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Derek Su

PROFILE

Derek Su

Derek Su engineered core storage and infrastructure features for the Longhorn project, focusing on longhorn-manager and longhorn-instance-manager repositories. He delivered robust API enhancements, migrated resource validation to Kubernetes admission webhooks, and modernized CRDs to streamline upgrade paths and ensure data integrity. Using Go and Kubernetes, Derek consolidated dependency management, improved CI/CD automation, and introduced log rotation for container stability. His work included refactoring error handling with cockroachdb/errors, enhancing observability, and implementing UUID-based instance tracking. Derek’s technical depth is evident in his approach to concurrency, configuration management, and system programming, resulting in maintainable, production-ready storage orchestration components.

Overall Statistics

Feature vs Bugs

66%Features

Repository Contributions

249Total
Bugs
43
Commits
249
Features
83
Lines of code
192,858
Activity Months12

Work History

October 2025

9 Commits • 1 Features

Oct 1, 2025

October 2025 monthly summary for developer work across longhorn-manager and longhorn-instance-manager, focusing on stability, reliability, and maintainability. Delivered concrete fixes and structural improvements to reduce downtime risk, improve error visibility, and streamline future changes. Key delivery included targeted bug fixes, dependency upgrades, and config correctness enhancements that collectively improve production readiness and developer experience.

September 2025

37 Commits • 11 Features

Sep 1, 2025

September 2025 performance summary for Longhorn repositories, focusing on reliability, observability, and data-engine readiness across manager components, with notable maintenance and security cleanups.

August 2025

52 Commits • 24 Features

Aug 1, 2025

August 2025 monthly summary focusing on delivering data-engine governance improvements, reliability enhancements, and developer tooling across Longhorn components. Major work centers on CRD/data engine settings modernization, datastore consolidation, validation enhancements, and upgrade/webhook reliability, with targeted performance and logging improvements to support scalable operations.

July 2025

11 Commits • 3 Features

Jul 1, 2025

July 2025 monthly summary: Delivered automation, stability, and observability improvements across Longhorn manager components. Key features include CI/CD workflow authentication and PR automation improvements using a Longhorn bot and GitHub App tokens (with workflow_dispatch and token substitution). Implemented Kubernetes CRD compatibility cleanup removing preserveUnknownFields and renaming V2DataEngineRebuildingMbytesPerSecond to ReplicaRebuildBandwidthLimit. Enhanced diagnostics by recording the exact scheduling failure reason in volumes' Scheduled condition. Fixed replica cleanup health logic to count only healthy and active replicas. Refactored disk metrics collection to a dedicated collector, removing the DiskMetrics field. Added log rotation in the Longhorn Instance Manager Docker image to stabilize containers and prevent disk space growth. These changes increase security, reliability, and maintainability while delivering concrete business value in faster PR cycles, safer data operations, and improved observability.

June 2025

7 Commits • 3 Features

Jun 1, 2025

June 2025 monthly summary: Delivered key architecture and reliability improvements across Longhorn manager and instance-manager, with a focus on business value, maintainability, and operational stability. Highlights include migrating core resource validation/mutation to admission webhooks for centralized validators/mutators, enhancing troubleshooting for engine images, API cleanup to align CRDs, and substantial CI/CD and build reliability improvements. Key achievements: - Migrated validation/mutation logic for EngineImage, Node, and Replica to admission webhooks, centralizing validators/mutators for consistency and maintainability. Commit: a56819105fd965b73dbc70133e1eb5814d3bea91. - Enhanced engine image troubleshooting by adding granular error reporting for binary checks in engineBinaryChecker and its usage in syncEngineImage. Commit: c65035e66994398af24fadd77c3684e253f72f11. - CRD cleanup: removed deprecated evictionRequested field from ReplicaStatus and updated Go API and client apply configurations. Commit: 16505d0d1aa1f53ead569887271f2eb168a73729. - CI workflow reliability fixes: fetch CRDs from the PR target branch to avoid compatibility issues and fix curl usage to reliably download crds.yaml with proper quoting and fail-on-error handling. Commits: 43e36b45f5b73daf4d19b90633dc15cdaed0abd8; a79573a761d58bad7a2a55e8ca76a8c24b32b07c. - Docker image build reliability: cache busting in Dockerfile to avoid stale dependencies and move libqcow build to dedicated repository (longhorn/libqcow) for centralized dependency management. Commits: fdca8414344fb37a19f688b7e8c3bf5b70dd3779; 8e15bd425cc4dadaa6dc334a3c150dc9ec1f9a54. Overall impact and accomplishments: - Increased CI stability and compatibility between PRs and target branches, reducing flaky checks and onboarding time. - Improved developer productivity through centralized validators, clearer engine image troubleshooting, and API/API client alignment. - More reliable Docker builds with centralized dependency sourcing, decreasing risk of stale dependencies and build failures. Technologies and skills demonstrated: - Kubernetes CRDs and admission webhooks, Go-based validators/mutators, and API design evolution. - CI/CD optimization, including PR-target branch synchronization and robust curl handling. - Dockerfile optimization and multi-repo dependency management (longhorn/libqcow).

May 2025

22 Commits • 7 Features

May 1, 2025

May 2025 monthly summary focusing on delivering durable business value through enhanced identity, lifecycle management, observability, and upgrade readiness across Longhorn components. The work delivered UUID-based identity for instances, safer orphan-resource handling, robust snapshot lifecycle, expanded health visibility, and targeted maintenance to modernize dependencies and APIs, strengthening reliability and future-proofing.

April 2025

9 Commits • 5 Features

Apr 1, 2025

Summary for 2025-04 focusing on longhorn-manager and longhorn-instance-manager. Delivered features and reliability improvements with a strong emphasis on business value, streamlined upgrade paths, and enhanced automation across CI/CD.

March 2025

26 Commits • 7 Features

Mar 1, 2025

February 2025-03 monthly summary for Longhorn development. Delivered targeted improvements across core manager, tests, and infra, with an emphasis on reliability, maintainability, and business value. The work emphasizes snapshot integrity, API stability, and build quality, enabling safer upgrades and faster delivery.

February 2025

18 Commits • 6 Features

Feb 1, 2025

February 2025 performance overview: Delivered major build and reliability enhancements across Longhorn components, including centralized dependency version management, SPDK engine robustness, Kubernetes client-go upgrade for CLI stability, LUKS status utilities, and CI workflow improvements. These work streams collectively improve deployment reproducibility, runtime reliability, observability, and developer productivity while reducing operational risk.

January 2025

27 Commits • 7 Features

Jan 1, 2025

January 2025 monthly summary focusing on key achievements and business value across Longhorn components. Key features delivered: - SPDK Engine Upgrade and Robustness Improvements (longhorn-instance-manager): Upgraded SPDK dependencies, vendor updates, and improved replica add/rebuild error handling, plus enhanced backup/status logging and replica deletion behavior tweaks for greater observability and reliability. - CI/CD and Dependency Management Improvements: Centralized dependency versions, updated build environments, and streamlined workflows to ensure consistent, reliable builds across platforms, including ARM64 runners and refreshed repos. - Environment checks and improved logging: Clearer visibility when environment checks are skipped and refined logs to distinguish context cancellations from other errors, aiding faster troubleshooting. - V2 Data Engine status labeling: Updated terminology from Preview to Experimental to better reflect the development stage in the UI and settings. - Kubernetes CRD generation and automation enhancements: CRD generation scripts updated, tool version bumps, and build validation improvements to automate and stabilize CRD updates. Major bugs fixed: - StorageAvailable calculation refinement for disks (longhorn-manager): Truncate only DiskTypeFilesystem (logs/files) disks, preserving accurate storage reporting for block-type disks. - BackupTargetController: Added a mutex to protect bsTimerMap to ensure thread-safety during reconciliation and cleanup, eliminating race conditions. Overall impact and accomplishments: - Significantly improved storage provisioning stability, observability, and data integrity through SPDK upgrades and safer concurrent handling. - Increased release reliability and maintainability via centralized dependency management and CI/CD workflow improvements. - Enhanced clarity and maintainability of environment checks and logs, enabling faster incident response. - Strengthened Kubernetes CRD tooling and automation, reducing manual drift and improving deployment consistency. Technologies/skills demonstrated: - SPDK, Go, and systems-level robustness; concurrency controls (mutexes); enhanced logging and observability techniques; CI/CD automation and dependency version management; Kubernetes CRD tooling and automation; cross-repo coordination and release hygiene.

December 2024

30 Commits • 8 Features

Dec 1, 2024

December 2024 delivered a focused set of reliability, data integrity, and observability enhancements across Longhorn core components, translating into tangible business value for production workloads. Key features include live engine upgrade support, snapshot integrity improvements, SPDK engine robustness, startup reliability improvements, and comprehensive monitoring enhancements. Additional IO tuning and configuration externalization further reduce operational risk and manual intervention, while a strengthened test and observability baseline supports faster iteration and safer releases.

October 2024

1 Commits • 1 Features

Oct 1, 2024

Month: 2024-10 — Focused on stabilizing the longhorn-instance-manager stack through targeted dependency modernization. Delivered a high-impact change: nvme-cli updated to version 2.10.2 in the Dockerfile to improve stability and compatibility across environments. This aligns with the maintenance plan for NVMe tooling and reduces deployment risk for users relying on the instance manager. No major bugs fixed this month; the effort prioritized tooling resilience and release hygiene. The change is traced to repository longhorn/longhorn-instance-manager with commit ceaabbacce2425f7860bc67117a21d4f572893a4.

Activity

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Quality Metrics

Correctness89.8%
Maintainability89.8%
Architecture87.0%
Performance83.0%
AI Usage20.2%

Skills & Technologies

Programming Languages

BashDockerfileGoJSONMakefileProtocol BuffersPythonRobot FrameworkRobotFrameworkRoff

Technical Skills

API DesignAPI DevelopmentAPI DocumentationAPI IntegrationAPI InteractionAPI ManagementAPI VersioningAPI developmentAdmission WebhooksBackend DevelopmentBot IntegrationBug FixBuild AutomationBuild EngineeringBuild Process

Repositories Contributed To

3 repos

Overview of all repositories you've contributed to across your timeline

longhorn/longhorn-manager

Dec 2024 Oct 2025
11 Months active

Languages Used

GoShellBashMakefileYAMLbashgoshell

Technical Skills

Backend DevelopmentCloud InfrastructureCloud NativeConfiguration ManagementError HandlingGo

longhorn/longhorn-instance-manager

Oct 2024 Oct 2025
12 Months active

Languages Used

DockerfileGoProtocol BuffersShellYAMLMakefilebash

Technical Skills

Build ProcessDependency ManagementAPI DevelopmentBackend DevelopmentConcurrency ControlGo

longhorn/longhorn-tests

Dec 2024 Sep 2025
5 Months active

Languages Used

PythonRobot FrameworkJSONRobotFramework

Technical Skills

Integration TestingPython ScriptingPythonRegression TestingTest AutomationEnd-to-End Testing

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