100-go-mistakes/2-code-project-organization/3-init-functions/db/main.go

package main

import (
	"database/sql"
	"log"
	"os"
)

var db *sql.DB

func init() {
	dataSourceName := os.Getenv("MYSQL_DATA_SOURCE_NAME")
	d, err := sql.Open("mysql", dataSourceName)
	if err != nil {
		log.Panic(err)
	}
	err = d.Ping()
	if err != nil {
		log.Panic(err)
	}
	db = d
}