Allow configuring log format.

In a production environment the timestamp will be appended by the log
service.

src/config.go

@@ -12,7 +12,8 @@ type CacheConfig struct {
 }
 
 type Config struct {
-	Listen struct {
+	LogFormat string `toml:"log-format"`
+	Listen    struct {
 		Pages  string `toml:"pages"`
 		Caddy  string `toml:"caddy"`
 		Health string `toml:"health"`

src/main.go

@@ -41,6 +41,13 @@ func main() {
 	}
 	UpdateConfigEnv() // environment takes priority
 
+	switch config.LogFormat {
+	case "short":
+		log.SetFlags(0)
+	default:
+		log.SetFlags(log.Ldate | log.Ltime | log.LUTC)
+	}
+
 	switch config.Backend.Type {
 	case "fs":
 		if backend, err = NewFSBackend(config.Backend.FS.Root); err != nil {