HTTP/2 over TCP

h2c.go

package main

import (
	"net/http"

	"github.com/labstack/echo/v4"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
)

func main() {
	e := echo.New()

	h2s := &http2.Server{}

	e.Server = &http.Server{
		Addr:    ":5555",
		Handler: h2c.NewHandler(e, h2s),
	}

	e.GET(".ok", func(c echo.Context) error {
		return c.String(200, "ok")
	})

	e.Server.ListenAndServe()
}

https://echo.labstack.com/docs/start-server#http2-cleartext-server-http2-over-http ドキュメントがあった orz