Denis Levenko_

stack Ruby 3.1 (and 2.4–2.6 legacy), Rails 4.2 → 7.1, Go, Python, Hotwire, PostgreSQL, Redis, Docker / Compose / Swarm, GitLab CI/CD, Ansible, Nginx / Caddy / Traefik, Consul

• Migrated two thirds of production services to Ruby 3, in a codebase that still spans Rails 4.2 through 7.1.
• Set up GitLab CI/CD across every repository — build, tests and linter on each change — replacing ad-hoc manual checks.
• Write and optimise Ansible roles and playbooks, and containerise services with Docker, Docker Compose and Swarm.
• Built several internal products in Go.
• Use Claude Code, Codex and Gemini day to day to speed up development, review code and build LLM-based tools, checking the generated code and understanding how it works.
• Documented every internal service — the reference the team now onboards and debugs from.
• Mentor an intern on Go, Ruby, Python and CI/CD tasks through code reviews and debugging sessions.
• Built an image comparison prototype (Go, Python, Milvus) that grew into a standalone project.

• Built UI and API test automation from scratch (Ruby — Selenium — RSpec — Page Object — Allure) and trained the team to write it.
• Wrote 80% of the project documentation and kept testing processes improving through heavy staff turnover.
• Onboarded 10+ new employees into the test process as their mentor; owned testing strategy across web and mobile.