Pino Logging

Pino is the fastest Node.js JSON logger. Katman's loggingHooks plugs it into the lifecycle hooks system so every request, response, and error is logged automatically.

Setup

import { katman } from "katman"
import pino from "pino"
import { loggingHooks } from "katman/pino"

const k = katman({
  context: (req) => ({ db: getDB() }),
  hooks: loggingHooks({ logger: pino() }),
})

That's it. Every request flowing through your API is now logged.

What gets logged

When a request is received:

{ "level": 30, "path": "users/list", "hasInput": true, "msg": "request received" }

When a response is sent:

{ "level": 30, "path": "users/list", "durationMs": 0.42, "msg": "response sent" }

When an error occurs:

{ "level": 50, "path": "users/create", "error": "CONFLICT", "msg": "request error" }

The durationMs field measures how long the procedure took, rounded to two decimal places.

Options

import { loggingHooks } from "katman/pino"

loggingHooks({
  logger: pino(),
  logRequests: true,   // log "request received" (default: true)
  logResponses: true,  // log "response sent" (default: true)
})

Set logRequests: false to skip the "request received" messages and only log responses and errors. This is useful in high-traffic production environments where you want to reduce log volume.

Errors are always logged regardless of these settings.

Using any logger

The logger option accepts any object that implements this interface:

interface Logger {
  child(bindings: Record<string, unknown>): Logger
  info(obj: Record<string, unknown>, msg?: string): void
  error(obj: Record<string, unknown>, msg?: string): void
  warn(obj: Record<string, unknown>, msg?: string): void
  debug(obj: Record<string, unknown>, msg?: string): void
}

This means you're not locked into Pino. Any logger with compatible methods works — winston with a wrapper, consola, or even a custom logger.

Combining with other hooks

loggingHooks returns a plain hooks object. You can combine it with other hooks by spreading:

import { loggingHooks } from "katman/pino"

const k = katman({
  context: (req) => ({}),
  hooks: {
    ...loggingHooks({ logger: pino() }),
    "serve:start": ({ url }) => {
      console.log(`Server ready at ${url}`)
    },
  },
})

What's next?

• OpenTelemetry — distributed tracing for each procedure call
• Rate Limiting — protect your API from abuse
• Server — lifecycle hooks and serve() options