micrologger

Simple but meaningful application and request logs to be used with koa microservices

Support for rotating files and/or sending to a logging collector fluentd (more to come)

Add to the top of your koa application and pass in koa app to get started:

const app = require('koa')();
const logger = require('micrologger');
app.use(logger());

This will give you all application and request logs:

Make sure to pass NODE_ENV=development for local development logs

Rotating log files will be saved to 'logs/out.log' in the root of your app. Pass logToFile:true in the options and pass in NODE_ENV=developemnt to use rotating files

That is all you need for micrologger to start collecting and sending logs.

Logging severity/levels:

INFO ERROR

Fields for Request Logs: class - class field represents the origin of the request. application, client_request or service_request

host - hostname

ident - name of app from package.json

pid - process id

severity - logging level

timestamp - UTC epoch

message - log message with details about application, request, response or error

path - path of request

method - request method

request_id - UID generated to track the individual request

correlation_id - UID generated/forwarded through all services

response_time - UTC epoch of response

resolution_time - track the time for request to be resolved

status - status code

metadata - metadata specific to the request that was made. this can be specific event data that is helpful outside system logs

Example of request logging (the request)

{
  "class": "client_request",
  "ident": "app name from package.json",
  "message": "GET /status",
  "host": "some-host",
  "client": "client-ip",
  "path": "/status",
  "method": "GET",
  "request_id": "3eeb945c-f5b5-4431-a5fe-177dfae7fec5",
  "correlation_id": "d4cc5b41-c023-49bc-a55e-558093918de4",
  "request_time": "2016-12-21T21:05:57.620Z",
  "pid":17636,
  "severity": "INFO",
  "metadata": {}
}

Example of request logging (the response)

{
  "class": "client_request",
  "ident": "app name from package.json",
  "message": "200 OK /",
  "host": "some-host",
  "client": "client-ip",
  "path": "/status",
  "method": "GET",
  "request_id": "33931f5e-9915-466c-9d23-10977ab48da6",
  "correlation_id": "d4cc5b41-c023-49bc-a55e-558093918de4",
  "response_time": "2016-12-21T21:05:57.920Z",
  "resolution_time": "300ms",
  "status": 200,
  "pid":17636,
  "severity": "INFO",
  "metadata": {},
}

The correlation id will be generated if the x-correlation-id isn't found in the header. Services should pass this along in the header.

NODE_ENV=development node server

For local development you will get the following in the console: system errors, request, and response

You can add fluentd as a collector

add the fluent block below and all the logs will be sent to fluentd

app.use(logger({
  fluent: {
    host: '127.0.0.1',
    port: '24224'
  }
}))

node server

Example of application error in /logs/out.log

{
  "class": "application",
  "host": "some-host",
  "pid": 40293,
  "severity": "ERROR",
  "timestamp": "2016-12-21T18:00:08.582Z",
  "message": "ReferenceError: thi is not defined at Object.module.exports.post ...rest of stack trace"
}

Log info/error

logger.info('Info Message');
logger.error('Some error message');

The info and error message will be logged with the following structure:

{
  "class": "application",
  "host": "some-host",
  "pid": 40293,
  "severity": "INFO",
  "timestamp": "2016-12-21T18:00:08.582Z",
  "message": "Info Message"
}

{
  "class": "application",
  "host": "some-host",
  "pid": 40293,
  "severity": "ERROR",
  "timestamp": "2016-12-21T18:00:08.582Z",
  "message": "Some error message"
}

All options

app.use(logger({
  logsToFile: false,
  appLogs: true,
  backgroundColor: 'dark',
  fluent: {
    host: '127.0.0.1',
    port: '24224'
  }
}))

• logToFile: (optional, default is false)
• appLogs: (optional, default is true) if set to false application errors will not be logged. This does not include request errors
• backgroundColor: (optional) this is the background color of your terminal. options are dark/light (default is dark)
• fluent with host, port