Convert backend code to ES modules

Bundling code now with Rollup for its flat bundling and tree shaking
support. Front end code still goes through Webpack for browser support.

lib/logger.js

@@ -18,10 +18,10 @@
  */
 "use strict";
 
-const fs = require("fs");
-const os = require("os");
+import fs from "fs";
+import os from "os";
 
-const config = require("./config");
+import * as config from "./config";
 
 const REOPEN_EVERY = 60000;
 
@@ -90,7 +90,7 @@ function reopen() {
     setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
 }
 
-function init(service, version) {
+export function init(service, version) {
   defaultMeta.hostname = os.hostname();
   defaultMeta.pid = process.pid;
   defaultMeta.name = `genieacs-${service}`;
@@ -129,12 +129,12 @@ function init(service, version) {
     setTimeout(reopen, REOPEN_EVERY - (Date.now() % REOPEN_EVERY)).unref();
 }
 
-function close() {
+export function close() {
   accessLogStream.end();
   logStream.end();
 }
 
-function flatten(details) {
+export function flatten(details) {
   if (details.sessionContext) {
     details.deviceId = details.sessionContext.deviceId;
     details.remoteAddress =
@@ -265,22 +265,22 @@ function log(details) {
   }
 }
 
-function info(details) {
+export function info(details) {
   details.severity = "info";
   log(details);
 }
 
-function warn(details) {
+export function warn(details) {
   details.severity = "warn";
   log(details);
 }
 
-function error(details) {
+export function error(details) {
   details.severity = "error";
   log(details);
 }
 
-function accessLog(details) {
+export function accessLog(details) {
   details.timestamp = new Date().toISOString();
   if (ACCESS_LOG_FORMAT === "json") {
     Object.assign(details, defaultMeta);
@@ -290,27 +290,17 @@ function accessLog(details) {
   }
 }
 
-function accessInfo(details) {
+export function accessInfo(details) {
   details.severity = "info";
   accessLog(details);
 }
 
-function accessWarn(details) {
+export function accessWarn(details) {
   details.severity = "warn";
   accessLog(details);
 }
 
-function accessError(details) {
+export function accessError(details) {
   details.severity = "error";
   accessLog(details);
 }
-
-exports.init = init;
-exports.close = close;
-exports.flatten = flatten;
-exports.info = info;
-exports.warn = warn;
-exports.error = error;
-exports.accessInfo = accessInfo;
-exports.accessWarn = accessWarn;
-exports.accessError = accessError;