"Shift left" in DevOps is a practice that aims to increase collaboration, feedback, and testing earlier in the software development lifecycle. It means tasks traditionally performed towards the end of the development process, such as testing, monitoring, and security, are performed at earlier stages to identify issues more rapidly and resolve them more efficiently.
The concept of shifting left is inspired by the idea that the earlier you identify and correct issues in the development process, the less costly and time-consuming they become. This can be represented as follows:
Cost of Issue Resolution = f(time)
As ‘time‘ increases (i.e., the issue is detected later in the development cycle), the ‘cost‘ of issue resolution goes up.
The term "shifting left" comes from the visual representation of the software development lifecycle. In a traditional timeline representation, a project moves from left (initial stages) to right (later stages):
Start -> Design -> Development -> Testing -> Deployment -> EndShifting left refers to moving tasks and responsibilities earlier in the lifecycle:
Start -> Design -> Testing -> Development -> Deployment -> EndIn practice, this often involves a more comprehensive and integrated approach to:
1. **Collaboration**: Encourage cross-functional teams to work together from the beginning of a project. This may include developers, QA, operations, and security teams.
2. **Continuous Integration**: Merge code changes regularly and trigger automated builds and tests to catch issues early.
3. **Test Automation**: Automate key tests, such as unit, integration, and performance tests, to perform more rapid and frequent testing.
4. **Continuous Delivery**: Establish a reliable pipeline to build, test, and release software incrementally.
5. **Monitoring and Feedback**: Gather feedback and monitor performance metrics at every stage to ensure a proactive approach to issue identification and resolution.
The benefits of adopting a shift-left approach in DevOps include:
- Faster detection of issues, reducing cost and effort of fixing them
- Improved collaboration and communication within cross-functional team
- Shorter development cycles and time-to-market
- Higher quality software and better user experience
- Enhanced security by considering it throughout the development process
In summary, shifting left in DevOps is about emphasizing collaboration, testing, monitoring, and security early in the software development lifecycle to produce more reliable and maintainable software while reducing the cost and time required to fix issues.