func NewBolt(dbfile, bucket string) *Bolt {
	db, err := bolt.Open(dbfile, 0644, nil)
	if err != nil {
		log.Panicln(err)
	}
	return &Bolt{db, dbfile, bucket}
}
NewBolt opens boltdb to initialize Bolt.
The path of the db file that stores event data is specified in the configuration file(yaml).
package main
import (
	"fmt"
	"log"
	"github.com/boltdb/bolt"
)
type Bolt struct {
	Db     *bolt.DB
	Dbfile string
	Bucket string
}