runner-up: Open-source tool for ephemeral self-hosted GitHub Actions runners

X postKun ChenTool

Kun Chen has released runner-up, an open-source tool designed to self-host GitHub Actions runners across owned hardware. It spins up an ephemeral VM or container for each CI job across Linux, macOS, and Windows, automatically destroying it after execution.

Key points

  1. Complete job isolation: Uses KVM or Docker on Linux, Tart or Apple containers on macOS, and Hyper-V or dedicated accounts on Windows.
  2. Zero state bleed: Micro-VMs and containers are cleanly destroyed after use, preventing leftover artefacts across PR builds.
  3. Alternative to Kubernetes: Built specifically to avoid the complexity of managing a K8s cluster for self-hosted CI.
  4. SSH-driven coordinator: A single coordinator interacts with GitHub via runner scale sets and launches single-job runners over SSH.
  5. Security and resilience: Rejects fork pull requests by default; automatically reroutes incoming jobs away from offline nodes.

Why it matters

Cloud CI minutes—especially for macOS runners—can quickly generate massive bills for projects running thousands of jobs daily. runner-up allows teams to leverage idle physical hardware while maintaining clean, ephemeral environments without high cloud overhead.

Analysis

runner-up addresses the middle ground between high-maintenance Kubernetes runner controllers and fragile, persistent self-hosted setups. By abstracting native hypervisors and container engines (such as Tart on macOS and KVM on Linux), it prevents dirty workspaces and security leaks between builds. The coordinator hooks into GitHub's runner scale set architecture, ensuring efficient queuing and dynamic resource budgeting.

Original post

Kun Chen

@kunchenguid · 4 November 2026

just published a free OSS tool "runner-up" t.co/1K33H04XZE which is the setup i've been using to self-host all my github actions runners across my own machines i run thousands of CI jobs every day on private repos. they would have cost me about $5000-$9000/mo depending

342 likes36 replies420 bookmarks13.2k views

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More posts in the thread (5)
  1. @jgoon0 yes repo readme actually explained why i did this over k8s
  2. @kartikb753 yes each runner can run in a micro-vm which gets completely destroyed after use so zero pile up and maintenance
  3. @chenzhangreal mac jobs are disgustingly expensive
  4. @mad_guy888 no because that’s github actions and application layer concern but it will automatically route future jobs to the machines that are still up
  5. @thisishars @kartikb753 i actually often reply even when i knew it’s likely ai but i thought the answer would be helpful for some other people regardless
Selected replies (5)
  • @ayushvatsa18 @kunchenguid I actually bought a ec2 instance yesterday(until my new MacBook arrives) to run github actions. Configured it in a way so that i can run my secondmate and gh actions both on cloud. And you are right about the cost, owning your own hardware makes much sense now.
  • @jgoon0 @kunchenguid out of curiosity did you consider using k8s here? or is this setup more suited for machines that were being used for agent runs already
  • @Xinzz995 @kunchenguid 男菩萨🥰
  • @pathinthefog @kunchenguid @bot spin up thread on 3R and check if relevant for us
  • @chenzhangreal @kunchenguid thousands of CI jobs a day costing up to $9k a month? that’s wild, no wonder you built this.

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Summary generated by AI (Gemini 3.8 Flash, 4 November 2026). It may contain errors – the original source is authoritative.

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