Senior Backend Engineer (Ruby or Golang), Tenant Scale; Cells Infrastructure

As a Senior Backend Engineer on the Cells Infrastructure team, you'll help build the foundation that allows GitLab.com to scale horizontally through our Cells architecture. This is a critical infrastructure project focused on moving away from a single large cluster toward a fleet of independent Cell clusters.

You'll work on two core pillars of this system:

1. Edge Routing Services: Directing traffic across independent Cell clusters in a way that is transparent to the user.

2. Topology Service: Managing and serving the cluster topology information that acts as the source of truth for the entire platform.

This role is ideal for engineers who enjoy solving complex distributed systems problems, including partitioning strategies, high-throughput networking, and low-latency service design.

What You’ll Do

• Design Edge Routing: Implement routing services (built in TypeScript) that direct requests to the correct Cell cluster based on topology data.

• Evolve Topology Service: Build and maintain the authoritative source of cluster state used for routing, resource assignment, and Cell lifecycle decisions.

• Cross-Platform Collaboration: Work across the GitLab Rails monolith and supporting services to help feature teams make their data models "Cell-aware."

• Operational Ownership: Participate in tier-2 on-call rotations, respond to escalated incidents, and strengthen observability for the systems you build.

• Technical Documentation: Author Architecture Decision Records (ADRs) and operational runbooks to enable other teams to adopt and extend the Cells platform.

• Code Quality: Review merge requests from team members and the community, maintaining high standards for performance and security.

What You’ll Bring

• Backend Expertise: Experience building resilient production services using Go or Ruby on Rails (TypeScript experience is a significant plus).

• Distributed Systems Knowledge: Ability to reason about consistency models, partitioning strategies, failure modes, and operational tradeoffs at scale.

• High-Scale Operations: A background in operating high-scale systems, including incident response and building observable infrastructure (metrics, tracing, alerting).

• Networking Fundamentals: Experience building high-throughput networking services; knowledge of gRPC and Protocol Buffers is a plus.

• Database Proficiency: Experience with relational databases in production, specifically PostgreSQL, including schema design and query tuning.

• Collaborative Mindset: Strong written communication for an async-first environment and experience coordinating technical changes across large, multi-team codebases.

About the Team

We are the Cells Infrastructure team, a globally distributed group of Backend Engineers and Site Reliability Engineers. Our challenge is to ensure GitLab.com can continue to grow safely by making horizontal scaling reliable and low-latency. We value asynchronous work, clear documentation, and building systems that we are confident operating on-call.