Node-bunyan: Empty "err" if Error object is not passed as root

[mouhong]

How to reproduce:

Environment:
node 5.7.0
bunyan 1.7.1

test.js:

var log = bunyan.createLogger({ name: 'app' });
log.error({ err: new Error('not work'), other_field: 123 }, 'Something went wrong...');

Then in shell:

node test.js | bunyan

Output:

[2016-03-08T11:27:11.291Z] ERROR: Something went wrong... (err={}, other_field:123)

If I pass Error object as root, like this:

log.error(new Error('not work'), 'Something went wrong...');

The output will be (expected):

[2016-03-08T11:34:23.388Z] ERROR: Something went wrong...
    Error: not work
        at Object.<anonymous> (/.../test.js:9:14)
        at Module._compile (module.js:413:34)
        at Object.Module._extensions..js (module.js:422:10)
        at Module.load (module.js:357:32)
        at Function.Module._load (module.js:314:12)
        at Function.Module.runMain (module.js:447:10)
        at startup (node.js:141:18)
        at node.js:933:3

In both cases I passed in the Error object. But in the former case, it doesn't print the error stack trace while in the latter case it prints the error stack trace. I think the behaviors should be consistent, that is, both print the error stack trace.

[Khez]

When you pass an error as the "root", you gain the standard error logger by default.

Try to pass the standard serializers during createLogger. Should fix your issue

var log = bunyan.createLogger({
    name: 'app',
    serializers: bunyan.stdSerializers
});

I do agree the behaviour might feel a little inconsistent though...

[mouhong]

@Khez your solution works. Thanks!

[springuper]

@Khez this workaround does not fix my problem, because I have to set serializers to other values:

serializers: {
  error: bunyan.stdSerializers.err,
  request: reqSerializer,
  response: bunyan.stdSerializers.res
}

any suggestions?

[phillipj]

Passing serializers as suggested worked for me, thanks 👍

Any thoughts on documenting the need to do this or what needs in bunyan core to handle this w/o explicit serializers? Reading the current README gives an impression this is handled out of the box -- spent a good amount of time digging into this, until finding this issue with a working fix :)

[rickyblaha]

I just ran into this too, and the suggested workarounds above didn't fix it. I'm using node 6.9.1 in a docker container with pm2 running a process, and bunyan 1.8.5. Logging err directly works when running the app locally, but when in the container environment it's logged as an empty object.

This solved it for me -- instead of logger.error({err, other: 123}, 'foo'), use the stack property: logger.error({err: err.stack, other: 123}, 'foo'). Then the full stack trace starting with the actual error message message appears in the bunyan logs.

[trentm]

Sorry for the delay in responding. #398 and #7 are basically the same issue. The README example showing logging an error via log.info({err: err, ...}, 'foo'); didn't at all make it clear that that requires having an err serializer.

I tried to improve the README in https://github.com/trentm/node-bunyan/commit/e540a76424f56837c53e58b06298ffefbcbf92d9