Blacksmith vs GitHub Runner Demo

A minimal demo repository for comparing GitHub-hosted runners against Blacksmith runners on an identical CI workload.

The CI pipeline is a realistic-but-small Node/TypeScript job:

1. npm ci — dependency install (network + disk I/O)
2. npm run build — TypeScript compile
3. npm test — Jest suite with deliberately CPU-heavy tests (prime sieve, SHA-256 hash chains, PBKDF2, naive matrix multiplication)
4. npm run bench — a timed CPU benchmark that prints per-task wall-clock times, so you can compare raw compute between runners directly in the logs

How to run the demo

Step 1 — Baseline on GitHub runners

The workflow ships pointing at GitHub's hosted runner:

runs-on: ubuntu-latest

Trigger a run (push a commit, or use the Run workflow button — the workflow has workflow_dispatch enabled) and note the total job duration and the benchmark step output.

Step 2 — Switch one line to Blacksmith

Prerequisite: install the Blacksmith GitHub App on this repository (takes ~1 minute).

Then edit .github/workflows/ci.yml and swap the single runs-on line:

-    runs-on: ubuntu-latest
+    runs-on: blacksmith-4vcpu-ubuntu-2404

Push the change and compare:

• Total job duration (Actions run summary)
• Queue time (time from trigger to job start)
• Per-step timings (install / build / test)
• Benchmark output (raw single-core and multi-task CPU times)

blacksmith-4vcpu-ubuntu-2404 matches the 4 vCPUs of GitHub's free ubuntu-latest runner for a fair comparison. Other sizes (blacksmith-2vcpu-…, blacksmith-8vcpu-…, etc.) are also available.

Running locally

npm ci
npm run build
npm test
npm run bench