Function scanFile

scripts/metricsdocgen/scanner/scanner.go:191–228

scanFile parses a single Go file and extracts all Prometheus metric definitions.

(path string)

// scanFile parses a single Go file and extracts all Prometheus metric definitions.
func scanFile(path string) ([]Metric, error) {
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, path, nil, parser.SkipObjectResolution)
	if err != nil {
		return nil, xerrors.Errorf("parsing file: %w", err)
	}

	// Collect exported constants into the global package declarations map.
	collectPackageConsts(file)

	// Collect file-local const and var declarations for resolving references.
	decls := collectDecls(file)

	var metrics []Metric

	// Walk the AST looking for metric registration calls.
	ast.Inspect(file, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if !ok {
			return true
		}

		metric, ok := extractMetricFromCall(call, decls)
		if ok {
			if metric.Help == "" {
				warnf("metric %q has no HELP description, skipping", metric.Name)
				// Skip metrics without descriptions, they should be fixed in the source code
				// or added to the static metrics file with a manual description.
				return true
			}
			metrics = append(metrics, metric)
		}

		return true
	})

	return metrics, nil
}

// collectPackageConsts collects exported string constants from a file into
// the global packageDeclarations map, keyed by package name.