Function isCustomImageRunner

pkg/workflow/runtime_detection.go:340–355

isCustomImageRunner returns true if the runs-on configuration indicates a non-standard runner (custom image, self-hosted runner, or runner group). Custom image runners may not have Node.js pre-installed, so the compiler ensures Node.js is set up. Only the labels in standardGitHubHostedRunners are c

(runsOn string)

//   - "runs-on:\n- self-hosted\n..."  → array form      → returns true
//   - "runs-on:\n  group: ..."        → object form     → returns true
func isCustomImageRunner(runsOn string) bool {
	if runsOn == "" {
		// Empty means the default "ubuntu-latest" will be applied — not a custom runner.
		return false
	}

	const keyPrefix = "runs-on: "
	if value, ok := strings.CutPrefix(runsOn, keyPrefix); ok {
		// Single-line value: check the label against the known-standard allowlist.
		value = strings.TrimSpace(strings.ToLower(value))
		return !standardGitHubHostedRunners[value]
	}

	// Multi-line value (array or object form) — always treat as custom image runner.
	return true
}