Jonathan ZIMPFER

Founded in 2016, Hivency is a platform that connects micro-influencers with brands.
I joined the startup a few months after it was founded, and progressed from Developer Ruby on Rails, SRE to CTO, via Lead developer, Lead SRE.

Developer Ruby on Rails, SRE

• - Development of the new platform version to ensure long-term maintainability
• - Migration of the existing database to a new schema better suited for future use
• - Creation of a real-time matching algorithm based on multiple dynamic criteria
• - Calculation of statistics derived from diverse data sources
• - Integration with networks and APIs (Instagram, YouTube, Google Analytics, Snapchat, etc.)
  
• - Management of the existing AWS-based infrastructure, specifically Elastic Beanstalk
• - Implementation of security and scalability best practices
• - Setup of a CI/CD pipeline using GitLab CI/CD

Lead developer, Lead SRE

• - Technical and code architecture lead
• - Participating in business meetings alongside the Product Owner to gather requirements, estimate complexity, and draft functional tickets
• - Participating in the hiring of new developers for the team
• - Onboarding new team members and facilitating knowledge transfer
• - Guiding the team in developing new features
• - Supporting the team in adopting new technologies or processes
• - Creating scripts and applications, and implementing tools to improve developers' daily workflows
• - Maintaining features I personally developed
  
• - Migrating the platform to GCP
• - Containerizing the platform with Docker for deployment on Kubernetes
• - Implementing Terraform for GCP infrastructure management

CTO

• - Successfully implemented remote work for the development team a few months prior to the COVID period
• - Introduced "Free Friday" (every other Friday) to allow the team to train on technical or non-technical topics
• - Participated in strategic meetings with stakeholders
  
• - Budgeted for technical projects and cloud infrastructure

Stack: Ruby on Rails, RSpec, PostgreSQL, ElasticSearch, Python, Docker, AWS, GCP, Kubernetes, Terraform, Gitlab, Gitlab CI/CD, ArgoCD, OpenTelemetry.

Launched in 2012, Quanta is a solution designed to improve website performance—particularly for e-commerce sites—with the aim of reducing infrastructure costs and boosting customer conversion rates by ensuring a smoother browsing experience.

• - Developed an internal web app to centralize recurring infrastructure tasks (such as creating VMs and database schemas), service configurations (e.g., LDAP), and employee onboarding/offboarding processes.
• - Managed bare-metal infrastructure hosted on Scaleway and the VMware ESX hypervisor.
• - Created a business intelligence program that takes lists of e-commerce URLs, gathers and categorizes data on them to identify the best prospects for the solution, and adds this data—along with information on key decision-makers—to the company's CRM.

Stack: Ruby on Rails, MariaDB, Django.

Sponkyfy is a command line tool that allows you to download playlists from Spotify and keep them up to date with regular synchronization. The aim is to be able to subsequently use this music during mixing/DJing sessions.
The music is also enriched via ID3 tags with the metadata made available by Spotify. Errors that may occur during synchronization, for example music no longer available, are managed and logged. The application keeps track of operations in an SQLite database, which allows it to update the playlists efficiently by discarding music already synchronized.
Skills: Python, SQLAlchemy, uv, Docker, Nix DevShell, reverse engineering, security, system administration.

Management of multiple server-type machines and the home network.
The homelab currently consists of the following components:

• - A server: AMD 4C/8T, 64 GB RAM, 70 TB storage
• - An Orange Pi 5 Plus mini PC: ARM 8C/8T, 16 GB RAM, 256 GB storage
• - A DIY router based on the Qotom Q20300S9: Intel Atom 8C/8T, 16 GB RAM, 256 GB storage, 4x SFP+ 10GbE, 5x RJ45 2.5GbE
• - A Wi-Fi access point: repurposed Linksys WRT1900AC v2 router running OpenWrt

Currently, most application services are managed via Docker Compose with Portainer as the front-end.
The next steps involve integrating the Wi-Fi access point into the router, migrating the server to Proxmox, and moving all services to a multi-node, multi-architecture Kubernetes cluster.
Skills: System administration, network administration, Docker.

Created a NixOS configuration to manage multiple machines.
Developed numerous modules to enable the modular installation of necessary packages and to extend Nix's core functionality.
The configuration currently manages my desktop/gaming rig, development laptop, and a custom-built router.
Next steps include using DevShell to manage project-specific development environments and handling VMs running on Proxmox and the mini PC.
Skills: NixOS, Nix, OS management, functional programming, networking, security.