Go server that serves CSV files with random data

random_csv_server.go

package main

import (
	"encoding/csv"
	"fmt"
	"io/ioutil"
	"log"
	"math/rand"
	"net/http"
	"os"
)

func main() {
	err := os.MkdirAll("content", 0755)
	if err != nil {
		log.Fatal(err)
	}

	filesCount := 10
	for i := 1; i <= filesCount; i++ {
		records := generateCSV()
		if err := writeToFile(fmt.Sprintf("content/file%03d.csv", i), records); err != nil {
			log.Fatal(err)
		}
	}

	log.Fatal(serve("7000"))
}

func generateCSV() [][]string {
	cols := 5
	rows := 5
	wordSize := 8

	var records [][]string
	for i := 0; i < cols; i++ {
		records = append(records, randomStringArray(wordSize, rows))
	}
	return records
}

func randomStringArray(strLength, arrayLength int) []string {
	var letters = []rune("abcdefghijklmnopqrstuvwxyz")
	a := make([]string, arrayLength)
	for i := range a {
		b := make([]rune, strLength)
		for j := range b {
			b[j] = letters[rand.Intn(len(letters))]
		}
		a[i] = string(b)
	}
	return a
}

func writeToFile(name string, records [][]string) error {
	file, err := os.Create(name)
	if err != nil {
		return err
	}

	w := csv.NewWriter(file)
	w.WriteAll(records)

	if err := w.Error(); err != nil {
		return err
	}
	return nil
}

func serve(port string) error {
	http.HandleFunc("/random", func(res http.ResponseWriter, req *http.Request) {
		fileList, err := ioutil.ReadDir("content")
		if err != nil {
			return
		}

		file := fileList[rand.Intn(len(fileList))]

		if file.IsDir() {
			return
		}

		res.Header().Set("Random-Csv-Filename", file.Name())
		http.ServeFile(res, req, "content/"+file.Name())
	})
	http.Handle("/", http.FileServer(http.Dir("content")))
	log.Printf("Serving directory %s at :%s", "content", port)
	return http.ListenAndServe(":"+port, nil)
}