## Auto TLS
這個例子演示如何自動從 Let's Encrypt 獲得 TLS 證書。 `Echo#StartAutoTLS` 接受一個接聽 443 端口的網絡地址。類似 `<DOMAIN>:443` 這樣。
如果沒有錯誤，訪問 `https://<DOMAIN>` ，可以看到一個 TLS 加密的歡迎界面。
### 服務器
`server.go`
```go
package main
import (
"net/http"
"github.com/labstack/echo"
"github.com/labstack/echo/middleware"
)
func main() {
e := echo.New()
// e.AutoTLSManager.HostPolicy = autocert.HostWhitelist("<your_domain>")
// Store the certificate to avoid issues with rate limits (https://letsencrypt.org/docs/rate-limits/)
// e.AutoTLSManager.Cache = autocert.DirCache("<path to store key and certificate>")
e.Use(middleware.Recover())
e.Use(middleware.Logger())
e.GET("/", func(c echo.Context) error {
return c.HTML(http.StatusOK, `
<h1>Welcome to Echo!</h1>
<h3>TLS certificates automatically installed from Let's Encrypt :)</h3>
`)
})
e.Logger.Fatal(e.StartAutoTLS(":443"))
}
```
