers to stop more productive work to focus on the build process. Second, each developer is making his own artifacts, which can lead to inconsistencies in the build process.

To address these concerns, many development teams have configured automatic build pipelining. These systems monitor the source code repository and automatically start the preconfigured build process when changes are detected. This configuration does not involve too much manpower and ensures that each build process is consistent.

There are many build tools on the market to help users automate these steps. Here is a list of popular build tools in the Java ecosystem:

Ant:Apache Ant is an open source Java library created in 2000. It is the original build tool in the Java domain and is still used frequently today.

Maven:Apache Maven is an automated build tool written primarily for Java projects. Unlike Apache Ant,Maven, which follows the principle that conventions are superior to configuration, only aspects of the build process that deviate from reasonable default values need to be configured.

Gradle: in version 1. 0 launched in 2012, Gradle tried to combine the advantages of Ant and Maven by combining the modern features of Maven without losing the flexibility provided by Ant. The build instructions are written in a dynamic language called Groovy. Although this is a relatively new tool in this area, it has been widely used.

Version control

Most modern software development requires frequent collaboration in a shared code base. The version control system (VCS) is used to help maintain project history, process discrete features in parallel, and resolve conflicting changes. VCS allows projects to easily adopt changes and roll back if problems occur. Developers can work on projects on the local computer and use VCS to manage different development branches.

Each change recorded in VCS is called a commit. Each commit catalogs changes to the code base, and metadata is included, such as a description of viewing the submission history or merging updates.

Figure 1 distributed version control

Although versioning is a valuable tool, it can help manage many different changes in a single-generation code base. But distributed development usually brings challenges. Developing in a separate branch of the code base without regularly merging into a shared integration branch may make it difficult to merge changes later. To avoid this, developers began to adopt continuous integration practices.

Continuous integration (CI)

Continuous integration (CI) is a process that allows developers to integrate their work into shared branches, thereby enhancing collaborative development. Frequent integration helps resolve isolation and reduce the size of each commit to reduce the possibility of merge conflicts.

To encourage CI practice, a powerful tool ecology has been built. These systems integrate VCS libraries to run build scripts and test suites automatically when changes are detected. Integration testing ensures that different component functions are compatible within a group, allowing the team to discover compatible bug as soon as possible. As a result, the builds produced by continuous integration are fully tested and completely reliable.

Figure 2 the process of continuous integration

Continuous delivery and continuous deployment (CD)

Continuous delivery and continuous deployment are two strategies based on building continuous integration. Continuous delivery is an extension of continuous integration that deploys the build from an integrated test suite to a pre-production environment. This allows it to evaluate each build directly in a class production environment, so developers can verify bug fixes or test new features without any additional effort. Once deployed in a staging environment, additional manual and automated testing may be required.

Continuous deployment is a step further. Once the build has passed the automated test in the staging environment, the continuous deployment system will automatically deploy it to the production server. In other words, each build that passes the test is real-time and provides early feedback. This allows the team to constantly release new features and fix bug, backed by the guarantees provided by its testing process.

Figure 3 CI / CD process roadmap

Advantages of CI/CD

Continuous integration, delivery, and deployment have significantly improved the software development process. Some of the main advantages of CI/CD are briefly described below:

Fast feedback loop

For a rapid development cycle, a fast feedback loop is particularly important. In order to receive feedback in real time, the software must reach the end user quickly. CI / CD can provide a platform to achieve this goal by simplifying update production deployments. By requiring each change to be rigorously tested, CI can help reduce the risks associated with each build and thus make it easy for teams to release valuable features to users.

Increase visibility

CI/CD usually refers to the sequence of the steps of the IT process into a pipeline, and the pipeline is visible to the entire IT team (including development, testing, operation and maintenance teams, etc.). As a result, each team member can track the build status in the system and identify any builds that cause the test to fail. Team members can more easily plan the best course of action by learning more about the current state of the code base. This visibility provides a clear answer to the question-"did the changes I submitted break the build?"

Simplify troubleshootin

Although the goal of CI is to integrate and test every change that occurs in the code base, it is safer to make each commit small and merge them into the shared code repository as soon as possible. This makes it easier to identify changes related to the problem when the bug is found. After all, depending on the severity of the problem, the team can choose to roll back or write and submit fixes, thereby reducing the time it takes to resolve the problem in production.

Higher software quality

Automating the build and deployment process not only shortens the development cycle, but also helps the team develop better quality software. Because each change is fully tested and deployed in at least one pre-production environment, the team can deploy the changes to production without concern. However, this can only be achieved if there is good test coverage at all levels of the contemporary code base, from unit testing to more complex system testing.

Fewer integration problems

Because the automated test suite runs on a build that is automatically generated on each commit, integration problems can be detected and fixed as soon as possible. This allows developers to know early on whether the work currently under way may affect their code. It tests the compatibility of code written by different contributors at the beginning, rather than when other problems may arise later.

Have more time to focus on development

The CI/CD system relies on automation to produce builds and migrate new changes through pipelining. Because manual intervention is not required, build and testing no longer take up a large chunk of the development team's time. Developers can then make effective changes to the code base without distractions, because the automation system notifies them if any problems occur during the build process.

Best practices for continuous integration and delivery

Now that we have seen some of the advantages of using CI/CD, we will discuss some guidelines to help you successfully implement these processes.

Responsible for CI / CD pipeline

Developers are not responsible for the code they submit until the changes are deployed in a pre-production environment. This means that developers must ensure that their code is integrated correctly and can be deployed at any time. If the submitted changes violate these requirements, it is the developer's responsibility to submit the fix quickly to avoid affecting the work of others. A build failure should pause the pipeline and prevent submissions that are not involved in fixing the failure, which makes it critical to resolve the build problem quickly.

Ensure consistent deployment

The deployment process does not require manual operation, but the pipeline needs to automate the deployment process to ensure consistency and repeatability. This reduces the possibility of pushing destructive builds into production and helps avoid configurations that are difficult to reproduce and that are not tested.

Submit the code base to version control

It is important to commit each change to version control. This helps the team review all submitted changes and allows the team to simply restore problematic submissions. At the same time, the integrity of configurations, scripts, databases, and documents can be maintained. Without version control, especially when multiple people use the same code base, it is very easy to lose configuration and code changes or mishandle them.

Commit small, incremental changes

Developers must keep in mind that changes must be small. Because waiting for a larger batch of changes will delay test feedback, it will be more difficult to determine the root cause of the problem.

Good test coverage

Since the purpose of CI / CD is to reduce manual testing, the entire code base should have a good automated test coverage to ensure that the software runs as expected. In addition, redundant or outdated tests should be cleaned regularly to avoid affecting the pipeline.

The proportion of different types of tests in the test suite should be similar to the Test Pyramid model. Most tests should be unit tests because they can be executed quickly while having basic functions. In addition, there should be a small number of integration tests to ensure that the components can run successfully together. Finally, a small amount of regression, UI, system, and end-to-end testing should be included at the end of the test cycle to ensure that the build meets all the behavioral requirements of the project. You can use a tool like JaCoCo to determine how many code bases are covered by the test suite.

Figure 4 Test Pyramid

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