rootCertPool := x509.NewCertPool()
pem, err := os.ReadFile("${ca_path}")
if err != nil {
	log.Fatal(err)
}
if ok := rootCertPool.AppendCertsFromPEM(pem); !ok {
	log.Fatal("Failed to append PEM.")
}
mysql.RegisterTLSConfig("tidb", &tls.Config{
	RootCAs:    rootCertPool,
	MinVersion: tls.VersionTLS12,
	ServerName: "${host}",
})

db, err := sql.Open("mysql", "${username}:${password}@tcp(${host}:${port})/${database}?tls=tidb")