---
title: "Counting to 3 with a new builder processing 50M+ monthly builds"
url: https://daily.dev/posts/counting-to-3-with-a-new-builder-processing-50m-monthly-builds-uvavj2xjm
source_url: https://blog.railway.com/p/new-builder-scale-big
type: article
source: "Railway Blog"
published: 2026-05-14T19:47:34.637Z
updated: 2026-05-14T19:47:56.504Z
tags: ["docker"]
reading_time: 10
upvotes: 5
comments: 0
language: en
---

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# Counting to 3 with a new builder processing 50M+ monthly builds

**[Railway Blog](https://daily.dev/sources/railway-blog)** · 10 min read · 5 upvotes · 0 comments

## Summary

Railway replaced its Docker-buildx GCP autoscaler with a fleet of microVM build cells running BuildKit on bare-metal hosts, now processing 66,000 builds per hour at peak. The post details the full engineering journey: a standalone binary refactor that collapsed four layers into one process (cutting ~20s from cached builds), networking failures from VM bridge issues, cgroup v2 isolation to fix stuck builds caused by runc workers starving buildkitd, and a 10-second optimization from reading OCI manifest metadata instead of decompressing image layers. The migration spanned GCP and AWS before landing on bare-metal, with the egress problem now resolved.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://blog.railway.com/p/new-builder-scale-big>

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---

Tags: [#docker](https://daily.dev/tags/docker)

[View this post on daily.dev](https://daily.dev/posts/counting-to-3-with-a-new-builder-processing-50m-monthly-builds-uvavj2xjm)