What is continuous deployment?
Continuous deployment is a strategy for software development and releases in which every code change is automatically run through a pipeline of tests and inspections before being pushed into production.
Continuous deployment eliminates the human safeguards against unproven code in live software. It should only be incorporated when the development and IT teams rigorously adhere to production-ready development practices and thorough testing as well as when they apply sophisticated, real-time monitoring and metrics in production to discover any issues with new software releases.
How does continuous deployment work?
The purpose of continuous deployment is to accelerate development and reduce the time it takes for changes to reach end users.
To apply continuous deployment, a continuous integration (CI) system is typically used to automatically build and test changes to the codebase. Once the changes have passed all tests, they're automatically deployed to a production environment. This can be achieved using deployment pipelines, which automate the process of building, testing and deploying updates. The continuous delivery pipeline includes various steps, such as building the code, running automated tests, deploying to staging environments, testing in those environments and deploying to production.
Continuous deployment relies heavily on automation to ensure that changes are deployed consistently and reliably. Development teams can quickly discover and correct issues, reduce the risk of introducing defects, and ultimately deliver value to end users at a faster pace by continuously deploying code updates.
Benefits of continuous deployment
Continuous delivery offers development teams the following advantages:
- Expedited software delivery. The most significant advantage of continuous development is that it expedites the execution of code changes by eliminating bottlenecks at each stage of the pipeline. The code is executed with minimal downtime, letting end users benefit from new features more quickly because there's no extended wait time of weeks or months for the next release cycle to complete.
- Quicker feedback. More frequent application upgrades result in a shorter feedback loop with the customer. With continuous deployment, a developer or product manager only needs to wait a few minutes to monitor the impact of new changes on user behavior or engagement and modify accordingly. When client behavior indicates the need for a quick pivot or change in approach, the ability to release updates quickly is beneficial. It also aids in detecting issues and shortens the feedback loop for user-facing modifications.
- Reduced development risks. Continuous deployment decreases development risks. When teams integrate consistently and frequently, they considerably reduce potential risks, since they always know the system's current status.
- Reduced manual processes. Continuous deployment encourages engineers to automate as much of the software development and code release process as possible, including release testing. Automation lets developers push new releases more quickly and save time normally spent on manual processes.
- Enhanced collaboration. Continuous deployment encourages teams to provide regular input so the product can be enhanced and improved through iteration.
Continuous deployment vs. continuous delivery
Continuous integration, delivery and deployment are collectively referred to as continuous software development, and they're associated with the Agile and DevOps methodologies. Continuous delivery and deployment originate from continuous integration, a method to develop, build and test new code rapidly with automation so only code that's known to be good becomes part of a software product.
Continuous deployment isn't the same thing as continuous delivery, although the two terms are often confused.
Continuous delivery occurs when developers frequently hand off new code to the quality assurance and operations teams for testing. Continuous delivery usually involves a production-like staging area, and there's often a time lag between a release and when it's reviewed, when changes are manually accepted and when the new code is released to production.
In contrast, continuous deployment doesn't require a staging area for code changes to be manually reviewed and verified. Automated testing is integrated early in the development process and continues throughout all the phases of the release. One of the main benefits of continuous deployment is that there's no time lag between when a code change passes application- and platform-level testing and when it moves into live production.
Both continuous delivery and continuous deployment rely on real-time infrastructure provisioning and application monitoring tools to discover any problems that weren't caught in the testing feedback loops before deployment. Testing and monitoring are more crucial in the continuous deployment process because there's no human intervention for performance verification.
Regulatory compliance or other restrictions can prevent an IT organization from adopting continuous deployment. Other considerations, such as the maturity of DevOps processes and best practices within the IT organization, should also influence the decision of whether to deploy code on a continuous delivery basis, a continuous deployment basis, or some combination of the two approaches based on the application and users.
Continuous deployment tools
Continuous deployment pipelines use tools like those used in continuous delivery, with an enhanced emphasis on code testing prior to and after deployment into production.
The following are some of the most important tools in a continuous deployment workflow:
- Continuous integration tools. CI is a crucial feature of continuous deployment that reduces development bottlenecks when several developers work on the same project. Common tools to automate the building, testing and deployment of code changes include AWS CodeBuild, CircleCI, the open source tool Jenkins and Travis CI.
- Version control systems. Version control, also referred to as revision or source control, facilitates team collaboration regardless of where and when individuals work by increasing the visibility of a project's updates and changes. Version control systems such as Git, Apache Subversion and Mercurial are critical for continuous deployment, as they provide users with a mechanism to track new versions and manage code changes.
- Configuration management tools. Configuration management is the process of ensuring all software and hardware are kept in a consistent state. This can include proper configuration and automation of all servers, networking, storage and software. For configuration and management of infrastructure and applications, tools such as Ansible, Chef and Puppet are used.
- Monitoring and observability tools. Monitoring and incident response for continuous deployment setups should be as close to real time as possible to shorten the time to recovery when there are problems in the code. Tools such as Datadog, Elastic Stack, Grafana, New Relic, Prometheus and Splunk are used for these purposes.
- Containerization and orchestration tools. Some applications can be deployed in containers to isolate updates from the underlying infrastructure. Containerization tools, such as Amazon Elastic Container Service, Docker, Google Kubernetes Engine and Kubernetes, are used to package applications and dependencies in a portable format, making scaling and deployment easier.
- Deployment automation tools. To automate the deployment of code changes to production environments, tools such as AWS CodeDeploy, Azure DevOps and Google Cloud Build are used.
Rollback capabilities are necessary in the deployment tool set so that any unexpected or undesired effects of new code in production can be caught and mitigated quickly. Organizations can rely on canary deployment, sharding, blue/green deployment, feature flags or toggles, and other deployment controls to safeguard against user disruption from continuous deployment.
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