Boilerplates, base config, folder structure, utils, etc.

utils/logger.js

@@ -0,0 +1,59 @@
+const path = require("path");
+
+const { createLogger, transports, config, format } = require("winston");
+const { combine, label, timestamp, printf } = format;
+
+const typedefs = require("../typedefs");
+
+const getLabel = (callingModule) => {
+  const parts = callingModule.filename.split(path.sep);
+  return path.join(parts[parts.length - 2], parts.pop());
+};
+
+const logMetaReplacer = (key, value) => {
+  if (key === "error") {
+    return value.name + ": " + value.message;
+  }
+  return value;
+}
+
+const metaFormat = (meta) => {
+  if (Object.keys(meta).length > 0)
+    return "\n" + JSON.stringify(meta, logMetaReplacer) + "\n";
+  return "\n";
+}
+
+const logFormat = printf(({ level, message, label, timestamp, ...meta }) => {
+  if (meta.error) {
+    for (const key in meta.error) {
+      if (typeof key !== "symbol" && key !== "message" && key !== "name") {
+        delete meta.error[key]
+      }
+    }
+  }
+  return `${timestamp} [${label}] ${level}: ${message}${metaFormat(meta)}`;
+});
+
+/**
+ * Creates a curried function, and call it with the module in use to get logs with filename
+ * @param {typedefs.Module} callingModule The module from which the logger is called
+ * @returns {typedefs.Logger} 
+ */
+const logger = (callingModule) => {
+  return createLogger({
+    levels: config.npm.levels,
+    format: combine(
+      label({ label: getLabel(callingModule) }),
+      timestamp({ format: "YYYY-MM-DD HH:mm:ss" }),
+      logFormat,
+    ),
+    transports: [
+      process.env.NODE_ENV !== "production" ?
+        new transports.Console() :
+        new transports.File({ filename: __dirname + "/../logs/common.log" }),
+      new transports.File({ filename: __dirname + "/../logs/error.log", level: "error" }),
+    ]
+  });
+}
+
+module.exports = logger;