CV

Łukasz Jan Niemier

Personal information

Email: ~@hauleth.dev

Website: https://hauleth.dev

Twitter: @hauleth

Education

  • Poznań University of Technology: Computer Science - no degree - 2012-2015
    • Secretary of AKAI - Students' Association of Web Developers

Experience

  • Hauleth.dev - Consultant - 2021+
    • DockYard/Karambit.ai - 2025
      • Architectural analysis of Karambit product
      • Prepared security analysis with detailed report with fixes
    • Eiger - 2022-2023
      • Forte.io
        • Implemented Interledger protocol for cross-chain transactions
      • Aleo Blockchain
        • Implemented GraphQL API for the on-chain data
        • Created syntax colouring library for Aleo assembly-like language for smart contracts
    • Erlang Solutions/Kloeckner GmbH - 2021 - Consultant for Elixir, Ruby, and SQL (PostgreSQL)
      • Optimised DB query performance by providing PostgreSQL structure analysis and improving indices usage
    • Remote Inc. - Senior Backend Engineer - 2020-2021
      • Architectural analysis of existing codebase
    • Kobil GmbH - Erlang/Elixir Developer - 2019-2020
      • Maintained MongoDB driver for Elixir
      • Implemented transactions for MongoDB driver in Elixir
  • Supabase - 2023-2025
    • Logflare - logs aggregation service:
      • Implemented on-the-fly decompression of incoming data that improved ingestion possibilities and reduced transfer usage (created library plug_caisson for that purpose)
      • Implemented DataDog-compatible ingestion endpoint for seamless transition from DataDog provider to Logflare
      • Improved BigQuery pipeline workflow to reduce congestion on database connections
      • Added support for AWS Cloud Events metadata extraction
      • Improved CI usage by splitting different actions to separate steps ran in parallel
      • Replaced dynamic generation of connection modules for PostgreSQL storage system with Ecto's dynamic repositories to avoid atom exhaustion
    • Supavisor - a cloud-native, multi-tenant Postgres connection pooler
      • Deployment management
      • Optimised metrics gathering system that resulted in an order of magnitude performance boost
      • Updated used OTP and Elixir versions from OTP 24 to OTP 27 and Elixir from 1.14 to 1.18
      • Reduced usage of mocking in tests to improve tests performance and volatility, resulting in reduced CI usage and improved developer experience
      • Implemented e2e tests against existing Node.js PostgreSQL clients to improve production issues
      • Implemented multi-region deployment system to provide blue/green deployments
      • Improved system observability features by making it more resilient and performant
      • Replaced usage of ct_slave with newer peer module in OTP
  • AppUnite - Full-stack Developer/DevOps - 2016-2019:
    • JaFolders/AlleFolders
      • 2x performance improvement by optimising PostgreSQL usage
      • Reduced geo-queries using PostGIS thanks to better indices and materialised views usage
      • Implemented UI and brochure viewer in Vue and SVG
    • OneMedical/Helium Health
      • Architectural redesign of application from Rails/MongoDB to Phoenix/PostgreSQL
      • Prepared hybrid deployment with on-premise/in-cloud system
      • Migrated of the existing deployments from MongoDB to PostgreSQL
  • Nukomeet - Full-stack Developer - 2015-2016
  • Prograils - Junior Developer - 2013

Organisations

  • Erlang Ecosystem Foundation - member of the Observability WG
  • OpenTelemetry Project - member of the Erlang WG

Other fields

  • Volunteer:
    • Pyrkon Fan Convention
      • Helper - 2011, 2012, 2013, 2014, 2016
      • Organizer - 2015
    • UEFA Championship 2012 - Poland-Ukraine
      • ICT Accreditation support
  • Times Person of the Year - 2006

Languages

  • Polish - mother tongue
  • English - fluent

Showcase

Notable contributions

  • Elixir language:
    • Logger reimplementation on top of Erlang's logger module
    • mix test --cover CLI output
    • Support for NO_COLOR environment variable
    • is_struct/1
    • Fixing module inspection on case-insensitive file systems
    • Support for parsing extra arguments via mix eval and eval command in release
  • Erlang OTP:
    • Support for custom devices in logger_std_h
    • Fixing socket module to support broader set of protocols (for example ICMP)
    • Support for global metadata in logger
    • Support for reconfiguration of logger (needed for better Mix and Rebar3 integration)
    • Several fixes to logger and socket modules
    • Add support for τ constant in math
  • Git:
    • Add support for Elixir in diff
  • Ecto:
    • Support aggregations over *
    • Better error on duplicated schema block
  • Elixir MongoDB driver
    • Support for transactions

Notable projects

Languages and Frameworks

  • Elixir
    • Phoenix
    • Ecto
  • Erlang
    • OpenTelemetry collaborator
    • EEF Member
    • OTP contributor
  • Nix/NixOS
  • Rust
  • PostgreSQL
  • sh/Bash
  • Ruby
    • Ruby on Rails

Technologies

  • Git
  • Vim
  • HashiStack
    • Terraform
    • Consul
    • Nomad
  • GNU/Linux and other UNIX-like systems
  • TDD/BDD methodologies
  • Property testing

Other

  • Viking reenactor
  • Keyboard fan
  • Sci-fi/Fantasy fan and Poznań's Sci-fi/Fantasy club member