Create database package (refactoring)

database/database.go

@@ -0,0 +1,25 @@
+// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package database
+
+import (
+	"database/sql"
+
+	// Postgresql driver import
+	_ "github.com/lib/pq"
+)
+
+// NewConnectionPool configures the database connection pool.
+func NewConnectionPool(dsn string, minConnections, maxConnections int) (*sql.DB, error) {
+	db, err := sql.Open("postgres", dsn)
+	if err != nil {
+		return nil, err
+	}
+
+	db.SetMaxOpenConns(maxConnections)
+	db.SetMaxIdleConns(minConnections)
+
+	return db, nil
+}