Pino-pretty doesn't work if timestamp is changed

[augusto-dmh]

I was trying to understand why, even with all due properties set and the script ok for running logs formatted with pino-pretty, why the logs were being this way - unformatted:

{"level":"ERROR"",timestamp":"2024-03-12T12:47:54.530Z","status":401,"message":"'authorization' header is required."

After checking if i was doing all the config stuff correctly, i tested taking off all configuration i've put on my logger, then i noticed that with timestamps changed like below, the prettier wouldn't work:

const logger = pino(
  {
    base: undefined,
    level: process.env.LOG_LEVEL,
    redact: {
      paths: ["email", "password"],
      censor: "[RESTRICTED]",
    },
    timestamp: () => `",timestamp":"${new Date(Date.now()).toISOString()}"`,
    formatters: {
      level: (label) => ({ level: label.toUpperCase() }),
    },
  },
  transport,
);

After removing the line with customized timestamp, the log was as should be:

[09:45:33.188] �[31mERROR�[39m:
status: 401
message: "'authorization' header is required."

So the pino-pretty package apparently doesnt work with a customized timestamp.

[mcollina]

Thanks for reporting! Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[augusto-dmh]

You're welcome! Well, at the moment i haven't studied yet about unit tests, but sooner or later i will and i'll come back here!

[mahmoodhamdi]

This isn't actually a bug — when you rename the timestamp key from the default time to timestamp, you need to tell pino-pretty about it using the timestampKey option:

const transport = pino.transport({
  target: 'pino-pretty',
  options: {
    timestampKey: 'timestamp'  // match your custom key name
  }
})

Or via CLI:

node app.js | pino-pretty --timestampKey timestamp

pino-pretty defaults to looking for time as the timestamp key (which is pino's default). When you use a custom timestamp function in pino that changes the key name, pino-pretty doesn't know where to find the timestamp unless you configure it.

This is documented in the README under the timestampKey option.

[segevfiner]

I think this is more about how to get pino-pretty to work when the timestamp format changes rather then the property name/key.

[mahmoodhamdi]

Good point, you're right — the issue is actually about both the key name and the timestamp format.

When using a custom timestamp function like:

timestamp: () => \`,"timestamp":"\${new Date(Date.now()).toISOString()}"\`

Two things change:

1. The key name changes from time to timestamp (which timestampKey fixes)
2. The value changes from epoch ms (1710240000000) to an ISO string ("2024-03-12T12:47:54.530Z")

pino-pretty can handle ISO strings fine as long as it knows where to find them. But the actual formatting issue the OP reported (logs appearing raw/unformatted) was because pino-pretty could not locate the timestamp field at all — it was looking for time but the data had timestamp.

So timestampKey: "timestamp" does solve the OP's specific problem. But if someone also wants to control how pino-pretty renders the timestamp (regardless of the input format), they can use the customPrettifiers option:

const transport = pino.transport({
  target: "pino-pretty",
  options: {
    timestampKey: "timestamp",
    customPrettifiers: {
      time(value) {
        return new Date(value).toLocaleString()
      }
    }
  }
})

Thanks for the clarification!