Add support for Vercel log limit

.changeset/rare-crews-end.md

@@ -0,0 +1,5 @@
+---
+"@saleor/apps-logger": minor
+---
+
+If Vercel runtime transport log is exceeding Vercel log limit (4kb) error to Sentry will be logged as it won't be visible in log drain.

packages/logger/package.json

@@ -17,7 +17,9 @@
     "@sentry/nextjs": "../../node_modules/@sentry/nextjs",
     "eslint-config-saleor": "workspace:*",
     "vite": "5.3.3",
-    "vitest": "1.6.0"
+    "vitest": "1.6.0",
+    "modern-errors": "7.0.1",
+    "modern-errors-serialize": "6.0.0"
   },
   "exports": {
     ".": {

packages/logger/src/errors.ts

@@ -0,0 +1,8 @@
+import ModernError from "modern-errors";
+import modernErrorsSerialize from "modern-errors-serialize";
+
+export const BaseError = ModernError.subclass("BaseError", {
+  plugins: [modernErrorsSerialize],
+});
+
+export const UnknownError = BaseError.subclass("UnknownError");

packages/logger/src/logger-vercel-runtime-transport.ts

@@ -2,8 +2,17 @@ import { trace } from "@opentelemetry/api";
 import * as Sentry from "@sentry/nextjs";
 import { ILogObj, Logger } from "tslog";
 
+import { BaseError, UnknownError } from "./errors";
 import { LoggerContext } from "./logger-context";
 
+const VercelMaximumLogSizeExceededError = BaseError.subclass("VercelMaximumLogSizeExceededError");
+
+function isLogExceedingVercelLimit(inputString: string): boolean {
+  const byteLength = new TextEncoder().encode(inputString).length;
+
+  return byteLength > 4096; // Vercel serverless function log limit - 4KB
+}
+
 export const attachLoggerVercelRuntimeTransport = (
   logger: Logger<ILogObj>,
   appVersion: string,
@@ -39,6 +48,17 @@ export const attachLoggerVercelRuntimeTransport = (
         },
       });
 
+      if (isLogExceedingVercelLimit(stringifiedMessage)) {
+        Sentry.captureException(
+          new VercelMaximumLogSizeExceededError("Log message is exceeding Vercel limit", {
+            props: {
+              logName: log._meta.name,
+              logMessage: bodyMessage,
+            },
+          }),
+        );
+      }
+
       // Prints Vercel log in proper level https://vercel.com/docs/observability/runtime-logs#level
       if (_meta.logLevelName === "ERROR") {
         console.error(stringifiedMessage);
@@ -53,7 +73,7 @@ export const attachLoggerVercelRuntimeTransport = (
       console.log(stringifiedMessage);
     } catch (error) {
       Sentry.captureException(
-        new Error("Error during attaching Vercel transport", {
+        new UnknownError("Error during attaching Vercel transport", {
           cause: error,
         }),
       );