117 lines
5.4 KiB
Markdown
117 lines
5.4 KiB
Markdown
---
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stage: Verify
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group: Pipeline Authoring
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
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description: "An overview of Continuous Integration, Continuous Delivery, and Continuous Deployment, as well as an introduction to GitLab CI/CD."
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type: concepts
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---
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# CI/CD concepts **(FREE)**
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With the continuous method of software development, you continuously build,
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test, and deploy iterative code changes. This iterative process helps reduce
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the chance that you develop new code based on buggy or failed previous versions.
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With this method, you strive to have less human intervention or even no intervention at all,
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from the development of new code until its deployment.
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The three primary approaches for the continuous method are:
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- [Continuous Integration](#continuous-integration)
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- [Continuous Delivery](#continuous-delivery)
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- [Continuous Deployment](#continuous-deployment)
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Out-of-the-box management systems can decrease hours spent on maintaining toolchains by 10% or more.
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Watch our ["Mastering continuous software development"](https://about.gitlab.com/webcast/mastering-ci-cd/)
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webcast to learn about continuous methods and how built-in GitLab CI/CD can help you simplify and scale software development.
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- <i class="fa fa-youtube-play youtube" aria-hidden="true"></i>Learn how to: [configure CI/CD](https://www.youtube.com/watch?v=opdLqwz6tcE).
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- [Make the case for CI/CD in your organization](https://about.gitlab.com/devops-tools/github-vs-gitlab/).
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- Learn how [Verizon reduced rebuilds](https://about.gitlab.com/blog/2019/02/14/verizon-customer-story/) from 30 days to under 8 hours with GitLab.
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## Continuous Integration
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Consider an application that has its code stored in a Git
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repository in GitLab. Developers push code changes every day,
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multiple times a day. For every push to the repository, you
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can create a set of scripts to build and test your application
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automatically. These scripts help decrease the chances that you introduce errors in your application.
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This practice is known as [Continuous Integration](https://en.wikipedia.org/wiki/Continuous_integration).
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Each change submitted to an application, even to development branches,
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is built and tested automatically and continuously. These tests ensure the
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changes pass all tests, guidelines, and code compliance
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standards you established for your application.
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[GitLab itself](https://gitlab.com/gitlab-org/gitlab) is an
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example of a project that uses Continuous Integration as a software
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development method. For every push to the project, a set
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of checks run against the code.
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## Continuous Delivery
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[Continuous Delivery](https://continuousdelivery.com/) is a step
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beyond Continuous Integration. Not only is your application
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built and tested each time a code change is pushed to the codebase,
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the application is also deployed continuously. However, with continuous
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delivery, you trigger the deployments manually.
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Continuous Delivery checks the code automatically, but it requires
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human intervention to manually and strategically trigger the deployment
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of the changes.
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## Continuous Deployment
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[Continuous Deployment](https://www.airpair.com/continuous-deployment/posts/continuous-deployment-for-practical-people)
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is another step beyond Continuous Integration, similar to
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Continuous Delivery. The difference is that instead of deploying your
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application manually, you set it to be deployed automatically.
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Human intervention is not required.
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## GitLab CI/CD
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[GitLab CI/CD](../quick_start/index.md) is the part of GitLab that you use
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for all of the continuous methods (Continuous Integration,
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Delivery, and Deployment). With GitLab CI/CD, you can test, build,
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and publish your software with no third-party application or integration needed.
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<i class="fa fa-youtube-play youtube" aria-hidden="true"></i>
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For an overview, see [Introduction to GitLab CI/CD](https://www.youtube.com/watch?v=l5705U8s_nQ&t=397) from an April 2020 GitLab meetup.
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### GitLab CI/CD workflow
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GitLab CI/CD fits in a common development workflow.
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You can start by discussing a code implementation in an issue
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and working locally on your proposed changes. Then you can push your
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commits to a feature branch in a remote repository that's hosted in GitLab.
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The push triggers the CI/CD pipeline for your project. Then, GitLab CI/CD:
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- Runs automated scripts (sequentially or in parallel) to:
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- Build and test your application.
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- Preview the changes in a Review App, the same as you
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would see on your `localhost`.
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After the implementation works as expected:
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- Get your code reviewed and approved.
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- Merge the feature branch into the default branch.
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- GitLab CI/CD deploys your changes automatically to a production environment.
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If something goes wrong, you can roll back your changes.
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This workflow shows the major steps in the GitLab process.
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You don't need any external tools to deliver your software and
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you can visualize all the steps in the GitLab UI.
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### A deeper look into the CI/CD workflow
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If you look deeper into the workflow, you can see
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the features available in GitLab at each stage of the DevOps
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lifecycle.
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<i class="fa fa-youtube-play youtube" aria-hidden="true"></i>
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[Get a deeper look at GitLab CI/CD](https://youtu.be/l5705U8s_nQ?t=369).
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