【Go】HTTP/2 サーバーをデバッグモードで動かす

サーバーの起動時に環境変数 GODEBUG を設定する

GODEBUG=http2debug=2 go run server.go

ほかにHTTP/2 を無効にすることもできる

GODEBUG=http2server=0 go run server.go

server.go

package main

import (
    "fmt"
    "net/http"
)

func helloHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, world!\r\n")
}

func main() {
    http.HandleFunc("/", helloHandler)
//    http.ListenAndServe(":8000", nil)
    http.ListenAndServeTLS(":8080", "localhost.pem", "localhost-key.pem", nil)
}

curl で GET リクエストを送信すると次のようにログを表示してくれる

2024/07/05 10:48:51 http2: server connection from 127.0.0.1:44164 on 0xc000142000
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: wrote SETTINGS len=30, settings: MAX_FRAME_SIZE=1048576, MAX_CONCURRENT_STREAMS=250, MAX_HEADER_LIST_SIZE=1048896, HEADER_TABLE_SIZE=4096, INITIAL_WINDOW_SIZE=1048576
2024/07/05 10:48:51 http2: server: client 127.0.0.1:44164 said hello
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: read SETTINGS len=18, settings: MAX_CONCURRENT_STREAMS=100, INITIAL_WINDOW_SIZE=33554432, ENABLE_PUSH=0
2024/07/05 10:48:51 http2: server read frame SETTINGS len=18, settings: MAX_CONCURRENT_STREAMS=100, INITIAL_WINDOW_SIZE=33554432, ENABLE_PUSH=0
2024/07/05 10:48:51 http2: server processing setting [MAX_CONCURRENT_STREAMS = 100]
2024/07/05 10:48:51 http2: server processing setting [INITIAL_WINDOW_SIZE = 33554432]
2024/07/05 10:48:51 http2: server processing setting [ENABLE_PUSH = 0]
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: read WINDOW_UPDATE len=4 (conn) incr=33488897
2024/07/05 10:48:51 http2: server read frame WINDOW_UPDATE len=4 (conn) incr=33488897
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: read HEADERS flags=END_STREAM|END_HEADERS stream=1 len=30
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: wrote SETTINGS flags=ACK len=0
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: wrote WINDOW_UPDATE len=4 (conn) incr=983041
2024/07/05 10:48:51 http2: decoded hpack field header field ":method" = "GET"
2024/07/05 10:48:51 http2: decoded hpack field header field ":path" = "/"
2024/07/05 10:48:51 http2: decoded hpack field header field ":scheme" = "https"
2024/07/05 10:48:51 http2: decoded hpack field header field ":authority" = "localhost:8080"
2024/07/05 10:48:51 http2: decoded hpack field header field "user-agent" = "curl/7.88.1"
2024/07/05 10:48:51 http2: decoded hpack field header field "accept" = "*/*"
2024/07/05 10:48:51 http2: server read frame HEADERS flags=END_STREAM|END_HEADERS stream=1 len=30
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: read SETTINGS flags=ACK len=0
2024/07/05 10:48:51 http2: server read frame SETTINGS flags=ACK len=0
2024/07/05 10:48:51 http2: server encoding header ":status" = "200"
2024/07/05 10:48:51 http2: server encoding header "content-type" = "text/plain; charset=utf-8"
2024/07/05 10:48:51 http2: server encoding header "content-length" = "15"
2024/07/05 10:48:51 http2: server encoding header "date" = "Fri, 05 Jul 2024 01:48:51 GMT"
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: wrote HEADERS flags=END_HEADERS stream=1 len=49
2024/07/05 10:48:51 http2: Framer 0xc00013e2a0: wrote DATA flags=END_STREAM stream=1 len=15 data="Hello, world!\r\n"