Bohdan Katrenko

Working on a high-load AdTech project, designing scalable and reliable solutions using GCP, Kubernetes, and Go. As a member of the company’s architecture board, I have contributed to the design and development of core components across the project and infrastructure. Beyond development, I introduced advanced monitoring and distributed tracing, CI-based linting, security monitoring, end-to-end testing, an On-Call process, and a stress testing framework to enhance system reliability and team efficiency. Tech stack: - Go (Golang) - Google Cloud Platform (GCP) - Kubernetes (k8s) - PostgreSQL / BigQuery - GitHub Actions & ArgoCD - Pub/Sub - Temporal

Designed and led the development of a highly scalable, reliable, and extensible multi-tenant full-text search and recommendation platform powering eCommerce experiences across multiple markets. Architected a microservice-based system that serves as the core of the company’s search and personalization engine, enabling fast, relevant, and data-driven product discovery. Collaborated cross-functionally with data, product, and infrastructure teams to deliver high-performance, fault-tolerant services with automated scaling and monitoring. - Go (primary) - Python / Bash - AWS (EC2, Cognito, S3, IAM, Lambda, RDS, EKS, ElastiCache) - - Kubernetes / Docker - Kafka / Zookeeper - Elasticsearch / PostgreSQL / Redis - Spark / Airflow - REST | gRPC - Prometheus / Grafana - CircleCI | GitHub Actions

Worked on creating a real-time system for providing a few types of info for users. App based on principles of high-availability, non-blocking parallelism (with actors model) and works with processing about 8-9k request p/sec. Technologies stack: - Golang as the main programming language for building microservice architecture. Working with gRPC/gRPC-gateway for building stateless (as it possible, because of state should be stored locally) distributed system and use: - Clickhouse DB for store analytics data, raw service provider's data. - PostgreSQL for persistent store business-logic critical data - Kafka/Zookeeper as a message broker for connection between services and disaster recovery - App deployment building on Docker stack - Prometheus/Grafana used for monitoring and checking performance.

Working on a project that provides some kind of CRUD operations for cloud-stored files. Stack: - OS drivers for mac/windows for building virtual file system and mount cloud device as volume/hard disk - REST services for connect with frontend/desktop application, provide analytics data, sync/CRUD files - App worked on some level multithreading for async file io operations. Used SQLite/BoltDB/AWS S3 like a database. AWS S3 and AWS IoT used like cloud based system for push notifications and variant of storage for some data Other things that I'm working on in the project: - OSX FUSE - Syncthing

Make REST API service and website that provide a secure and flexible view/CRUD operations on specific user's info for one of US law agency. Working with: - Golang 1.8 packages and Gorilla toolkit for building REST API, routing (gorilla toolkit has a really awesome router), io operations - HTTP/io (Pipe, WriteAt, multi-writers, etc) std package for build base application function, filling templates, implementing main application logic - PostgreSQL and AWS S3 was using as main storages for user's files and application information - we actively used views, triggers and made database audit for storing changes in the database - Cronofy api - UI/UX - JQuery / HTML / CSS / golang-templates - in this case I implemented both backend and frontend for pagination

Made Android app and website for football info - https://www.footboom.com Worked with: Standard tools/libs for Android development: - Base android framework for build application - with Activity, Fragments and built-in tools for providing async operations like AsyncTask, Service, etc. - firebase messaging for providing reliable push-notifications - SQLite as local storage for some application info (like subscriptions for some news topics). It's not like backend behavior with the database, but I had some practice in SQL. - Material design view was used as a base on UI implementation - Some base video streaming things inside WebView for the ability to view videos In this project, I had good experience with client's REST API side, multithreading with limited resources and the client's side authentication with OAuth and social networks API

Created app for a carrier (something like Uber), with ability to navigation, geolocation, tracking, cloud messaging, file management, etc. Had experience with: - Jenkins, CI for building and delivery application in Google's Play Market and for QA engineers. So, It experienced with how Jenkins works, base UI features, CI/CD workflow - Google Services, Firebase for providing push notifications, analytics and crash reports for improving user experience - Android native GPS navigation toolkit and reliable background services were one of the main features - so, I had a great practice in part of Android SDK and security programming. Because clients should always have some info about where his cargo actually located. - Cloud messaging, push-notifications for near-real-time information for customers - was used google cloud messaging and firebase as service provider - worked with UI/UX - so, I had a base knowledge of how interface should be built according to Material Design google guides Some std Android things: - Dagger 2 for dependency injection - Retrofit for providing REST API into Java application

Worked with video streaming and publishing. In this context, I worked on the implementation of RTSP/RTMP streaming for android application - so, we'd worked with CameraAPI, and was improved few open source streaming engines for Android: Have experience with: - HTTP/HTTPS - base for many kinds of video streaming protocols, so, this is was my first commercial practice with networking - RTMP and RTSP network protocols for real-time publishing/streaming video on Android device - Camera API, MediaPlayer was part of std Android framework and was used for implementation - UI/UX, material design work with designer guys for making a user-friendly app