Move flags and metrics into main()

Fixes #933.

Signed-off-by: beorn7 <beorn@grafana.com>

examples/random/main.go

@@ -29,6 +29,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
+func main() {
 	var (
 		addr              = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
 		uniformDomain     = flag.Float64("uniform.domain", 0.0002, "The domain for the uniform distribution.")
@@ -37,6 +38,8 @@ var (
 		oscillationPeriod = flag.Duration("oscillation-period", 10*time.Minute, "The duration of the rate oscillation period.")
 	)
 
+	flag.Parse()
+
 	var (
 		// Create a summary to track fictional interservice RPC latencies for three
 		// distinct services with different latency distributions. These services are
@@ -60,16 +63,11 @@ var (
 		})
 	)
 
-func init() {
 	// Register the summary and the histogram with Prometheus's default registry.
 	prometheus.MustRegister(rpcDurations)
 	prometheus.MustRegister(rpcDurationsHistogram)
 	// Add Go module build info.
 	prometheus.MustRegister(prometheus.NewBuildInfoCollector())
-}
-
-func main() {
-	flag.Parse()
 
 	start := time.Now()