Hey there, Kubernetes people Hundreds of developers push to a large Ruby on Rails monorepo, and every push lands on a runner fleet that the Developer Experience team builds, runs and keeps fast.
That fleet is self-hosted Kubernetes on bare metal in European datacentres, in the low hundreds of machines, running eternal GitHub Actions runners that peak above a thousand concurrent pods. We own all of it: the hardware, the clusters, the runner images, the caches and the delivery pipelines on top. We add nodes by hand rather than letting an autoscaler do it, so capacity planning is genuinely part of the job.
Shave a minute off the average build and every engineer in the company gets that minute back, several times a day.
Own the CI and CD Kubernetes clusters end to end: capacity, reliability, upgrades, security and cost.
Run the self-hosted GitHub Actions platform at scale with Actions Runner Controller. Runner scale sets, ephemer pods, docker-in-docker, and the runner images themselves.
Keep the data services our tests depend on fast and healthy. MySQL,



Redis and ClickHouse come up per job, alongside Rails application containers.
Design and tune the caching that makes builds quick: node-local overlay, image and artifact caches we build ourselves, plus pull-through registry mirrors.
Bring queue wait and build duration down, with measurement behind it. Manage it all as code. Terraform planned and applied from pull requests, GitOps delivery with Flux and Argo CD, Kustomize and Helm for manifests.
Provision and operate bare metal. Linux, networking across datacentre segments, and troubleshooting that sometimes ends up at the disk or the kernel.
Rightsizing runner tiers against a week of CPU and memory data, then opening the pull request that changes them.
Tracking a flaky job from a red check down to the container runtime, the kernel, or a clock that drifted.
Adding machines to the fleet: install, enrol, network, verify, document.
Cutting p95 queue wait by working out which

📌 Senior DevOps Engineer, CI/CD Platform (Barcelona)
🏢 Factorial Hr
📍 Barcelona