I am trying to implement a logger in node js which will create a new log file every day on a custom format for logs
for this i have used three packages
so the final output should every day a new log file should create in logs folder and it should log all the http(morgan logs) and typed logs (winston logs) into a single file in the below format
Date || Filename || statusCode || logMessage || uuid (for tracing)
eg: Fri Jan 18 2019 13:48:18 GMT+0530 (IST) || [index.js] || 200 || calling the new route || 287dccb0-1afa-11e9-88a0-dfb1c665be9d
so for this i have written three files index.js(root file of nodejs) logger.js(logger implementation and configuration) and logger.test.js(test cases for logger using jest)
additional packages
the problems that i have
- if i put a logger.error({message: {statusCode:200, logMsg: "the server will be starting in port 3000"}}) in the index.js on app.listen before to console.log() the uuid is null
- the test cases that i have written is wrong, i am new to jest i just want to know how can i check all that cases.
- why when i test the suits uuid is null, how can i pass the uuid for test cases also
- how can i check whether new folder will be created and if already logs folder are there new file is created kind of test cases.
- How can i add other levels , info, debuge , warn based on the env. How can i improve this code to implement the logger functionality
// index.js
const app = require('express')();
const cors = require('cors')
const morgan = require('morgan') // HTTP request logger middleware
const logger = require('./config/logger')(module) //Logger
const uuid = require('uuid')
const httpContext = require('express-http-context')
// Use any third party middleware that does not need access to the context here
// app.use(some3rdParty.middleware);
app.use(httpContext.middleware);
// all code from here on has access to the same context for each request
// Run the context for each request.
// Assigning a unique identifier to each request
app.use((req, res, next) => {
httpContext.set('reqId', uuid.v1());
next()
})
// using morgan with winston(logger)
app.use(morgan('combined', {
stream: {
write: (message) => logger.error(message)
}
}))
app.use(cors());
app.use("/new", (req, res) => {
logger.error({
message: {
statusCode: 400,
logMsg: "hitting new route"
}
})
nextLayer(res)
})
const nextLayer = (res) => {
logger.error({
message: {
statusCode: 400,
logMsg: "hitting in nextLayer function"
}
})
res.send("OK")
}
app.listen(4000, () => {
console.log('Server running on port 4000');
})
// Logger.js
const appRoot = require('app-root-path')
const {
createLogger,
format,
transports
} = require('winston')
const {
combine,
timestamp,
label,
printf
} = format
const path = require('path')
require('winston-daily-rotate-file');
const httpContext = require('express-http-context')
/**
* @method checkMessageProp
* @param {message} can be object if developer defined, else it will be string
* if its a network request
* @returns a fixed format how the status code and message should show
*/
const checkMessageProp = (message) => {
switch (typeof message) {
case "object":
const {
statusCode,
logMsg
} = message
return `${statusCode ? statusCode : "Not Defined"} || ${logMsg ? logMsg : "Not Defined"}`;
case "string":
let messageSplit = message.split(`"`)
var message = messageSplit ? `${messageSplit[2].trim().split(" ")[0]} || ${messageSplit[1]}` : null
return message
default:
return message
}
}
/**
* @method customFormat
* @param {log} the log passed by the developer or based on network requests
* @returns a customFormat how it should be logged to the log files
*/
const customFormat = printf(log => {
const now = new Date();
const reqId = httpContext.get('reqId');
return `${log.timestamp ? new Date(log.timestamp) : now} || [${log.label}] || ${checkMessageProp(log.message)} || ${reqId ? reqId : null}`
});
/**
* @method getFileName
* @param {moduleObj} the module realted object passed from the require of logger file
* @returns the file name where the logger was invoked
*/
const getFileName = moduleObj => {
if (Object.keys(moduleObj).length > 0) {
let parts = moduleObj.filename.split(path.sep)
return parts.pop()
} else {
return "Module not passed while requiring the logger"
}
}
// Custom settings for each transport
const options = moduleObj => {
return {
dailyRotateFile: {
filename: `${appRoot}/logs/TPS-UI-%DATE%.log`,
datePattern: 'YYYY-MM-DD',
prepend: true,
level: "error",
timestamp: new Date(),
localTime: true
}
}
}
// Instantiate a Winston Logger with the settings
let logger = moduleObj => {
return createLogger({
format: combine(
label({
label: getFileName(moduleObj)
}),
customFormat
),
transports: [
new transports.DailyRotateFile(options(moduleObj).dailyRotateFile)
],
exitOnError: false // do not exit on handled exceptions
})
}
module.exports = logger
// logger.test.js
const logger = require('./logger')
beforeEach(() => {
mockLoggerMessageObject = {
message: {
statusCode: 400,
logMsg: "Calling in test suite"
}
}
mockLoggerMessageString = `::ffff:127.0.0.1 - - [18/Jan/2019:04:50:57 +0000]
"GET /new HTTP/1.1" 200 2 "http://localhost/" "Mozilla/5.0
(linux) AppleWebKit/537.36 (KHTML, like Gecko) jsdom/11.12.0"`
mockLoggerMessageNumberFormat = 123
mockLoggerMessageArrayFormat = ["data", "test", 123]
})
describe(`Logger test cases`, () => {
test('should invoke the logger function with the mock Logger message object', () => {
expect(logger(module).error(mockLoggerMessageObject)).toBeDefined()
})
test(`should invoke the logger function with empty object`, () => {
expect(logger(module).error({})).toBeDefined()
})
test(`should invoke the logger function without any module object`, () => {
expect(logger({}).error(mockLoggerMessageObject)).toBeDefined()
})
test(`should invoke the logger function without any module and message object`, () => {
expect(logger({}).error({})).toBeDefined()
})
test(`should invoke the logger function with the http request`, () => {
expect(logger(module).error(mockLoggerMessageString)).toBeDefined()
})
test(`should invoke the logger function with the number format`, () => {
expect(logger(module).error(mockLoggerMessageNumberFormat)).toBeDefined()
})
test(`should invoke the logger function with the array format`, () => {
expect(logger(module).error(mockLoggerMessageArrayFormat)).toBeDefined()
})
})
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