Accessing a Google Sheet with service account credentials from the download JSON.

main.go

package main

import (
	"context"
	"io/ioutil"
	"log"

	"golang.org/x/oauth2/google"
	"google.golang.org/api/sheets/v4"
)

func main() {
	b, err := ioutil.ReadFile("creds.json")
	if err != nil {
		log.Fatalf("Unable to read client secret file: %v", err)
	}

	cfg, err := google.JWTConfigFromJSON(b, sheets.SpreadsheetsScope)
	if err != nil {
		log.Fatalf("while getting config: %v", err)
	}

	client := cfg.Client(context.Background())

	cl, err := sheets.New(client)
	if err != nil {
		log.Fatalf("while creating sheets service: %v", err)
	}
	spreadsheetID := "SOMESPREADSHEETID"
	readRange := "Sheet1!A1:B2"

	rsp, err := cl.Spreadsheets.Values.Get(spreadsheetID, readRange).Do()
	if err != nil {
		log.Fatalf("while getting sheet values: %v", err)
	}

	if len(rsp.Values) == 0 {
		log.Fatalln("0 rows returned")
	}

	for _, row := range rsp.Values {
		log.Printf("%s, %s\n", row[0], row[1])
	}

	log.Printf("%+v", rsp)
}