Add logging with Winston

lib/logging/logger.ts

@@ -0,0 +1,36 @@
+import winston from "winston";
+
+const logger = winston.createLogger({
+  level: "info",
+  format: winston.format.json(),
+  defaultMeta: { service: "user-service" },
+  transports: [
+    //
+    // - Write all logs with importance level of `error` or higher to `error.log`
+    //   (i.e., error, fatal, but not other levels)
+    //
+    new winston.transports.File({ filename: "error.log", level: "error" }),
+    //
+    // - Write all logs with importance level of `info` or higher to `combined.log`
+    //   (i.e., fatal, error, warn, and info, but not trace)
+    //
+    new winston.transports.File({ filename: "combined.log" }),
+  ],
+});
+
+//
+// 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(),
+    }),
+  );
+  logger.configure({
+    level: "debug",
+  });
+}
+
+export default logger;