pino-std-serializers

What is pino-std-serializers?

The pino-std-serializers package provides standard serializers for the Pino logging library. These serializers help in formatting various types of JavaScript objects and values into a more structured and readable format for logging purposes. This is particularly useful in applications where consistent log formats are necessary for debugging and monitoring.

What are pino-std-serializers's main functionalities?

req (HTTP request serializer)

Serializes HTTP request objects to log them in a structured format, including method, url, headers, and other relevant information.

const pino = require('pino');
const stdSerializers = require('pino-std-serializers');
const logger = pino({
  serializers: {
    req: stdSerializers.req
  }
});

http.createServer((req, res) => {
  logger.info({req}, 'request received');
  res.end('hello world');
}).listen(3000);

res (HTTP response serializer)

Serializes HTTP response objects to capture and log status code, headers, and other response attributes.

const pino = require('pino');
const stdSerializers = require('pino-std-serializers');
const logger = pino({
  serializers: {
    res: stdSerializers.res
  }
});

http.createServer((req, res) => {
  res.on('finish', () => {
    logger.info({res}, 'response sent');
  });
  res.end('hello world');
}).listen(3000);

err (Error serializer)

Provides a way to serialize error objects, including the message, stack trace, and other properties, which aids in debugging and error tracking.

const pino = require('pino');
const stdSerializers = require('pino-std-serializers');
const logger = pino({
  serializers: {
    err: stdSerializers.err
  }
});

try {
  throw new Error('Something went wrong');
} catch (err) {
  logger.error({err}, 'error occurred');
}

Other packages similar to pino-std-serializers

morgan-json

While not a direct serializer library, morgan-json provides middleware to format HTTP request logs into JSON using Morgan, which can be seen as an alternative approach to logging HTTP requests compared to using pino-std-serializers with Pino.

README

pino-std-serializers  

This module provides a set of standard object serializers for the Pino logger.

Serializers

exports.err(error)

Serializes an Error like object. Returns an object:

{
  type: 'string', // The name of the object's constructor.
  message: 'string', // The supplied error message.
  stack: 'string', // The stack when the error was generated.
  raw: Error  // Non-enumerable, i.e. will not be in the output, original
              // Error object. This is available for subsequent serializers
              // to use.
  [...any additional Enumerable property the original Error had]
}

Any other extra properties, e.g. statusCode, that have been attached to the object will also be present on the serialized object.

If the error object has a cause property, the cause's message and stack will be appended to the top-level message and stack. All other parameters that belong to the error.cause object will be omitted.

Example:

const serializer = require('pino-std-serializers').err;

const innerError = new Error("inner error");
innerError.isInner = true;
const outerError = new Error("outer error", { cause: innerError });
outerError.isInner = false;

const serialized = serializer(outerError);
/* Result:
{
  "type": "Error",
  "message": "outer error: inner error",
  "isInner": false,
  "stack": "Error: outer error
        at <...omitted..>
    caused by: Error: inner error
        at <...omitted..>
}
 */

exports.errWithCause(error)

Serializes an Error like object, including any error.cause. Returns an object:

{
  type: 'string', // The name of the object's constructor.
  message: 'string', // The supplied error message.
  stack: 'string', // The stack when the error was generated.
  cause?: Error, // If the original error had an error.cause, it will be serialized here
  raw: Error  // Non-enumerable, i.e. will not be in the output, original
              // Error object. This is available for subsequent serializers
              // to use.
  [...any additional Enumerable property the original Error had]
}

Any other extra properties, e.g. statusCode, that have been attached to the object will also be present on the serialized object.

Example:

const serializer = require('pino-std-serializers').errWithCause;

const innerError = new Error("inner error");
innerError.isInner = true;
const outerError = new Error("outer error", { cause: innerError });
outerError.isInner = false;

const serialized = serializer(outerError);
/* Result:
{
  "type": "Error",
  "message": "outer error",
  "isInner": false,
  "stack": "Error: outer error
    at <...omitted..>",
  "cause": {
    "type": "Error",
    "message": "inner error",
    "isInner": true,
    "stack": "Error: inner error
      at <...omitted..>"
  },
}
 */

exports.mapHttpResponse(response)

Used internally by Pino for general response logging. Returns an object:

{
  res: {}
}

Where res is the response as serialized by the standard response serializer.

exports.mapHttpRequest(request)

Used internall by Pino for general request logging. Returns an object:

{
  req: {}
}

Where req is the request as serialized by the standard request serializer.

exports.req(request)

The default request serializer. Returns an object:

{
  id: 'string', // Defaults to `undefined`, unless there is an `id` property
                // already attached to the `request` object or to the `request.info`
                // object. Attach a synchronous function
                // to the `request.id` that returns an identifier to have
                // the value filled.
  method: 'string',
  url: 'string', // the request pathname (as per req.url in core HTTP)
  query: 'object', // the request query (as per req.query in express or hapi)
  params: 'object', // the request params (as per req.params in express or hapi)
  headers: Object, // a reference to the `headers` object from the request
                   // (as per req.headers in core HTTP)
  remoteAddress: 'string',
  remotePort: Number,
  raw: Object // Non-enumerable, i.e. will not be in the output, original
              // request object. This is available for subsequent serializers
              // to use. In cases where the `request` input already has
              // a `raw` property this will replace the original `request.raw`
              // property
}

exports.res(response)

The default response serializer. Returns an object:

{
  statusCode: Number, // Response status code, will be null before headers are flushed
  headers: Object, // The headers to be sent in the response.
  raw: Object // Non-enumerable, i.e. will not be in the output, original
              // response object. This is available for subsequent serializers
              // to use.
}

exports.wrapErrorSerializer(customSerializer)

A utility method for wrapping the default error serializer. This allows custom serializers to work with the already serialized object.

The customSerializer accepts one parameter — the newly serialized error object — and returns the new (or updated) error object.

exports.wrapRequestSerializer(customSerializer)

A utility method for wrapping the default request serializer. This allows custom serializers to work with the already serialized object.

The customSerializer accepts one parameter — the newly serialized request object — and returns the new (or updated) request object.

exports.wrapResponseSerializer(customSerializer)

A utility method for wrapping the default response serializer. This allows custom serializers to work with the already serialized object.

The customSerializer accepts one parameter — the newly serialized response object — and returns the new (or updated) response object.

License

MIT License