Help with sending logs to slack on graceful shutdown

[nenadfilipovic]

Can I get some guidelines how to handle this situation. I need to report errors to my Slack channel and results are very inconsistent. Startup logs works fine but when I hit ctrl+c I dont get any output when using custom transport even if I just console.log obj in code example below. For graceful shutdown I am using https://www.npmjs.com/package/http-graceful-shutdown and transport is simple

export default async function (opts) {
  return build(async function (source) {
    for await (let obj of source) {
      await sendSlackMessage with @slack/webhooks api
    }
  })
}

What I need to do to be able to catch logs before my servers exits? Thanks.

[mcollina]

It's very hard to help you given that we cannot run the code. Could you create an example that is just calling an http endpoint to simulate slack?

[nenadfilipovic]

Ok. lets try

Transport

import build from 'pino-abstract-transport';

export default async function (options) {
  return build(async (source) => {
    for await (let obj of source) {
      console.log(obj);
    }
  });
}

Logger

export const logger = pino(
  pino.transport({
    target: './slackTransport.js',
  }),
);

Server

import http from 'http';
import express from "express";
import { logger } from './logger.js';
import gracefulShutdown from 'http-graceful-shutdown'

const app = express();

const server = http.createServer(app);

server.listen(3002, () => {
    console.log('start');
})

const preShutdown = async () => {
  logger.info(`Stopping server...`);
};

const shutdown = gracefulShutdown(server, {
  preShutdown,
  forceExit: false,
  finally: () => {
    logger.info(`Server stopped!`);
  },
});

Graceful shutdown package will handle SIGINT, SIGTERM signals. Without transport pino will log after ctrl+c and with transport it will exit silently.

[nenadfilipovic]

@mcollina any chance to look at this?

[mcollina]

Unfortunately not yet, it's in the queue after Fastify v4.

things to verify, in this order:

1. never use console.log in workers. It does not work the way you think.
2. http-graceful-shutdown might be incompatible with pino transports and a change here or there might be needed.

[nenadfilipovic]

Thanks, I was banging my head so much with inconsistencies with console.log.

[Fdawgs]

@nenadfilipovic Did you manage to resolve this?