Senior Platform Infrastructure Engineer

Job Overview

Senior Platform Infrastructure Engineer - Mercari
Employment Status: Full-time
Work Hours: Full Flextime (no core time)
Office: Roppongi (hybrid)
For more details, see the Overview of Our Positions section on our Careers site.

About Mercari

\"Circulate all forms of value to unleash the potential in all people\"
\"What can I do to help society thrive with the finite resources we have?\" The Mercari marketplace app was born in 2013 out of this thought by our founder Shintaro Yamada as he traveled the world. We believe that by circulating all forms of value, not just physical things and money, we can create opportunities for anyone to realize their dreams and contribute to society and the people around them. Mercari aims to use technology to connect people all over the world and create a world where anyone can unleash their potential. For more information about Mercari Group’s mission, see Mercari’s Culture Doc

Organization/Team Mission

Mercari Engineering Principles
Mercari Engineering Principles are a shared understanding that serves as the foundation of engineering beliefs and behavior at Mercari. The Engineering Principles are designed to complement the organizational identity (Mercari’s mission, values, and culture) from an engineering viewpoint.
These principles ultimately help us achieve Mercari’s mission by defining the ideal state we seek to realize in the long term.
Passion For The Product
Grow Together
Solve Through Mechanisms
Collaborate Openly
For more details, please see the following link:
Engineering Culture
The Autonomous Cloud group in the Platform Division builds and operates the foundational infrastructure that lets every engineering team at Mercari ship products safely and quickly - covering the Kubernetes platform, search infrastructure, observability, networking, and FinOps. Our charter is to make complex infrastructure simple to consume, so product teams can spend their time on customer value rather than on running systems.
The Platform Infrastructure team - part of the Autonomous Cloud division - runs Mercari's Kubernetes platform and Infrastructure-as-Code as a managed service for engineering teams across the company. We operate the GKE clusters that host most of Mercari's microservices, own the Terraform code that provisions and evolve them, and build the developer-facing \"kits\" that let hundreds of engineers spin up new microservices and on-call setup in minutes rather than days. Our job is to abstract away the operational complexity of the platform so product teams can focus on building features. We are a team that combines hands-on operation of the clusters with deep expertise in Kubernetes internals and IaC-at-scale - partnering closely with Search Infra, Network, Observability, FinOps, DBRE, and Enablement teams.
See here for more information about our mission and values.

Work Responsibilities

Co-own the GKE cluster lifecycle: upgrades, node-pool strategy, add-on management (Cert Manager, autoscaling, workload identity), capacity planning, and incident response.
Own and evolve the Terraform IaC: custom modules, large-blast-radius migrations, and the Terraform CI/CD that keeps changes safe at scale - drift detection, staged rollout, revert planning, and pipeline reliability.
Build and maintain \"kits\" - reusable Terraform modules and self-service tooling that let product teams provision repos (with CODEOWNERS), PagerDuty, GitHub Actions workflows, and deployment pipelines without infra hand-holding.
Own autoscaling and capacity at scale: Cluster Autoscaler / HPA / VPA, cost-aware right-sizing, and multi-region and node-pool strategies for large workloads.
Ship internal developer-platform components in Go: k8s controllers, CLIs and internal APIs, and AI agent skills that cut friction on the most-used developer paths.
Join the Platform on-call rotation after ramp-up; lead root-cause analysis and follow-through improvements.
Drive reliability, security, and developer-experience initiatives in partnership with FinOps, Network, Observability, DBRE, and Enablement teams.

Unique Challenges

Kubernetes at multi-tenant scale - We run GKE clusters that host hundreds of microservices deployed by teams across the company. Node-pool strategy (autoscaling, spot, ARM diversification), control-plane and add-on upgrade cadence, and workload isolation are everyday work. Every change to a shared Terraform module, a GKE add-on, or a kit touches all of those services at once, so getting the design and the rollout right up-front is a core part of the job.
Custom controllers, admission policy, and add-on ownership - A meaningful part of the platform is our own Kubernetes controllers, admission webhooks, and policy layer (RBAC, network policies, OPA / Gatekeeper) that keep a multi-tenant cluster safe and predictable. You design and run these, not just consume upstream.
Multi-region and multi-architecture roadmap - We are actively expanding to a multi-region topology and adopting different k8s node-types for cost and capacity headroom. You will help shape this rollout.
Developer-experience as an SLI - The self-service kits are used every day by product engineers. A regression in a kit shows up as friction across the whole engineering org, so we take DX seriously as a reliability signal, not a nice-to-have.
Cross-team ownership - Platform Infra sits between application teams, cloud providers, and peer infra teams (Search, Network, Observability, FinOps, DBRE, Enablement). Success in this role requires investing substantial time in cross-team architecture, shared platform capabilities, and organizational alignment not just work within your own team.

Qualifications

Required Experience/Skills
Shared belief in Mercari's mission and values.
Senior-level engineering experience operating distributed systems in produc