A Go package to pre-compiles and register all the templates in a directory and it's subdirectories. FYI – this won't be a suitable approach if you have same file names in subdirectories!

template.go

package template

import (
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	"github.com/labstack/echo/v4"
)

// Template implements echo.Renderer interface.
type Template struct {
	templates *template.Template
}

// NewTemplate pre-compiles and registers templates in given directory.
func NewTemplate(viewsDir, tmplFileExtension string) *Template {
	return &Template{
		templates: registerTemplates(viewsDir, tmplFileExtension),
	}
}

// Render renders a template with given data.
func (t *Template) Render(w io.Writer, name string, data interface{}, c echo.Context) error {
	if err := t.templates.ExecuteTemplate(w, name, data); err != nil {
		fmt.Println(err)
		return err
	}

	return nil
}

// registerTemplates is a helper func to walk the views directory
// and register each file with *template.Template.
func registerTemplates(viewsDir, tmplFileExtension string) *template.Template {
	tpl := template.New("")

	err := filepath.Walk(viewsDir, func(path string, info os.FileInfo, err error) error {
		if strings.Contains(path, tmplFileExtension) {
			_, err = tpl.ParseFiles(path)
			if err != nil {
				log.Println(err)
			}
		}
		return err
	})
	if err != nil {
		panic(err)
	}

	return tpl
}