Chore: again, improve k8s error logging

src/utils/logger.js

@@ -18,23 +18,16 @@ function combineMessageAndSplat() {
 }
 
 function messageFormatter(logInfo) {
-  if (logInfo.label) {
-    if (logInfo.stack) {
-      return `[${logInfo.timestamp}] ${logInfo.level}: <${logInfo.label}> ${logInfo.stack}`;
-    }
-    return `[${logInfo.timestamp}] ${logInfo.level}: <${logInfo.label}> ${logInfo.message}`;
-  }
-
-  if (logInfo.stack) {
-    return `[${logInfo.timestamp}] ${logInfo.level}: ${logInfo.stack}`;
-  }
-  return `[${logInfo.timestamp}] ${logInfo.level}: ${logInfo.message}`;
+  const label = logInfo.label ? `<${logInfo.label}> ` : "";
+  // e.g. fetch errors say nothing useful without the cause
+  const cause = logInfo.cause ? `\ncaused by: ${logInfo.cause.stack ?? logInfo.cause}` : "";
+  return `[${logInfo.timestamp}] ${logInfo.level}: ${label}${logInfo.stack || logInfo.message}${cause}`;
 }
 
 function getConsoleLogger() {
   return new winston.transports.Console({
     format: winston.format.combine(
-      winston.format.errors({ stack: true }),
+      winston.format.errors({ stack: true, cause: true }),
       combineMessageAndSplat(),
       winston.format.timestamp(),
       winston.format.colorize(),
@@ -51,7 +44,7 @@ function getFileLogger() {
 
   return new winston.transports.File({
     format: winston.format.combine(
-      winston.format.errors({ stack: true }),
+      winston.format.errors({ stack: true, cause: true }),
       combineMessageAndSplat(),
       winston.format.timestamp(),
       winston.format.printf(messageFormatter),

src/utils/logger.test.js

@@ -170,6 +170,16 @@ describe("utils/logger", () => {
     });
     expect(plainMsg).toBe("[t] info: hello");
 
+    const causeMsg = formatter({
+      timestamp: "t",
+      level: "error",
+      label: "x",
+      stack: "STACK",
+      message: "fetch failed",
+      cause: { stack: "CAUSE STACK" },
+    });
+    expect(causeMsg).toBe("[t] error: <x> STACK\ncaused by: CAUSE STACK");
+
     const out = splat.transform(
       {
         message: "Hello %s",