Monorepo for Tangled
blog: gentler intro to spindles
Signed-off-by: oppiliappan <me@oppi.li>
oppiliappan
(Jun 30, 2026, 12:43 PM +0100)
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blog/posts/spindle-microvm.md
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blog/posts/spindle-microvm.md
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handle: ptr.pet
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---
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Our CI service now supports a new engine: `microvm`. If you're new here, our CI
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runners -- [spindles](/ci) -- support a pluggable interface for workflow
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execution. Until now, our flagship instance at spindle.tangled.sh only
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supported a [Nixery-based
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engine](https://docs.tangled.org/spindles#nixery-engine).
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Spindles are the self-hostable CI runners. It now supports a
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new mode of execution using QEMU MicroVMs. With the new
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microVM engine, each workflow gets its own little virtual
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machine, a whole real environment you can do anything
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inside.
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Now, with the new microVM engine, each workflow gets its own little virtual
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machine, a whole real environment you can do anything inside. It's an upgrade
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from the Nixery engine while staying fully compatible with it, so if you
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already have a working Nixery workflow, just change `nixery` to `microvm` and
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it will work!
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The interesting part is NixOS images: you configure the machine directly from
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the workflow file. A few things you can do:
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The interesting part is NixOS images: you configure the
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machine directly from the workflow file. A few things you
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can do:
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You can bring services up:
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···
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command: docker build ...
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```
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And you can use non-NixOS images too:
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And you can use non-NixOS images:
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```yaml
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image: alpine
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- name: install golang
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command: apk add go
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```
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It's an upgrade from the existing Nixery engine while
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staying fully compatible with it, so if you already have a
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working Nixery workflow, just change `nixery` to `microvm`
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and it will work!
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It's quick on the second run, too, because it caches aggressively: your
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dependencies, your services, and any other Nix derivation built inside the