Software development groups that achieve high performance in development and delivery provide a strategic advantage to their business. However, many organizations struggle with delivering software in a timely manner. The set of practices called "continuous delivery" is gaining favor as an important part of the work of delivering new software on time. Continuous delivery defines a set of practices that aim to eliminate mechanical impediments and deliver software with greater velocity to respond to market needs.
Continuous Delivery as a Pipeline
Let's start by outlining what continuous delivery is. One of my favorite definitions comes from Jez Humble of Thoughtworks, whose book is the seminal text on the discipline. He says, "The essence of my philosophy to software delivery is to build software so that it is always in a state where it could be put into production. We call this Continuous Delivery because we are continuously running a deployment pipeline that tests if this software is in a state to be delivered."
Continuous delivery is not defined as continuous deployment, continuous release, or something that only cloud applications need worry about. Continuous delivery uses a set of key principles that involve staging the software development and delivery process. Each stage in the process possesses a distinct set of criteria that must be validated before software can progress to the next stage. These processes leverage automation for testing, software deployment, and promotion. The end result of the stage-based process is the formation of a delivery pipeline through which new software can continuously flow, and as it flows, it is validated to progressively higher levels of quality.
Because continuous delivery is not a tool or product, achieving it is difficult. The approach to a successful continuous delivery process is a holistic one, where software development organizations must align technology, process, people, and values. It means a mindset shift for teams unused to it and, frequently, changes to processes and tools. For continuous delivery to be done properly, it also requires organizational changes. Achieving excellence in continuous delivery isn't easy, but the reward is enormous: Development teams will be able to move at velocities not previously thought possible.
Steps to Continuous Delivery
The overarching concept of continuous delivery is not new; in fact, the first agile principle states, "the highest priority is to satisfy the customer through early and continuous delivery of valuable software." Despite this familiarity, many companies even those committed to agile processes struggle to just get started.
The roadmap to achieve continuous delivery begins with modeling the development and delivery pipeline. Many of today's organizations are formed from disconnected teams. If you want continuous delivery, you need continuous flow from beginning to end.
Achieving continuous flow requires a multi-step approach whereby organizations:
- Model and measure the cycle time in your existing processes
- Identify delays in the process
- Develop action plans to minimize current delays and eliminate potential future delays
Following this process allows organizations to break down the silos between development and operations in order to produce a single, unified pipeline ranging from concept all the way through delivered software.
Continuous delivery is a journey, not something that is achievable overnight, because development organizations must make significant changes, often to technology, process, culture, and people, to implement the full pipeline and these changes take time, often more than a year.
Where should software development organizations start? Here are three fundamental areas where companies should focus their initial efforts.
- Requirements management: Requirements must be decomposed to minimum deliverable units; development plans should be created and organized around incremental delivery.
- Testing/Validation: The QA process has to be empirical, structured and organized, as well as automatable. In addition, good continuous integration is a prerequisite for continuous deployment
- Delivery Mechanics: Start with version control. Reproducibility of software builds is a common practice, however reproducibility of deployment is often a missing element. (For more on this topic, see this recent Dr. Dobb's editorial.) Then, automate delivery. Keep at it until it's a one-click frictionless process.
Barriers to Successful Continuous Delivery
Most software development organizations face what appear to be overwhelming barriers to achieving continuous delivery. They find themselves in this perceived situation because their existing legacy products have been developed without following continuous delivery principles. The good news: They can start now. Companies can begin defining their goals and objectives and put practices in place that allow them to make small gains along the way to their ideal situation.