feat: Replace Bunyan logger with Pino

cloudrun-malware-scanner/logger.js

@@ -13,24 +13,77 @@
 // limitations under the License.
 
 /**
- * Create a Bunyan Logger using structured logging to stdout.
+ * Create a Pino Logger using structured logging to stdout.
  */
 
+const {pino} = require('pino');
 const process = require('node:process');
-const bunyan = require('bunyan');
-const {LoggingBunyan} = require('@google-cloud/logging-bunyan');
-const pkgJson = require('./package.json');
-
-// Create logging client.
-const loggingBunyan = new LoggingBunyan({
-  redirectToStdout: true,
-  projectId: process.env.PROJECT_ID,
-  logName: 'malware-scanner',
-  useMessageField: false,
-});
-
-exports.logger = bunyan.createLogger({
-  name: pkgJson.name,
-  streams: [loggingBunyan.stream('info')],
-  serializers: bunyan.stdSerializers,
-});
+
+// https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry#logseverity
+const PinoLevelToSeverityLookup = new Map([
+  ['trace', 'DEBUG'],
+  ['debug', 'DEBUG'],
+  ['info', 'INFO'],
+  ['warn', 'WARNING'],
+  ['error', 'ERROR'],
+  ['fatal', 'CRITICAL'],
+]);
+
+/**
+ * Return a pino log level based on environment variables.
+ *
+ * @return {string}
+ */
+function getLogLevel() {
+  const envLogLevel = process.env.LOG_LEVEL
+    ? process.env.LOG_LEVEL.toLowerCase()
+    : null;
+
+  if (envLogLevel && PinoLevelToSeverityLookup.get(envLogLevel)) {
+    return envLogLevel;
+  } else if (process.env.NODE_ENV?.toLowerCase() === 'test') {
+    return 'fatal';
+  } else {
+    return 'info';
+  }
+}
+
+/**
+ * Convert pino log level to Google severity
+ * @param {string} label
+ * @param {number} number
+ * @returns {Object}
+ */
+function pinoLevelToStackdriver(label, number) {
+  return {
+    severity: PinoLevelToSeverityLookup.get(label) || 'INFO',
+    level: number,
+  };
+}
+
+/**
+ * Create a JSON fragment string containing the timestamp in Stackdriver format:
+ * <pre>
+ * "timestamp": {
+ *   "seconds": nnnnn,
+ *   "nanos": nnnnn
+ * }`
+ * </pre>
+ * @returns {string}
+ */
+function getStackdriverTimestamp() {
+  const millis = Date.now();
+  return `,"timestamp":{"seconds":${Math.floor(millis / 1000)},"nanos": ${millis % 1000}000000}`;
+}
+
+/** @type {pino.LoggerOptions} */
+const pinoConfig = {
+  level: getLogLevel(),
+  messageKey: 'message',
+  formatters: {
+    level: pinoLevelToStackdriver,
+  },
+  timestamp: getStackdriverTimestamp,
+};
+
+exports.logger = pino(pinoConfig);