separate utilities for logs

lib/log-utils.js

@@ -0,0 +1,37 @@
+const path = require('path')
+const winston = require('winston')
+require('winston-daily-rotate-file')
+
+const createDailyRotateLogFileTransport = () => {
+  const transport =  new (winston.transports.DailyRotateFile)({
+    filename: path.join(__dirname, '..', 'logs', 'app-%DATE%.log'),
+    datePattern: 'YYYY-MM-DD',
+    zippedArchive: false,
+    maxSize: '20m',
+    maxFiles: '14d',
+  })
+
+  return transport
+}
+
+const createTransports = (dev) => {
+  return [
+    dev && new winston.transports.Console(),
+    createDailyRotateLogFileTransport(),
+  ].filter(transport => transport)
+}
+
+const createAppLogger = ({ dev }) => {
+  return winston.createLogger({
+    transports: createTransports(dev),
+    format: winston.format.combine(
+      winston.format.timestamp(),
+      winston.format.json()
+    ),
+  })
+}
+
+module.exports = {
+  createTransports,
+  createAppLogger,
+}