Intro

Addressing technical debt is a challenging task. As your codebase expands and becomes more complex, refining and improving the system becomes increasingly difficult. The Strangler Pattern presents a powerful solution for gradually replacing portions of a monolithic system, mitigating risks associated with complete rewrites. The pattern's primary advantage lies in its emphasis on decommissioning features incrementally, significantly reducing the dangers of large-scale rewrites.

While major rewrites may be enticing due to the opportunity for a fresh start and designing an ideal architecture, they often carry significant risks, such as budget overruns, delays, and the potential for introducing new defects. Committing to a significant rewrite also entails constantly competing with the previous version as you strive to keep up with new features being added to the legacy system. Eventually, the initial goal behind the new system may be lost, and you could find yourself repeating past mistakes, leading you back to the same predicament.

The Strangler Pattern is a software architecture technique used to gradually replace legacy or inefficient parts of a system. Inspired by the strangler fig tree, which grows around an existing tree and slowly replaces it, the pattern involves creating a new system with enhanced architecture and progressively migrating functionality from the old system to the new one. This is achieved by implementing new features in the new system and leaving the old system in place to handle existing functionality. Over time, as more features are transferred to the new system, the old system becomes less critical until it can be fully decommissioned.

By employing the Strangler Pattern, you can systematically decommission features and replace them with new components in a controlled manner. This not only helps you manage risk but also enables you to maintain a high level of quality and stability throughout the transition.

In this article, we'll outline a simple 6-step process that will help you decommission features in a controlled, incremental manner while closely monitoring risks and quality.

Step 1: Identify the Problem Areas with Data-Driven Insights

First, pinpoint the problematic parts of your codebase causing issues or slowing you down. Look for bottlenecks, areas with high technical debt, or sections with numerous defects. Utilize metrics, feedback, and team input to locate these troublesome areas. For a quicker, data-backed approach, employ the "High-Usage and High-Complexity Analysis."

"High-Usage and High-Complexity Analysis" enables you to concentrate on the most critical parts of your codebase. Begin by examining your GitHub repository. Utilize built-in commands to identify high-usage areas from the past 12 months. Next, analyze code complexity using tools like SonarQube or Snyk. Armed with these data points, focus on the upper right quadrant, where high-usage and high-complexity areas reside. These are the sections of the codebase that require the most attention.

Employing this data-driven method, you'll quickly pinpoint the messiest areas of your codebase. Equipped with this information, you can initiate the cleanup process and implement improvements where they matter most.

Step 2: Collaboratively Develop Solutions

After identifying the problematic areas, it's time to address them. Research and consider various ideas, taking into account factors like complexity, cost, time to implement, and impact. Collaborate with your team to gain a better understanding of the problem. Together, you'll discover the ideal solution. Here are some tips:

1. Organize a Team Huddle: Assemble your team for a brainstorming session. Encourage open discussions and creative thinking. All ideas are welcome.
2. Divide the Problem: Break the problem into smaller, manageable pieces. This helps your team concentrate and develop targeted solutions.
3. Prioritize Your Solutions: Evaluate and prioritize ideas based on feasibility, impact, and cost. Aim for solutions that strike a balance between benefits and risks.
4. Test the Waters: For the top choice, create a small-scale prototype or demo. This checks if the approach works and identifies issues before a full commitment.
5. Refine Together: Share the prototype with your team. Gather feedback and fine-tune the solution. Collaboration ensures the best fit for your codebase.

At this stage, draft a rough plan with timelines and break the project into digestible parts. This will be helpful in the next step when you need to gain support from a wider range of stakeholders.

Step 3: Secure Stakeholder Buy-In

Now, it's time to share your plan with stakeholders, including team members, managers, and other key individuals. Explain the benefits, timeline, and resources needed. Gaining their support will make the transition smoother.

It's crucial to demonstrate the impact of not addressing the problem on the business, customers, and the engineering team. Use the data from Step 1 to build a strong case. Explain how gradual, incremental changes will help manage risks and encourage learning.

Here's how to get everyone on board:

1. Showcase the Impact: Emphasize the consequences of not taking action. Discuss how it affects the business, customers, and your team. Use data to support your argument.
2. Highlight Benefits: Share the positive outcomes of your plan. Explain how it will improve the system, reduce technical debt, and increase productivity.
3. Present the Timeline: Provide a clear timeline with milestones. Show stakeholders the roadmap for the project, including the steps you'll take to achieve your goals.
4. Discuss Resources: Outline the resources needed, such as team members, tools, and budget. Be transparent about the investment required for success.
5. Champion Gradual Change: Stress the importance of incremental improvements. Explain how this approach helps manage risks and allows for learning from experience.

By presenting a well-prepared plan and emphasizing the benefits of gradual, incremental changes, you'll rally the support you need for a smoother transition.

Step 4: Implement Changes Gradually

With support secured, begin addressing the problematic areas. Add new components or improvements while ensuring the system continues to run smoothly. Test everything thoroughly and use automated tools and continuous integration for better quality. Follow industry best practices and patterns, like branch-by-abstraction and Event-Interception, for code architecture. Use feature toggles for canary releases. Monitoring is essential!

Here's how to implement changes slowly and carefully:

1. Adhere to Best Practices: Use proven patterns and practices when updating code architecture. This ensures a more stable and maintainable system.
2. Embrace Automation: Implement automated tools and continuous integration. They improve code quality and help catch issues early.
3. Monitor Progress: Keep a close eye on your system and user impact. Implement observability from the start to measure changes effectively.
4. Use Feature Toggles: Enable canary releases with feature toggles. This allows you to test new components in a controlled manner.
5. Stay Patient: It might feel strange to write more code without removing any, but this approach is all about managing risks and minimizing system impact. You're avoiding major changes all at once.

By following these guidelines, you'll gradually improve your codebase while keeping risks and impact on the existing system under control.

Step 5: Monitor the Changes

As you replace old components with new ones, stay vigilant. Monitor the system's performance, error rates, and other relevant metrics. This helps you catch issues and ensures the new components work as intended.

Use tools like DataDog or New Relic for observability, monitoring, and alerting. The more code you replace, the more crucial it is to track the data. With feature toggles in place, it's just a flip of a switch to revert to the previous functionality if any major issues arise.

Here are some tips for effective monitoring:

1. Implement Observability: Use tools like DataDog or New Relic to gain insight into your system's performance and health. Set up monitoring and alerting to stay informed.
2. Monitor Key Metrics: Keep an eye on important metrics, like performance, error rates, and user satisfaction. These indicators help you identify problems and ensure smooth operation.
3. Set Alerts: Configure alerts to notify you of any anomalies or issues. This enables you to react quickly and minimize the impact on users.
4. Review Regularly: Regularly review the collected data and system performance. Use this information to fine-tune your approach and improve the transition process.
5. Stay Ready to Revert: With feature toggles, be prepared to revert to the previous functionality if needed. This safety net helps you manage risks and maintain system stability.

By closely monitoring your system as you introduce new components, you'll maintain a high-quality user experience and quickly address any issues that arise.

Step 6: Decommission Old Components

Finally, it's time to remove the old components. Be cautious with dependencies and ensure the new parts are fully functional. Continue monitoring performance and other metrics, as you did in Step 5. This guarantees a smooth transition and an excellent user experience.

It's crucial not to skip this step. You may be tempted, but if you've planned well, you should have enough time and buy-in to tackle this stage. With all previous steps completed, removing the legacy code should be straightforward.

Here's how to decommission old components:

1. Verify Dependencies: Be thorough in checking dependencies to ensure a seamless removal of old components.
2. Confirm Functionality: Make sure the new components are fully functional and perform as expected.
3. Remove Feature Toggles: With only one version of the code in production, there's no need for feature toggles. Remove them to simplify your codebase.
4. Double-Check Data: If data migration was part of the project, verify the data is accurate and complete. Address any anomalies promptly.
5. Consult the Team: Check with the wider team to ensure everything is in order and no issues remain.

By carefully following these steps, you'll successfully decommission legacy components, maintain a smooth transition, and provide a top-notch user experience.

Closing Thoughts

In conclusion, the Strangler Pattern offers a powerful and effective approach to managing and upgrading your codebase. By tackling challenges incrementally and focusing on collaboration, risk management, and quality, you can transform your system without the perils of full-scale rewrites.

Remember, the journey to a cleaner, more maintainable codebase is not a sprint but a marathon. It requires patience, determination, and the support of your team and stakeholders. Embrace the process, learn from each step, and celebrate your progress along the way.

As you embark on this transformative journey, you'll not only improve your system's performance and stability but also create an environment that fosters innovation, adaptability, and growth. Combined with the Strangler Pattern, this mindset will empower your team to overcome technical debt, enhance user experience, and build a resilient foundation for your startup's future success.

So go forth, face the challenge, and conquer your codebase—one step at a time.

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Need help tackling your technical debt? Get in touch at sales@dlabs.io.

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