Thomas Kosiewski
Senior Software Engineer at Coder
Frankfurt, Hesse, Germany
Summary
🤩
Rockstar🎓
Top SchoolThomas Kosiewski is a Senior Software Engineer with 12 years of experience building cloud-native, security-focused systems from Frankfurt, Germany. He has deep hands-on expertise in Kubernetes, networking and distributed systems—contributing to prominent open-source projects like vcluster and external-dns where he added Traefik support and modernized logging and dependency management. At Loft Labs he implemented secure tunneling and reimplemented parts of a Tailscale-like control plane to enable seamless cross-component networking, and earlier at Merck he engineered IAM integrations, multi-cluster HA and disaster recovery on AWS EKS. Comfortable across Go, Rust, DevOps and CI/CD, he blends backend development with infrastructure and automation work, often shipping features and infra in parallel. Colleagues value him for pragmatic refactors (context propagation, dependency updates) that reduce technical debt while enabling commercial SaaS features.
12 years of coding experience
6 years of employment as a software developer
Technischen Universität DarmstadtAbitur, Abitur at Friedrich-Dessauer-Gymnasium
English, Polish, German
Stackoverflow
144reputation
8kreached
10answers
1question
Github Skills (30)
kubernetes10
docker10
ingress10
dockers10
cicd10
vcluster10
go10
kubernetes-pods10
logging10
traefik10
devops10
scripting9
dependency-management9
dns9
helm9
Programming languages (14)
Github contributions (5)
loft-sh/vcluster
Mar 2023 - Dec 2024
vCluster - Create fully functional virtual Kubernetes clusters - Each vcluster runs inside a namespace of the underlying k8s cluster. It's cheaper than creating separate full-blown clusters and it offers better multi-tenancy and isolation than regular namespaces.
Role in this project:
Backend Developer
Backend DeveloperContributions:20 releases, 277 reviews, 251 PRs in 1 year 9 months
Contributions summary:Thomas focused on refactoring the codebase to use v2 of the klog library instead of v1, indicating a shift to a newer logging system. They updated dependencies to their latest versions, including Dependabot and Docker configurations, and introduced context passing throughout the codebase. These changes involved modifying multiple files related to server handling, helm secrets, and controllers within the `vcluster` project.
clustershelmvclusterk8scheaper
loft-sh/devpod
May 2023 - Dec 2024
Codespaces but open-source, client-only and unopinionated: Works with any IDE and lets you use any cloud, kubernetes or just localhost docker.
Role in this project:Backend & DevOps Engineer
Backend & DevOps EngineerContributions:25 reviews, 11 PRs, 5 pushes in 1 year 7 months
Contributions summary:Thomas primarily contributed to the backend and DevOps aspects of the `loft-sh/devpod` repository. Their work includes adding and configuring linters, refactoring code to handle errors and dependencies, and implementing essential features like a troubleshooting command. Furthermore, the user demonstrates knowledge of Kubernetes and Docker, with edits that involve interacting with Kubernetes resources and ensuring the correct operation of containers. The user also worked on the automation side including the creation of a script wrapper.
clouddevcontainerdevcontainersdeveloper-toolsdocker
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