registry: use consts for some defaults

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

registry/registry.go

@@ -72,15 +72,16 @@ var defaultCipherSuites = []uint16{
 	tls.TLS_AES_256_GCM_SHA384,
 }
 
-// maps tls version strings to constants
-var (
-	defaultTLSVersionStr = "tls1.2"
-	tlsVersions          = map[string]uint16{
-		// user specified values
+const defaultTLSVersionStr = "tls1.2"
+
+// tlsVersions maps user-specified values to tls version constants.
+var tlsVersions = map[string]uint16{
 	"tls1.2": tls.VersionTLS12,
 	"tls1.3": tls.VersionTLS13,
-	}
-)
+}
+
+// defaultLogFormatter is the default formatter to use for logs.
+const defaultLogFormatter = "text"
 
 // this channel gets notified when process receives signal. It is global to ease unit testing
 var quit = make(chan os.Signal, 1)
@@ -131,6 +132,7 @@ var ServeCmd = &cobra.Command{
 }
 
 // A Registry represents a complete instance of the registry.
+//
 // TODO(aaronl): It might make sense for Registry to become an interface.
 type Registry struct {
 	config *configuration.Configuration
@@ -347,7 +349,7 @@ func configureLogging(ctx context.Context, config *configuration.Configuration)
 
 	formatter := config.Log.Formatter
 	if formatter == "" {
-		formatter = "text" // default formatter
+		formatter = defaultLogFormatter
 	}
 
 	switch formatter {