runs-on: fast, cheap, self-hosted GitHub Action runners

runs-on is a service that dynamically launches powerful hosted runners of any size, for any GitHub repository.

In your GitHub Action workflow files, instead of using the default base runner:

runs-on: ubuntu-latest

You would use:

runs-on: [self-hosted,aws,ubuntu-22,x64,16cpu,32ram]

And then your workflow will execute with a 16 vCPUs / 32GB RAM instance. After the workflow ends, the instance will automatically terminates.

Make that slow test suite fly

GitHub provides base runners with a most 8GB of RAM and 2vCPUs. Bigger runners are available, but they require a Team or Enterprise plan, as well as not being cheap (e.g. a 16 core linux VM is sold at $0.064/min, i.e. theoretical cost of $2700/month if fully used).

From various experiences at smaller companies, I believe there is a need to provide a simple service that auto-magically provision runners of various sizes (and architectures?), for a much cheaper price than what GitHub provides.

Ephemeral self-hosted runners, in your own AWS account

We can use the workflow events emitted by GitHub to auto-provision runners, on-premise:

• You deploy the service on a single server within your infrastructure, in a fire and forget manner.
• The service connects to any of your GitHub repositories, and listens for incoming workflow events.
• When a workflow specifies a custom runner, it provisions an on-demand VM, in your own cloud provider account.

From start to end, everything (service + VMs) runs in your own infrastructure, which is a big win in terms of security and observability.

AWS will be the first provider to be supported: with spot pricing, per-minute billing and large choice of instance types and architectures, it is very efficient in terms of cost/performance for CI workflows.

Hetzner would be the next clear choice, since their cloud offering has a great performance/price ratio (although no per-minute billing).

Design choices

• Service can be launched with a single command, and runs on a $5 VM.
• Service must make it easy to connect a GitHub account, and add specific GitHub repositories to listen to.
• Service exposes a simple UI for management and observability purposes. HTTPS is required.
• Service allows you to specify a max monthly bill. Runners are no longer started once this limit is reached.

Pricing

The code will be open-source, possibly with a commercial license required after 30+ days of use. This formula seems to work well for my other project PullPreview.

Installation (coming soon)

Service is compatible with any server running Ubuntu 22.04 LTS. A domain (e.g. runners.example.com) must point to the server. We strongly recommend using a dedicated VM for that service.

1. Download the script:

   curl -O https://runs-on.com/install.sh

2. Inspect the script to ensure it's safe to run.
3. Run the script with the required arguments:

   sudo sh ./install.sh --domain runners.example.com