Mock server for load testing

dockerfile

FROM golang:1.11.10-alpine3.9 as builder

# installing git
RUN apk update && apk upgrade && \
    apk add --no-cache git

# setting working directory
WORKDIR /go/src/app

# installing dependencies
RUN go get github.com/sirupsen/logrus
RUN go get github.com/buaazp/fasthttprouter
RUN go get github.com/valyala/fasthttp

COPY / /go/src/app/
RUN go build -o mock

FROM alpine:3.9

WORKDIR /go/src/app
COPY --from=builder /go/src/app/mock /go/src/app/mock

COPY *.json /app/mocks/

EXPOSE 80

CMD ["./mock"]

main.go

package main

import (
	"fmt"
	"os"
	"time"
	"io/ioutil"
	"log"
	"github.com/buaazp/fasthttprouter"
	"github.com/valyala/fasthttp"
)

var searchMock []byte

func Mock(ctx *fasthttp.RequestCtx) {
	fmt.Println("mocked!")
	ctx.Response.Header.Set("Content-Type", "application/json")
	time.Sleep(700 * time.Millisecond)
	ctx.Write(searchMock);
}
func main() {
    
	m, e := ioutil.ReadFile("/app/mocks/response.json")
	if e != nil {
		fmt.Printf("Error reading mock file: %v\n", e)
		os.Exit(1) 
	}
	searchMock = m

	fmt.Println("starting...")

	router := fasthttprouter.New()
	router.POST("/", Mock)
	
	log.Fatal(fasthttp.ListenAndServe(":80", router.Handler))

}

response.json

{
    "glossary": {
        "title": "example glossary",
		"GlossDiv": {
            "title": "S",
			"GlossList": {
                "GlossEntry": {
                    "ID": "SGML",
					"SortAs": "SGML",
					"GlossTerm": "Standard Generalized Markup Language",
					"Acronym": "SGML",
					"Abbrev": "ISO 8879:1986",
					"GlossDef": {
                        "para": "A meta-markup language, used to create markup languages such as DocBook.",
						"GlossSeeAlso": ["GML", "XML"]
                    },
					"GlossSee": "markup"
                }
            }
        }
    }
}