Progressive Delivery with Feature Flags: Getting Started

In the realm of Continuous Delivery (CD), where the objective is to ensure that software is always in a deployable state, there is still significant value in not exposing all users to new capabilities immediately. Progressive Delivery leverages this principle by gradually rolling out changes to a subset of users, testing in production, gathering feedback, and then expanding the release based on the results.

What is Progressive Delivery?

Combining both progressive deployment and progressive release, we achieve Progressive Delivery—our preferred way to deliver software to customers confidently and iteratively, whether it’s a one-line bug fix or a complex new feature. This ensures that our changes are not only technically sound, but also solve problems in a meaningful way for our users. 

To sum this up with an equation:

Progressive Delivery = Progressive Deployment + Progressive Release

Progressive Deployment vs Progressive Delivery

Progressive deployment involves deploying a new version of software to a small percentage of users initially. This approach helps reduce the risk of introducing bugs or issues for all users when rolling out a new version of our application. One common technique used for this purpose is canary deployment. Various technologies support canary deployments. For instance, at Unleash, we use a custom-built Kubernetes operator to manage deployment channels.

 

At Unleash, we categorize our customers into groups such as demo users, early Pro plan users, established Pro plan users, and Enterprise plan users, deploying the new version to each group at a different pace. With each deployment, every customer in a channel gets all new code created since the last deployment. Charity Majors likens deployment to a chainsaw, emphasizing its broad nature, compared to a scalpel-like feature flag explored below.

After each deployment, we can observe application stability and the impact of changes, such as one-liner bug fixes or trivial code changes (e.g. automated refactorings). For very simple changes, deployment and release can be the same thing. However, we don’t want to use deployment as a release mechanism for more complex features and code changes where the probability and impact of issues are high.

Progressive Release vs Progressive Delivery

Beyond deployment, we use feature flags (yes, we use Unleash to build Unleash) to control which customers can access individual new features at runtime without needing a code deployment. This practice of progressive release allows us to gradually expose features. This enables us to validate the solution meets users expectations and is performant in real-world scenarios.

In each new deployment, all code paths are physically in production, but we don’t enable them for every customer. This decouples deployment (code being in production) from release (code being available to users). Using Charity Majors’ metaphor again, while deployment is a chainsaw, progressive release is a powerful scalpel, offering precise control over feature exposure.

Why Progressive Delivery?

Progressive Delivery offer three main benefits over standard CI/CD or traditional batch updates:

• Live testing
• Risk mitigation
• Improved user experience

Live testing

When working on new features, it’s often beneficial to experiment with a small percentage of users first—perhaps even as small as 1%. This controlled exposure allows teams to gather feedback on usability, correctness, and other factors before increasing the rollout percentage. This incremental approach can be implemented at both deployment time and runtime.

Risk mitigation

Deploying new features at scale inevitably spawns unexpected errors. Progressive delivery hedges against these risks by limiting the impact of brand new code. Minor errors can be fixed with barely a hiccup, and major catastrophes can be rolled back instantly while only affecting a small subset of users.

Improved user experience

Changing features directly impacts user experience. Progressive delivery lets you gauge user response to changes, avoiding large scale backlash. You can even do advanced feature testing, pushing different versions to different groups and seeing which implementation has the best response.

Progressive delivery with feature flags

Feature flags enable or disable features in real-time without deploying new code. It provides flexibility in managing features across different user segments, environments, or stages of development. 

Feature flags play a key role in progressive delivery by enabling gradual rollouts to specific user groups or percentages. This approach reduces risk by allowing teams to monitor performance and user feedback, making it easy to adjust or roll back changes if issues arise.

The Unleash approach to progressive delivery with feature flags

Unleash empowers teams to manage progressive delivery with precision and control, ensuring safer and faster deployments. Its flexible and robust feature flagging platform allows teams to experiment, reduce risks, and deliver better user experiences.

Key features that enable progressive delivery include:

• Kill Switches
  Unleash provides kill switches to instantly disable problematic features, minimizing downtime and impact on users. This ensures swift issue resolution without the need for redeployments. 
• Rollbacks
  Rollbacks allow teams to revert to previous feature states seamlessly, providing a safety net for unforeseen issues during rollouts. With Unleash, rollbacks can be performed instantly, reducing the risk of prolonged disruptions. 
• Strategy Constraints
  Strategy constraints in Unleash enable targeted rollouts based on attributes like user location, environment, or custom criteria. This precise control supports gradual and risk-free feature deployment.

 

Open source options for feature management

Unlike proprietary software where users are bound to the product roadmap determined by the company (and its shareholders), an open-source feature management system allows you to modify and improve the software based on your specific use cases. Our users are not bound or dependent on the limitations of our code.

Unleash open source is available as a docker container, or click-to-deploy in Heroku and Digital Ocean. Choose your preferred deployment and get started in minutes.

While there are other proprietary tools such as LaunchDarkly, we believe there are a lot of benefits to using an open-source system like ours. Ready to implement Progressive Delivery in your DevOps pipeline?  Explore how Unleash supports Progressive Delivery, or try it for free today.

 

FAQs about Progressive Delivery

What is progressive delivery and how does it work?

Progressive delivery is a software release approach that gradually introduces new capabilities to a subset of users before wider adoption. It combines progressive deployment, which rolls out new software versions to small user groups, with progressive release, which makes specific features available at runtime. This method allows teams to test changes in a live production environment, gather real-world feedback, and expand the release based on verified results. It reduces risk and ensures changes are technically sound and meet user needs effectively.

How do feature flags enable progressive delivery?

Feature flags are pivotal in progressive delivery by allowing dynamic control over features without requiring new code deployments. They enable gradual rollouts to specific user groups or percentages, decoupling deployment from feature release. This flexibility reduces risk by letting teams monitor performance and gather feedback from limited audiences. If issues arise, features can be instantly disabled or rolled back, providing a critical safety net.

What are the key benefits of adopting progressive delivery?

Adopting progressive delivery significantly reduces the risk associated with new software releases by identifying issues early within limited user segments. It accelerates feedback loops, allowing teams to iterate rapidly based on real user behavior and performance data. This approach leads to improved software quality, better user experiences, and enhanced flexibility to respond quickly to market changes. It also fosters greater collaboration between development, operations, and product teams.

How does progressive delivery differ from continuous delivery?

While continuous delivery focuses on maintaining code in a constantly deployable state, progressive delivery extends this by meticulously controlling how and to whom new features are released. Continuous delivery ensures fast and frequent deployments, but progressive delivery adds a layer of risk mitigation by enabling gradual exposure to specific user subsets. It shifts the focus from simply getting code into production to managing the user experience of new features in a controlled, iterative manner. This allows for testing in production and making data-driven decisions before a full rollout.

What deployment strategies are commonly used in progressive delivery?

Common strategies include canary releases, which deploy a new version to a small user group before a full rollout to monitor performance. Blue/green deployments involve maintaining two identical production environments and switching traffic to the new version once validated. Feature flags are also central, allowing specific functionalities to be toggled on or off for different user segments. A/B testing is another strategy that compares variations of a feature to determine which performs better based on user data.