The software delivery lifecycle (SDLC) is a structured process you use to develop, test, and release software. It helps you organize the steps needed to turn an idea into a working application or system. In DevOps, understanding the SDLC is essential because it ensures your software is reliable, efficient, and meets user needs.

Stages of the SDLC

• Planning: define what the software should do and outline the requirements;
• Design: create the architecture and technical specifications for the solution;
• Development: write the code to build the features and functionality;
• Testing: check the software for errors, bugs, and verify it works as intended;
• Deployment: release the software to users or production environments;
• Maintenance: fix issues, update features, and keep the software running smoothly.

Each stage in the SDLC serves a specific purpose and helps you catch problems early, which saves time and resources. In DevOps, following the SDLC also improves collaboration between development and operations teams, making it easier to deliver high-quality software quickly and consistently.

Key Stages of the Software Delivery Lifecycle

The software delivery lifecycle (SDLC) is a structured process that guides software from initial concept to ongoing operation. Each stage is designed to ensure reliable, high-quality software delivery.

Planning

• Define project goals, requirements, and scope;
• Identify resources, timelines, and potential risks;
• Lay the foundation for all future work.

A clear planning stage helps you avoid misunderstandings and sets realistic expectations for the project.

Development

• Write and assemble the code according to specifications;
• Implement features, fix bugs, and create documentation;
• Collaborate with team members for code consistency.

Effective development practices ensure your application meets requirements and is maintainable.

Testing

• Verify that the software functions as intended;
• Identify and resolve defects before deployment;
• Use automated and manual tests to ensure quality.

Thorough testing reduces the risk of failures and increases user satisfaction.

Deployment

• Release the software to production or end users;
• Follow controlled processes to minimize disruption;
• Roll out updates and patches as needed.

Careful deployment ensures that new features and fixes reach users smoothly.

Monitoring

• Track application performance and user activity;
• Detect and respond to issues in real time;
• Gather feedback for future improvements.

Continuous monitoring helps you maintain reliability and quickly address problems after release.

Each stage of the SDLC builds on the last, creating a repeatable process that supports consistent, dependable software delivery.

Example: Adding a New Login Button

Imagine your team needs to add a new "Login" button to your website. Here’s how this feature moves through the software delivery lifecycle (SDLC):

1. Requirement: you discuss with the product owner and agree the button should appear on the homepage;
2. Development: you write the code for the new button in your development environment;
3. Testing: the quality assurance team tests the button in a separate testing environment to make sure it works and does not break anything else;
4. Staging: you deploy the change to a staging environment, which closely matches production, for a final review;
5. Production: after approval, you release the new button to the live website so all users can see it.

This process ensures that every feature is reviewed and tested before reaching real users.