Upgrade to go 1.16 and use embed module

assets-dev.go

@@ -0,0 +1,32 @@
+//go:build dev
+// +build dev
+
+package main
+
+import (
+	"flag"
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+var (
+	Assets    http.FileSystem
+	StaticDir string = "static/"
+)
+
+func init() {
+	flag.StringVar(&StaticDir, "static", StaticDir, "Directory containing static files")
+}
+
+func sanitizeStaticOptions() error {
+	StaticDir, _ = filepath.Abs(StaticDir)
+	if _, err := os.Stat(StaticDir); os.IsNotExist(err) {
+		StaticDir, _ = filepath.Abs(filepath.Join(filepath.Dir(os.Args[0]), "static"))
+		if _, err := os.Stat(StaticDir); os.IsNotExist(err) {
+			return err
+		}
+	}
+	Assets = http.Dir(StaticDir)
+	return nil
+}