logzio-node-debug
v3.1.1
Published
A nodejs debug wrapper for logz.io
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logzio-node-debug
A nodejs debug wrapper for logz.io
This library is ES6 thus suitable for Node development and not for browser.
This lib quite opinionated in a way. In case somebody needs to change it. We can parametrized:
- all
namespace
s will be sent to Logz.io in the message - log levels are
{level: debug}
or{level: error}
Installation
npm install logzio-node-debug --save
Sample usage
Initialize the lib with Logz.io options:
const logzOptions = { // Params doc: https://github.com/logzio/logzio-nodejs#options
token: `${logzio_token}`,
type: `${the_app_you_wanna_track}`
}
require('logzio-node-debug').init(logzOptions)
Create loggers, providing a namespace, for every file where you want to use logging (just like u're used to with debug):
const debug = require('logzio-node-debug').debug('your-project:server')
const error = require('logzio-node-debug').debug('your-project:server:error')
debug('I am debug')
error('I am error')
MDC - Mapped Diagnostic Context
Inspired by Logback's implementation of SLF4J MDC API
MDC allows you to store extra data which will be automagically appended to every log entry as long as you stay in the current context. In Logz.io, the MDC keys will be shown as Fields and can be used as filter parameters.
Compatiblity issue
We have moved to cls-hooked
instead of continuation-local-storage
so that the lib is compatible with async/await.
This causes the MDC to work with NodeJS versions 8+. If any of you need MDC to work with lower versions, create a PR
with a switch to cls-hooked
and continuation-local-storage
. Thank you. ;)
MDC API
MDC.createContext(next)
Creates MDC context. Has to be called before calling put
, otherwise put
will have no effect.
It is possible to create nested contexts. In that case, all MDC data from parent context will be copied to child context, therefore all modifications to MDC in the child context will be done independently from the parent context.
The next
parameter is context callback. MDC data will be valid during the whole duration of the callback. This makes it ideal to call this in a middleware function (see request-id.middleware.js for example).
const MDC = require('logzio-node-debug').MDC
MDC.createContext(doStuff)
Or, if you want to create a context with one or more values already initialized:
const MDC = require('logzio-node-debug').MDC
MDC.createContext(() => {
MDC.put('foo', 'bar')
doStuff()
})
Or, as an Express middleware function:
const MDC = require('logzio-node-debug').MDC
function mdcMiddleware(req, res, next) {
MDC.createContext(() => {
MDC.put('foo', 'bar')
next()
})
}
MDC.getAll()
Returns the whole MDC object.
MDC.get(key)
Returns the value of the key
in MDC.
MDC.put(key, value)
Sets the value
of key
in MDC.
MDC.remove(key)
Sets the key
to undefined
.
MDC.clear()
Removes all data from MDC.
One example to explain them all
MDC.createContext(() => {
MDC.put('foo', '1')
doStuff()
})
function doStuff() {
MDC.put('bar', 2)
MDC.get('foo') // => '1'
MDC.getAll() // => {foo: '1', bar: 2}
MDC.remove('foo')
MDC.getAll() // => {bar: 2}
MDC.clear()
MDC.getAll() // => {}
}
Request ids in logs
A common use-case for MDC is adding a requestId
to all incoming requests. If you have some concurrent request (which you for sure have in prod ;-) then you can filter logs by requestId
.
To enable this functionality, you can use pre-implemented express
middleware requestIdMiddleware
. Just add it to your app middlewares, probably somewhere in app.js:
const requestIdMiddleware = require('logzio-node-debug').requestIdMiddleware
app.use(requestIdMiddleware)
In Logz.io/Kibana use field requestId
to filter your logs.
Tests
While testing you will probably need no Logz.io at all. In that case, just don't initialize the lib with
require('logzio-node-debug').init
.
Log level
2 log levels will be appended to your message - {level: debug} or {level: error}.
That's all folks
Enjoy the colorful console logs and logz.io side by side.