What is Continuous Deployment?
Continuous Deployment (CD) is a software release process, using automated testing to validate that all changes to a codebase are accurate and ready to be deployed autonomously to a production environment. This software release cycle has progressed and advanced over recent years.
A software engineering approach, CD delivers software functionalities frequently through automated deployments.
As a software release process, CD automatically tests, verifies, and pushes new pieces of code into a production environment if they pass the automated tests.
Continuous development is an extension of continuous integration. While continuous integration ensures that bugs are found and fixed, continuous deployment ensures that your customers always have the most up to date software by automatically pushing those code changes out. Continuous deployment ensures you can release updates to your customers quickly and reliably. Contrary to traditional deployment, continuous deployment should happen without any manual intervention. The main aim of continuous deployment is to reduce the lead time of the software changes and hasten its availability to end users.
Many highly successful software companies have implemented continuous deployment and for good reason. When a software developer adds a new line of code into existing software, the changes go through an automated set of tests to verify its functionality and robustness. Once the code passes the automated testing, it is made available to the end users automatically.
The continuous deployment infrastructure then continues to monitor the behavior of the software. If there is any faulty behavior, an automatic mechanism reverts the changes and restores the software into its original state. All this happens through automated systems. The automated testing, deployment, monitoring, and rolling back processes are all part of the continuous deployment pipeline.
Why do Technology Companies Adopt Continuous Deployment?
Continuous deployment ensures that a new feature or bug fix reaches the end user fast. A robust infrastructure for continuous deployment eliminates the manual errors that can happen during testing and deployment. This also enhances the quality of the software and enables companies to scale up their software production. Except for the initial cost, continuous deployment saves money in the long run because there is no need for costly manual testing and no losses incurred by delays.
What Are the Major Steps of Continuous Deployment?
Typically, continuous integration precedes continuous deployment. The developer finishes a piece of code, performs a unit test, and pushes it into a continuous integration pipeline. The code and its dependent packages are built (compiled), and this new piece of code is integrated with the existing software system. The continuous deployment pipeline starts at this point.
Step 1: Testing and Verification
Automated testing of the new code is a crucial step in continuous deployment. Automated testing includes a set of test scenarios that closely resemble real-time use cases. The test suite exercises the new code and passes it through all these use cases. A robust, automated verification system not only tests the functionality of the new code, it also tests non-functional requirements such as performance, security, and usability.
Automated testing ensures that the new code behaves as expected and doesn’t introduce new issues into the software, known as regression issues. Once the new piece of code passes all the automated tests, it is automatically made available to the end users. However, continuous deployment doesn’t end there.
Step 2: Constant Monitoring
In continuous deployment, there is a system to constantly monitor the behavior and performance of the new code in the production environment. Not just the new piece of code, but the entire software system is monitored in real-time. A robust continuous deployment infrastructure triggers alarms if and when the new code causes an issue in the software in the production environment. This may include triggering the testing framework or paging the owner of the code. This monitoring and alerting happens fast and in real time, so that any necessary rollback can occur quickly.
Step 3: Rollback Changes
A robust continuous deployment pipeline should be able to respond to and recover from production issues quickly, efficiently, and sustainably. This is often done by automatically withdrawing the new code changes, known as rolling back changes. The ability to roll back to a stable version of the software is crucial because, more often than not, end users are actively using the software. Related to this roll back process, the “Mean Time to Recovery (MTTR)” is an important metric that measures the maturity of the continuous deployment systems. It’s the time taken from the detection of a failure to the restoration of the software to working condition. The higher the MTTR, the higher the chances of business losses.
Best Practices of Continuous Deployment
In continuous deployment, the development happens in small chunks. That means a developer works on a small part of the feature, and then it is deployed. When the new feature/bug fix is small, it’s easy to follow the test-driven development. Before writing the code, there should be behavioral specifications (specs), documents that describe the expected behavior of the software under different scenarios. Based on this spec, the developer makes a unit test plan, resulting in tighter unit tests and reducing the chance of production issues.
No Manual Deployment
For a continuous deployment system to succeed, developers should refrain from manually building, integrating, or deploying the code. Even if the change seems trivial, manual deployment and live editing the code can create inconsistencies in the continuous deployment pipeline.
Robust Automated Test Framework
One of the key components of continuous deployment is automated testing. The testing frameworks should cover all the possible test scenarios. It should be flexible enough to include new test scenarios. Automated testing should be consistent, and all the test data and results should be checked into a version control system. The automation framework should run with zero manual intervention, from end to end.
Benefits of Continuous Deployment
Shorter Time to Market
One of the most significant advantages of continuous deployment is that it helps new features and fixes reach the market, and your customers, fast. In an increasingly competitive environment, time to market is a crucial metric for success. In traditional manual deployment, there is a considerable delay in testing the code, approvals, and finally releasing the software for the users.
Enhanced Customer Satisfaction
With continuous deployment, software companies can quickly respond to customer feedback. That feedback could be bug reports or requests for new functionality. Whatever the case, as soon as the company develops a new feature or provides a bug fix (usually using continuous integration), the continuous deployment process helps it reach customers fast and therefore enhance customer satisfaction.
No Big Failures
In continuous deployment, developers incrementally add new code. It happens continuously in small chunks. Before committing, the developer tests these changes and documents the results. Also, there are systems that continuously monitor these new changes. The changes are immediately reverted when an issue is reported. In the traditional process of deployment, where a significant feature is released as a big code change, pinpointing the source of an issue is difficult. But with continuous deployment, companies issues are quickly dealt with and big failures are less common.
Increases Efficiency of the Workforce
Continuous deployment automates most of the mundane tasks in software development. The developer doesn’t need to worry about how the code is integrated, deployed, or tested. Engineers can simply concentrate on improving the quality of their work. It also helps to reduce the time it takes to introduce new features to market. Developers now can quickly finish a slice of code and deploy it—no need to wait for big changes.
Continuous Deployment Vs. Continuous Development
In continuous deployment, every step, from code check in to deployment to production environment, is automated. In continuous development, the last step, that is deploying to the production environment, is manual. In continuous development, all steps until the final approval to production are automated. But, for the new code to go into the production environment, manual authentication/gate pass is required. In a nutshell, continuous deployment is an advanced step in terms of automation.
Challenges in Implementing Continuous Deployment
Strong Continuous Integration Framework
For continuous deployment to work, there should be a rock-solid continuous integration framework. This includes the process and workflows for continuous check in of the code, automated build, and testing (manual or automated). This process must be smooth and fail safe. Setting up such a framework is a challenge for many companies. A successful continuous integration needs support from developers, testers, and build engineers.
Invest time in setting up robust systems for continuous integration. Don’t make drastic changes overnight. The continuous integration process should be implemented one step at a time, making sure all the employees are on the same page. Also, provide incentives to teams who show exemplary adherence to continuous integration.
Human and Organizational Challenges
Continuous deployment proposals may face friction from employees and even from customers. Continuous deployment needs a lot of changes in the development and testing process. It takes some time for employees to develop confidence in the continuous deployment pipeline. The same is the case with the customers. Customers might insist on fewer, well-tested releases, fearing that the continuous deployment might disrupt some of the features. Also, from team to team, the maturity of implementation may differ. Some teams might religiously follow continuous deployment paradigms while others may not.
For each stakeholder, find out their pain point in the current development and deployment process. Then, explain to them how continuous deployment is going to alleviate those pain points.
Availability and Cost of Tools and Resources
Continuous deployment needs a lot of tools and software to run smoothly. Purchasing and installing these tools might prove costly. Numerous tools are available on the market for continuous deployment. It’s a challenge to figure out what works and what doesn’t. Some tools may not be compatible with the existing systems of an organization. Also, implementing continuous deployment requires a lot of resources such as servers and computing power. Acquiring these resources and sharing them among the teams might pose another challenge.
Make the software and tools readily available across the organization. Conduct training sessions and help employees with a visual representation of which tool fits where. Choose tools that are easy to use and uses less manual configuration. Create rules for sharing continuous deployment resources.
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