utils.go

func renderTemplate(fs fs.FS, file string
                            , args interface{}) bytes.Buffer {
  var tpl bytes.Buffer
  // read the block-kit definition as a go template
  t, err := template.ParseFS(fs, file)
  if err != nil {
    panic(err)
  }
  // render the template using provided datas
  err = t.Execute(&tpl, args)
  if err != nil {
    panic(err)
  }
  return tpl
}