Fastify GCP Stackdriver logging agent compatible pino logger

logger.ts

import * as P from 'pino'
import {FastifyReply, FastifyRequest} from 'fastify'

const enum PINO_LEVELS {
  trace = 10,
  debug = 20,
  info = 30,
  warn = 40,
  error = 50,
  fatal = 60,
}

function pinoLevelToStackdriverSeverity(level: PINO_LEVELS) {
  if (level === PINO_LEVELS.trace || level === PINO_LEVELS.debug) {
    return 'debug'
  }
  if (level === PINO_LEVELS.info) {
    return 'info'
  }
  if (level === PINO_LEVELS.warn) {
    return 'warning'
  }
  if (level === PINO_LEVELS.error) {
    return 'error'
  }
  if (level >= PINO_LEVELS.fatal) {
    return 'critical'
  }
  return 'default'
}

function truncateToDecimalPlace(value: number, decimalPlace: number) {
  return (
    Math.trunc(value * Math.pow(10, decimalPlace)) / Math.pow(10, decimalPlace)
  )
}

interface LogEntryHTTPRequest {
  requestMethod?: string
  requestUrl?: string
  requestSize?: string
  status?: number
  responseSize?: string
  userAgent?: string
  remoteIp?: string
  serverIp?: string
  referer?: string
  latency?: string
  cacheLookup?: boolean
  cacheHit?: boolean
  cacheValidatedWithOriginServer?: boolean
  cacheFillBytes?: string
  protocol?: string
}

interface LogObject {
  req?: FastifyRequest
  res?: FastifyReply
  httpRequest?: LogEntryHTTPRequest
  requestId?: string
}

const logger = P({
  messageKey: 'message',
  timestamp: false,
  base: undefined,
  
  formatters: {
    level(_label, number) {
      return {
        severity: pinoLevelToStackdriverSeverity(number),
      }
    },
    log(object: LogObject) {
      // Setuping the Stackdriver httpRequest property on the log entry
      if (object.req) {
        object.httpRequest = {
          ...(object.httpRequest ?? {},
          {
            requestMethod: object.req.method,
            requestUrl: object.req.url,
            userAgent: object.req.headers['user-agent'],
            remoteIp: object.req.ip,
            protocol: object.req.protocol,
          })
        }
      }
      if (object.res) {
        object.httpRequest = {
          ...(object.httpRequest ?? {},
          {
            requestMethod: object.res.request.method,
            requestUrl: object.res.request.url,
            status: object.res.statusCode,
            userAgent: object.res.request.headers['user-agent'],
            latency: `${truncateToDecimalPlace(object.res.getResponseTime() / 1000, 9)}s`,
            remoteIp: object.res.request.ip,
            protocol: object.res.request.protocol,
          }),
        }
      }
      return object
    }
  },
  serializers: {
    // Nullifying the standard Fastify Request/Response serializer for better stackdriver support
    req(request: FastifyRequest) { return undefined },
    res(reply: FastifyReply) { return undefined },
    responseTime: function(value) { return undefined }
  }
})

export default logger

Thank you for posting this! Was driving crazy trying to find an easy way to get pino to behave with stackdriver.

Thank you for posting this! Was driving crazy trying to find an easy way to get pino to behave with stackdriver.

My pleasure, it is definately tricky and a bit of a hack job to make it work good 😓