the code

.gitignore

@@ -0,0 +1,2 @@
+.idea
+bin/*

cmd/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"github.com/valyala/fasthttp"
+	"log"
+)
+
+func main() {
+	if err := fasthttp.ListenAndServe(":8080", requestHandler); err != nil {
+		log.Fatalf("Error in ListenAndServe: %v", err)
+	}
+}
+
+func requestHandler(ctx *fasthttp.RequestCtx) {
+	fmt.Fprintf(ctx, "Hello, world!\n\n")
+
+	fmt.Fprintf(ctx, "Request method is %q\n", ctx.Method())
+	fmt.Fprintf(ctx, "RequestURI is %q\n", ctx.RequestURI())
+	fmt.Fprintf(ctx, "Requested path is %q\n", ctx.Path())
+	fmt.Fprintf(ctx, "Host is %q\n", ctx.Host())
+	fmt.Fprintf(ctx, "Query string is %q\n", ctx.QueryArgs())
+	fmt.Fprintf(ctx, "User-Agent is %q\n", ctx.UserAgent())
+	fmt.Fprintf(ctx, "Connection has been established at %s\n", ctx.ConnTime())
+	fmt.Fprintf(ctx, "Request has been started at %s\n", ctx.Time())
+	fmt.Fprintf(ctx, "Serial request number for the current connection is %d\n", ctx.ConnRequestNum())
+	fmt.Fprintf(ctx, "Your ip is %q\n\n", ctx.RemoteIP())
+
+	fmt.Fprintf(ctx, "Raw request is:\n---CUT---\n%s\n---CUT---", &ctx.Request)
+
+	ctx.SetContentType("text/plain; charset=utf8")
+
+	ctx.Response.Header.Set("X-My-Header", "my-header-value")
+
+	var c fasthttp.Cookie
+	c.SetKey("cookie-name")
+	c.SetValue("cookie-value")
+	ctx.Response.Header.SetCookie(&c)
+}

go.mod

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+module demosite
+
+go 1.19
+
+require github.com/valyala/fasthttp v1.44.0
+
+require (
+	github.com/andybalholm/brotli v1.0.4 // indirect
+	github.com/klauspost/compress v1.15.15 // indirect
+	github.com/valyala/bytebufferpool v1.0.0 // indirect
+)

go.sum

@@ -0,0 +1,22 @@
+github.com/andybalholm/brotli v1.0.4 h1:V7DdXeJtZscaqfNuAdSRuRFzuiKlHSC/Zh3zl9qY3JY=
+github.com/andybalholm/brotli v1.0.4/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
+github.com/klauspost/compress v1.15.9/go.mod h1:PhcZ0MbTNciWF3rruxRgKxI5NkcHHrHUDtV4Yw2GlzU=
+github.com/klauspost/compress v1.15.15 h1:EF27CXIuDsYJ6mmvtBRlEuB2UVOqHG1tAXgZ7yIO+lw=
+github.com/klauspost/compress v1.15.15/go.mod h1:ZcK2JAFqKOpnBlxcLsJzYfrS9X1akm9fHZNnD9+Vo/4=
+github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
+github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
+github.com/valyala/fasthttp v1.44.0 h1:R+gLUhldIsfg1HokMuQjdQ5bh9nuXHPIfvkYUu9eR5Q=
+github.com/valyala/fasthttp v1.44.0/go.mod h1:f6VbjjoI3z1NDOZOv17o6RvtRSWxC77seBFc2uWtgiY=
+github.com/valyala/tcplisten v1.0.0/go.mod h1:T0xQ8SeCZGxckz9qRXTfG43PvQ/mcWh7FwZEA7Ioqkc=
+golang.org/x/crypto v0.0.0-20220214200702-86341886e292/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20220906165146-f3363e06e74c/go.mod h1:YDH+HFinaLZZlnHAfSS6ZXJJ9M9t4Dl22yv3iI2vPwk=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220728004956-3c1f35247d10/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=