Maintainable

Software maintenance is often framed as a technical problem. Refactoring code, fixing bugs, or upgrading dependencies. In this conversation, Robby Russell talks with Rein Henrichs about a different lens, one centered on understanding.

Rein is a Principal Software Engineer at Procore, where he works within a large, long-lived system used across the construction industry. Rather than focusing on tooling, Rein emphasizes that well-maintained software is software that makes sense to the people maintaining it.

To explain this, Rein introduces the idea of the line of representation, drawing on the work of Richard Cook. Engineers do not interact directly with systems. They rely on representations such as logs, dashboards, and code. These are approximations, not reality, echoing ideas from Plato’s Allegory of the Cave.

When those representations break down, teams lose shared understanding, what Rein describes as “common ground.” This often shows up as weak signals. Subtle indicators that something is not quite right. They are easy to ignore, but over time they lead to confusion and slower decision-making.

Incidents make this especially visible. Rein explains how teams build alignment under pressure, highlighting that the role of an incident commander is coordination, not control. Clear communication matters as much as technical correctness.

The conversation also explores how large systems behave in practice. They rarely fail completely. Instead, they degrade in multiple ways at once. While SLOs can help teams respond to customer-facing issues, they do not capture internal clarity or alignment.

Rein references W. Edwards Deming to highlight a common trap. Not everything that matters can be measured. High-performing teams often rely on judgment, experience, and shared context.

Toward the end, Rein connects these ideas to The Field Guide to Understanding Human Error by Sidney Dekker, challenging the idea that incidents are simply caused by mistakes. Instead, they emerge from the same behaviors that usually lead to success, just under different conditions.

For teams working in complex systems, the takeaway is straightforward. Maintaining software depends on maintaining understanding.

Links & Resources

Procore

Rein Henrichs on LinkedIn

Concepts & References

How Complex Systems Fail – Richard Cook

The Field Guide to Understanding Human Error – Sidney Dekker

W. Edwards Deming

Gerald Weinberg – Secrets of Consulting

Referenced in this Conversation

Kent Beck: You’re Ignoring Optionality and Paying for It

Charity Majors: Deploys Are Just the Beginning

Heidi Helfand: The Art and Wisdom of Changing Teams

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It offers six powerful features with one simple interface, providing developers with real-time insights into the performance and health of web applications.

Keep your coding cool and error-free, one line at a time! 

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Software doesn’t become hard to maintain only because the code is messy. It often becomes hard to maintain because the reasoning behind it disappears.

In this episode of Maintainable, Robby Russell talks with Russ Olsen about trade-offs, legacy systems, and why maintainability depends on context more than dogma. Russ brings decades of experience across very different kinds of systems, each with its own definition of what “maintainable” actually means.

A central theme is that software must be understandable to the people maintaining it. Teams tend to document implementation details well, but often fail to capture system-level intent and the trade-offs behind major decisions. Russ makes the case for preserving that thinking, including the alternatives that were rejected, so future maintainers don’t have to rediscover it the hard way.

The conversation also touches on Russ’s book Eloquent Ruby, Second Edition. Rather than teaching syntax, the book focuses on how Ruby is actually used in practice and why common patterns exist. That leads into a discussion about where elegance improves maintainability, and where it turns into unnecessary cleverness.

From there, the episode shifts into the realities of working in legacy systems. Russ explains how teams develop pessimism over time, often accepting flawed assumptions about how their systems behave. In some cases, major issues turn out to be far simpler than expected. The challenge is that teams stop looking.

Robby and Russ also discuss the value of fresh perspective. New engineers or outside contributors can surface assumptions that longtime maintainers overlook. Russ suggests finding “pinch points” in a system as a practical way to understand behavior without needing to fully untangle everything at once.

Later, the conversation explores developer quality of life. Long build and deploy cycles create daily friction that teams often underestimate. These slow feedback loops quietly degrade productivity and morale over time.

The episode also tackles rewrites. Russ warns that teams frequently underestimate how much knowledge is embedded in existing systems. Code that looks questionable may reflect constraints no one documented. In practice, most successful rewrites happen incrementally, not all at once.

The conversation wraps with a reminder that software development is fundamentally a social process. Russ argues that engineers undervalue storytelling, even though it’s one of the most effective ways to connect technical work to real human outcomes.

Episode Highlights

[00:00:40] Defining maintainability: Why context matters more than a universal standard

[00:02:01] Beyond code comments: Documenting system intent and trade-offs

[00:08:14] Who Eloquent Ruby is for: Understanding how Ruby is used in practice

[00:16:21] Elegance vs. cleverness: Where maintainability starts to erode

[00:23:18] Legacy pessimism: Why teams stop questioning assumptions

[00:29:25] Pinch points: A practical way to understand complex systems

[00:32:05] Developer experience: The hidden cost of slow feedback loops

[00:38:26] Rewrites: Why they fail and what teams overlook

[00:44:00] Storytelling: Connecting technical work to real-world impact

Resources Mentioned

Russ Olsen on LinkedIn

Eloquent Ruby, Second Edition

Getting Clojure

Zen and the Art of Motorcycle Maintenance

A History of Western Philosophy

Thanks to Our Sponsor!

Turn hours of debugging into just minutes! AppSignal is a performance monitoring and error-tracking tool designed for Ruby, Elixir, Python, Node.js, Javascript, and other frameworks.

It offers six powerful features with one simple interface, providing developers with real-time insights into the performance and health of web applications.

Keep your coding cool and error-free, one line at a time! 

Use the code maintainable to get a 10% discount for your first year. Check them out!

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Long-lived software systems rarely stay tidy. Over time they accumulate decisions, workarounds, and layers of history that can make even simple changes feel risky. For engineers responsible for maintaining those systems, the challenge often becomes less about writing new code and more about understanding what already exists.

In this episode of Maintainable, Robby Russell speaks with Joel Oliveira, Engineering Manager at ezCater, about what helps software remain understandable and adaptable as it evolves.

Joel starts with a principle that often gets overlooked: predictability. When patterns are consistent and code is organized in familiar ways, engineers can navigate a codebase with confidence. Frameworks like Ruby on Rails reinforce this by encouraging shared conventions, making it easier for developers to orient themselves when working in a new application.

The conversation also explores how common metrics can be misleading. Test coverage is often treated as a proxy for quality, but Joel explains that it can create a false sense of confidence. Instead, he values testing most as a thinking tool. Practices like test-driven development can help engineers clarify interfaces and better understand the problem before committing to an implementation.

Joel also shares a story from ezCater about replacing an aging image-cropping service that had become difficult to maintain and required frequent restarts due to a memory leak. Rather than patch the system again, the team introduced ImageProxy, an open source image processing tool created by Evil Martians.

Because the image URLs flowed through a single object in their GraphQL layer, the team could introduce an adapter and gradually route traffic to the new service using feature flags. This allowed them to migrate safely and incrementally instead of relying on a risky “big bang” change.

Robby and Joel also discuss how engineers’ perspectives shift over time. Early in a career it is easy to look at legacy code and label it as bad. Joel now sees older systems as layers of decisions shaped by real constraints. Approaching them with empathy makes it easier to improve them thoughtfully.

The episode closes with advice for engineers maintaining complex systems: frame problems as opportunities. By documenting impact and proposing incremental improvements, teams can steadily move their software toward a healthier future.

Maintainable software rarely comes from one heroic refactor. More often, it’s the result of many small improvements made by teams who understand their systems and care about how they evolve.

Episode Highlights

00:02:18 – Predictability as a Maintainability Feature

Joel explains why predictable patterns and conventions make large codebases easier to navigate.

00:07:41 – When Test Coverage Misleads

Why high coverage can give a false sense of quality.

00:12:05 – Consulting vs. Product Engineering

How switching environments shaped Joel’s approach to code.

00:16:32 – Replacing a Legacy Image Service

ezCater’s migration away from a failing Node-based image service.

00:21:14 – Migrating with Adapters and Feature Flags

How the team gradually moved traffic to ImageProxy.

00:26:03 – Developing Empathy for Legacy Code

Why older systems deserve understanding, not blame.

00:30:47 – The Shift to Engineering Management

Joel reflects on moving from IC work to leading teams.

00:34:52 – Advice for Improving Complex Systems

Small, consistent improvements matter more than big rewrites.

Thanks to Our Sponsor!

Turn hours of debugging into just minutes! AppSignal is a performance monitoring and error-tracking tool designed for Ruby, Elixir, Python, Node.js, Javascript, and other frameworks.

It offers six powerful features with one simple interface, providing developers with real-time insights into the performance and health of web applications.

Keep your coding cool and error-free, one line at a time! 

Use the code maintainable to get a 10% discount for your first year. Check them out!

Links / References

Joel Oliveira — LinkedIn

Joel Oliveira — Website

Joel Oliveira — Mastodon (@jayroh)

ezCater

ImageProxy

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Maintaining software over time rarely fails because of one bad decision. It fails because teams stop getting clear signals… and start guessing.
In this episode, Robby talks with Lucas Roesler, Managing Partner and CTO at Contiamo. Lucas joins from Berlin to unpack what maintainability looks like in practice when you are dealing with real constraints… limited context, missing documentation, and systems that resist understanding.
A big through-line is feedback. Lucas argues that long-lived systems become easier to change when they provide fast, trustworthy signals about what they are doing. That can look like tests that validate assumptions, tooling that makes runtime behavior visible, and a habit of designing for observability instead of treating it as a bolt-on.
The conversation also gets concrete. Lucas shares a modernization effort built on a decade-old tangle of database logic… views, triggers, stored procedures, and materializations… created by a single engineer who was no longer around. With little documentation to lean on, the team had to build their own approach to “reading” the system and mapping dependencies before they could safely change anything.
If you maintain software that has outlived its original authors, this is a grounded look at what helps teams move from uncertainty to confidence… without heroics, and without rewriting for sport.
Episode Highlights
[00:00:46] What well-maintained software has in common: Robby asks Lucas what traits show up in systems that hold together over time.
[00:03:25] Readability at runtime: Lucas connects maintainability to observability and understanding what a system actually did.
[00:16:08] Writing the system down as code: Infrastructure, CI/CD, and processes as code to reduce guesswork and improve reproducibility.
[00:17:42] How client engagements work in practice: How Lucas’ team collaborates with internal engineering teams and hands work off.
[00:25:21] The “rat’s nest” modernization story: Untangling a legacy data system with years of database logic and missing context.
[00:29:40] Making data work testable: Why testability matters even when the “code” is SQL and pipelines.
[00:34:59] Pivot back to feedback loops: Robby steers into why logs, metrics, and tracing shape better decision-making.
[00:35:20] Why teams avoid metrics and tracing: The organizational friction of adding “one more component.”
[00:42:59] Local observability with Grafana: Using visual feedback to spot waterfalls, sequential work, and hidden coupling.
[00:50:00] Non-technical book recommendations: What Lucas reads and recommends outside of software.
Links & References
Guest and Company
Lucas Roesler: https://lucasroesler.com/
Contiamo: https://contiamo.com/
Social
Mastodon: https://floss.social/@theaxer
Bluesky: https://bsky.app/profile/theaxer.bsky.social
Books Mentioned
The Wheel of Time (Robert Jordan): https://en.wikipedia.org/wiki/The_Wheel_of_Time
Accelerando (Charles Stross): https://en.wikipedia.org/wiki/Accelerando
Charles Stross: https://en.wikipedia.org/wiki/Charles_Stross
Thanks to Our Sponsor!
Turn hours of debugging into just minutes! AppSignal is a performance monitoring and error-tracking tool designed for Ruby, Elixir, Python, Node.js, Javascript, and other frameworks.
It offers six powerful features with one simple interface, providing developers with real-time insights into the performance and health of web applications.
Keep your coding cool and error-free, one line at a time! 
Use the code maintainable to get a 10% discount for your first year. Check them out!

Subscribe to Maintainable on:
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Or search "Maintainable" wherever you stream your podcasts.
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Rewrites are seductive. Clean slates promise clarity, speed, and “doing it right this time.” In practice, they’re often late, over budget, and quietly demoralizing.
In this episode of Maintainable, Robby sits down with Brittany Ellich, a Senior Software Engineer at GitHub, to talk about a different path. One rooted in stewardship, readability, and resisting the urge to start over.
Brittany’s career began with a long string of rebuild projects. Over time, she noticed a pattern. The estimates were wrong. Feature development stalled. Teams burned energy reaching parity with systems they’d already had. That experience pushed her toward a strong belief: if software is in production and serving users, it’s usually worth maintaining.
[00:00:57] What well-maintained software actually looks like
For Brittany, readability is the first signal. If code can’t be understood, it can’t be changed safely. Maintenance begins with making systems approachable for the next person.
[00:01:42] Rethinking technical debt
She explains how her understanding of technical debt has evolved. Rather than a fixed category of work, it’s often anything that doesn’t map directly to new features. Bugs, reliability issues, and long-term risks frequently get lumped together, making prioritization harder than it needs to be.
[00:05:49] Why AI changes the maintenance equation
Brittany describes how coding agents have made it easier to tackle small, previously ignored maintenance tasks. Instead of waiting for debt to accumulate into massive projects, teams can chip away incrementally. (Related: GitHub Copilot and the Copilot coding agent workflow she’s explored.)
[00:07:16] Context from GitHub’s billing systems
Working on metered billing at GitHub means correctness and reliability matter more than flash. Billing should be boring. When it’s not, customers notice quickly.
[00:11:43] Navigating a multi-era codebase
GitHub’s original Rails codebase is still in active use. Brittany relies heavily on Git blame and old pull requests to understand why decisions were made, treating them as a form of living documentation.
[00:25:27] Treating coding agents like teammates
Rather than delegating massive changes, Brittany assigns agents small, well-scoped tasks. She approaches them the same way she would a new engineer: clear instructions, limited scope, and careful review.
[00:36:00] Structuring the day to avoid cognitive overload
She breaks agent interaction into focused windows, checking in a few times a day instead of constantly monitoring progress. This keeps deep work intact while still moving maintenance forward.
[00:40:24] Low-risk ways to experiment
Improving test coverage and generating repository instructions are safe entry points. These changes add value without risking production behavior.
[00:54:10] Navigating team resistance and ethics
Brittany acknowledges skepticism around AI and encourages teams to start with existing backlog problems rather than selling AI as a feature factory.
[00:57:57] Books, habits, and staying balanced
Outside of software, Brittany recommends Atomic Habits by James Clear, sharing how small routines help her stay focused.
The takeaway is clear. AI doesn’t replace engineering judgment. Used thoughtfully, it can support the unglamorous work that keeps software alive.
Good software doesn’t need a rewrite.
It needs caretakers.
References Mentioned
GitHub – Brittany’s current role and the primary environment discussed
GitHub Universe – Where Brittany presented her coding agent workflow
Atomic Habits by James Clear – Brittany’s recommended book outside of tech
Overcommitted - Podcast Brittany co-hosts
The Balanced Engineer Newsletter – Brittany’s monthly newsletter on engineering, leadership, and balance
Brittany Ellich’s website – Central hub for her writing and links
GitHub Copilot – The AI tooling discussed throughout the episode
How the GitHub billing team uses the coding agent in GitHub Copilot to continuously burn down technical debt – GitHub blog post referenced
Thanks to Our Sponsor!
Turn hours of debugging into just minutes! AppSignal is a performance monitoring and error-tracking tool designed for Ruby, Elixir, Python, Node.js, Javascript, and other frameworks.
It offers six powerful features with one simple interface, providing developers with real-time insights into the performance and health of web applications.
Keep your coding cool and error-free, one line at a time! 
Use the code maintainable to get a 10% discount for your first year. Check them out!

Subscribe to Maintainable on:
Apple Podcasts
Spotify
Or search "Maintainable" wherever you stream your podcasts.
Keep up to date with the Maintainable Podcast by joining the newsletter.