logging.js

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import Pino from 'pino';
import PinoHttp from 'pino-http';

/**
 * Set project Id for log correlation in request-based logger
 * @param {string} projectId - Google Cloud Platform Project Id
 */
let project;
export const initLogCorrelation = (projectId) => {
  project = projectId;
};

/**
 * Create a custom formatter to set the "severity" property in the JSON payload
 * to the log level to be automatically parsed
 * https://github.com/winstonjs/winston#creating-custom-formats
 * https://cloud.google.com/run/docs/logging#special-fields
 * https://getpino.io/#/docs/api?id=formatters-object
 */
const formatters = {
  level(label) {
    return { severity: label };
  },
};

/**
 * Initialize pino logger
 */
export const logger = Pino({
  formatters,
  // Set log message property name to "message" for automatic parsing
  messageKey: 'message',
});

/**
 * Create request-based logger with trace ID field for logging correlation
 * For more info, see https://cloud.google.com/run/docs/logging#correlate-logs
 */
export const pinoHttp = PinoHttp({
  logger,
  reqCustomProps: function (req) {
    const traceHeader = req.header('X-Cloud-Trace-Context');
    let trace;
    if (traceHeader) {
      const [traceId] = traceHeader.split('/');
      trace = `projects/${project}/traces/${traceId}`;
    }
    return {
      'logging.googleapis.com/trace': trace,
    };
  },
});