From c21da594abe4f14fdf812d3e170bf742c292293f Mon Sep 17 00:00:00 2001
From: Jyrki Ahpola <jyrki.ahpola@futurice.com>
Date: Mon, 4 Sep 2023 10:16:28 +0300
Subject: [PATCH] Structured logging for GCP

---
 src/gcpLogging.ts | 117 ++++++++++++++++++++++++++++++++++++++++++++++
 src/index.ts      |  15 ++----
 2 files changed, 120 insertions(+), 12 deletions(-)
 create mode 100644 src/gcpLogging.ts

diff --git a/src/gcpLogging.ts b/src/gcpLogging.ts
new file mode 100644
index 00000000..34501d17
--- /dev/null
+++ b/src/gcpLogging.ts
@@ -0,0 +1,117 @@
+import pino from "pino";
+
+/**
+ * If https://github.com/googleapis/nodejs-logging/issues/875 is solved
+ * satisfactorily, this module can be simplified or removed.
+ *
+ * More context in
+ * https://github.com/tvv-lippu-ja-maksujarjestelma-oy/waltti-apc/issues/344 .
+ */
+
+/**
+ * Copied from
+ * https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry#logseverity
+ * on 2023-08-31.
+ *
+ * DEFAULT (0) The log entry has no assigned severity level.
+ * DEBUG (100) Debug or trace information.
+ * INFO (200) Routine information, such as ongoing status or performance.
+ * NOTICE (300) Normal but significant events, such as start up, shut down, or a configuration change.
+ * WARNING (400) Warning events might cause problems.
+ * ERROR (500) Error events are likely to cause problems.
+ * CRITICAL (600) Critical events cause more severe problems or outages.
+ * ALERT (700) A person must take an action immediately.
+ * EMERGENCY (800) One or more systems are unusable.
+ */
+export type GcpLogSeverity =
+  | "DEFAULT"
+  | "DEBUG"
+  | "INFO"
+  | "NOTICE"
+  | "WARNING"
+  | "ERROR"
+  | "CRITICAL"
+  | "ALERT"
+  | "EMERGENCY";
+
+export const changePinoLevelToGcpLogSeverity = (
+  level: pino.LevelWithSilent,
+): GcpLogSeverity => {
+  switch (level) {
+    case "trace":
+      return "DEBUG";
+    case "debug":
+      return "DEBUG";
+    case "info":
+      return "INFO";
+    case "warn":
+      return "WARNING";
+    case "error":
+      return "ERROR";
+    case "fatal":
+      return "CRITICAL";
+    case "silent":
+      return "DEFAULT";
+    default:
+      return "DEFAULT";
+  }
+};
+
+/**
+ * Modified from
+ * https://github.com/googleapis/nodejs-logging/issues/875#issuecomment-690556487
+ * on 2023-09-02.
+ *
+ * Use
+ * https://cloud.google.com/error-reporting/docs/formatting-error-messages#json_representation
+ * as reference.
+ */
+export const createLogger = <Options extends pino.LoggerOptions>(
+  options: Options & { name: string },
+  stream?: pino.DestinationStream,
+): pino.Logger<Options> =>
+  pino(
+    {
+      timestamp: pino.stdTimeFunctions.isoTime,
+      redact: { paths: ["pid"], remove: true },
+      // As logger is started before config is created, read the level from env.
+      level: options.level ?? process.env["PINO_LOG_LEVEL"] ?? "info",
+      // Specific to GCP.
+      base: { serviceContext: { service: options.name } },
+      // Specific to GCP.
+      messageKey: "message",
+      // Specific to GCP.
+      formatters: {
+        level(label: pino.Level): object {
+          // `@type` property tells Error Reporting to track even if there is no
+          // `stack_trace`
+          const typeProperty =
+            label === "error" || label === "fatal"
+              ? {
+                  "@type":
+                    "type.googleapis.com/google.devtools.clouderrorreporting.v1beta1.ReportedErrorEvent",
+                }
+              : {};
+          return {
+            level: label,
+            severity: changePinoLevelToGcpLogSeverity(label),
+            ...typeProperty,
+          };
+        },
+        log(
+          object: Record<string, unknown> & { err?: Error },
+        ): Record<string, unknown> {
+          const stackTrace = object.err?.stack;
+          const stackProperty = stackTrace ? { stack_trace: stackTrace } : {};
+          return {
+            ...object,
+            ...stackProperty,
+          };
+        },
+      },
+      // options must include name according to our type signature so no need to
+      // add it separately.
+      ...options,
+    },
+    stream ?? pino.destination({ sync: true }),
+  );
diff --git a/src/index.ts b/src/index.ts
index 625dce6a..dce2bd80 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -9,6 +9,7 @@ import {
   createPulsarConsumer,
 } from "./pulsar";
 import transformUnknownToError from "./util";
+import { createLogger } from "./gcpLogging";
 
 /**
  * Exit gracefully.
@@ -109,18 +110,8 @@ const exitGracefully = async (
   /* eslint-enable @typescript-eslint/no-floating-promises */
   const serviceName = "waltti-apc-journey-matcher";
   try {
-    const logger = pino(
-      {
-        name: serviceName,
-        timestamp: pino.stdTimeFunctions.isoTime,
-        redact: { paths: ["pid"], remove: true },
-        // As logger is started before config is created, read the level from
-        // env.
-        level: process.env["PINO_LOG_LEVEL"] ?? "info",
-      },
-      pino.destination({ sync: true })
-    );
-
+    const logger = createLogger({ name: serviceName });
+    
     let setHealthOk: (isOk: boolean) => void;
     let closeHealthCheckServer: () => Promise<void>;
     let client: Pulsar.Client;