feat(*): Add initialiseLogger method

logger.js

@@ -0,0 +1,78 @@
+module.exports = {
+  initialiseLogger: function (config, winston, Elasticsearch) {
+    const { format } = winston;
+    const { combine, timestamp } = format;
+
+    let env = 'dev';
+    if (process.env.NODE_ENV === 'production') {
+      env = 'prod';
+    }
+
+    // Custom format function that will look for an error object and log out the stack and if
+    // its not production, the error itself
+    const myFormat = format.printf((info) => {
+      const { timestamp: tmsmp, level, message, error, ...rest } = info;
+      let log = `${tmsmp} - ${level}:\t${message}`;
+      // Only if there is an error
+      if ( error ) {
+        if ( error.stack) log = `${log}\n${error.stack}`;
+        if (process.env.NODE_ENV !== 'production') log = `${log}\n${JSON.stringify(error, null, 2)}`;
+      }
+      // Check if rest is object
+      if ( !( Object.keys(rest).length === 0 && rest.constructor === Object ) ) {
+        log = `${log}\n${JSON.stringify(rest, null, 2)}`;
+      }
+      return log;
+    });
+
+    const esTransportOpts = {
+      level: 'info',
+      indexPrefix: 'logs_mupbot',
+      clientOpts: {
+          host: config.elasticsearch.elasticsearch_address,
+          log: 'info'
+      },
+      transformer: logData => {
+          return {
+            timestamp: new Date().toISOString(),
+            severity: logData.level,
+            message: logData.message,
+            meta: {
+              app: 'mupbot',
+              env: env,
+              stack: logData.meta.stack
+            }
+          }
+      }
+    };
+
+    const logger = winston.createLogger({
+      level: 'info',
+      format: combine(
+        winston.format.errors({ stack: true }), // <-- use errors format
+        winston.format.timestamp(),
+        winston.format.prettyPrint(),
+        myFormat,
+        winston.format.json()
+      ),
+      defaultMeta: { service: 'user-service' },
+      transports: [
+        new winston.transports.File({ filename: 'error.log', level: 'error' }),
+        new winston.transports.File({ filename: 'combined.log' }),
+        new Elasticsearch(esTransportOpts)
+      ],
+    });
+
+    //
+    // If we're not in production then log to the `console` with the format:
+    // `${info.level}: ${info.message} JSON.stringify({ ...rest }) `
+    //
+    //if (process.env.NODE_ENV !== 'production') {
+      logger.add(new winston.transports.Console({
+        format: winston.format.simple(),
+      }));
+    //}
+
+    return logger;
+  },
+};