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# morgan
[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Build Status][travis-image]][travis-url]
[![Test Coverage][coveralls-image]][coveralls-url]
HTTP request logger middleware for node.js
> Named after [Dexter](http://en.wikipedia.org/wiki/Dexter_Morgan), a show you should not watch until completion.
## API
<!-- eslint-disable no-unused-vars -->
```js
var morgan = require('morgan')
```
### morgan(format, options)
Create a new morgan logger middleware function using the given `format` and `options`.
The `format` argument may be a string of a predefined name (see below for the names),
a string of a format string, or a function that will produce a log entry.
The `format` function will be called with three arguments `tokens`, `req`, and `res`,
where `tokens` is an object with all defined tokens, `req` is the HTTP request and `res`
is the HTTP response. The function is expected to return a string that will be the log
line, or `undefined` / `null` to skip logging.
#### Using a predefined format string
<!-- eslint-disable no-undef -->
```js
morgan('tiny')
```
#### Using format string of predefined tokens
<!-- eslint-disable no-undef -->
```js
morgan(':method :url :status :res[content-length] - :response-time ms')
```
#### Using a custom format function
<!-- eslint-disable no-undef -->
``` js
morgan(function (tokens, req, res) {
return [
tokens.method(req, res),
tokens.url(req, res),
tokens.status(req, res),
tokens.res(req, res, 'content-length'), '-',
tokens['response-time'](req, res), 'ms'
].join(' ')
})
```
#### Options
Morgan accepts these properties in the options object.
##### immediate
Write log line on request instead of response. This means that a requests will
be logged even if the server crashes, _but data from the response (like the
response code, content length, etc.) cannot be logged_.
##### skip
Function to determine if logging is skipped, defaults to `false`. This function
will be called as `skip(req, res)`.
<!-- eslint-disable no-undef -->
```js
// EXAMPLE: only log error responses
morgan('combined', {
skip: function (req, res) { return res.statusCode < 400 }
})
```
##### stream
Output stream for writing log lines, defaults to `process.stdout`.
#### Predefined Formats
There are various pre-defined formats provided:
##### combined
Standard Apache combined log output.
```
:remote-addr - :remote-user [:date[clf]] ":method :url HTTP/:http-version" :status :res[content-length] ":referrer" ":user-agent"
```
##### common
Standard Apache common log output.
```
:remote-addr - :remote-user [:date[clf]] ":method :url HTTP/:http-version" :status :res[content-length]
```
##### dev
Concise output colored by response status for development use. The `:status`
token will be colored red for server error codes, yellow for client error
codes, cyan for redirection codes, and uncolored for all other codes.
```
:method :url :status :response-time ms - :res[content-length]
```
##### short
Shorter than default, also including response time.
```
:remote-addr :remote-user :method :url HTTP/:http-version :status :res[content-length] - :response-time ms
```
##### tiny
The minimal output.
```
:method :url :status :res[content-length] - :response-time ms
```
#### Tokens
##### Creating new tokens
To define a token, simply invoke `morgan.token()` with the name and a callback function.
This callback function is expected to return a string value. The value returned is then
available as ":type" in this case:
<!-- eslint-disable no-undef -->
```js
morgan.token('type', function (req, res) { return req.headers['content-type'] })
```
Calling `morgan.token()` using the same name as an existing token will overwrite that
token definition.
The token function is expected to be called with the arguments `req` and `res`, representing
the HTTP request and HTTP response. Additionally, the token can accept further arguments of
it's choosing to customize behavior.
##### :date[format]
The current date and time in UTC. The available formats are:
- `clf` for the common log format (`"10/Oct/2000:13:55:36 +0000"`)
- `iso` for the common ISO 8601 date time format (`2000-10-10T13:55:36.000Z`)
- `web` for the common RFC 1123 date time format (`Tue, 10 Oct 2000 13:55:36 GMT`)
If no format is given, then the default is `web`.
##### :http-version
The HTTP version of the request.
##### :method
The HTTP method of the request.
##### :referrer
The Referrer header of the request. This will use the standard mis-spelled Referer header if exists, otherwise Referrer.
##### :remote-addr
The remote address of the request. This will use `req.ip`, otherwise the standard `req.connection.remoteAddress` value (socket address).
##### :remote-user
The user authenticated as part of Basic auth for the request.
##### :req[header]
The given `header` of the request. If the header is not present, the
value will be displayed as `"-"` in the log.
##### :res[header]
The given `header` of the response. If the header is not present, the
value will be displayed as `"-"` in the log.
##### :response-time[digits]
The time between the request coming into `morgan` and when the response
headers are written, in milliseconds.
The `digits` argument is a number that specifies the number of digits to
include on the number, defaulting to `3`, which provides microsecond precision.
##### :status
The status code of the response.
If the request/response cycle completes before a response was sent to the
client (for example, the TCP socket closed prematurely by a client aborting
the request), then the status will be empty (displayed as `"-"` in the log).
##### :url
The URL of the request. This will use `req.originalUrl` if exists, otherwise `req.url`.
##### :user-agent
The contents of the User-Agent header of the request.
### morgan.compile(format)
Compile a format string into a `format` function for use by `morgan`. A format string
is a string that represents a single log line and can utilize token syntax.
Tokens are references by `:token-name`. If tokens accept arguments, they can
be passed using `[]`, for example: `:token-name[pretty]` would pass the string
`'pretty'` as an argument to the token `token-name`.
The function returned from `morgan.compile` takes three arguments `tokens`, `req`, and
`res`, where `tokens` is object with all defined tokens, `req` is the HTTP request and
`res` is the HTTP response. The function will return a string that will be the log line,
or `undefined` / `null` to skip logging.
Normally formats are defined using `morgan.format(name, format)`, but for certain
advanced uses, this compile function is directly available.
## Examples
### express/connect
Simple app that will log all request in the Apache combined format to STDOUT
```js
var express = require('express')
var morgan = require('morgan')
var app = express()
app.use(morgan('combined'))
app.get('/', function (req, res) {
res.send('hello, world!')
})
```
### vanilla http server
Simple app that will log all request in the Apache combined format to STDOUT
```js
var finalhandler = require('finalhandler')
var http = require('http')
var morgan = require('morgan')
// create "middleware"
var logger = morgan('combined')
http.createServer(function (req, res) {
var done = finalhandler(req, res)
logger(req, res, function (err) {
if (err) return done(err)
// respond to request
res.setHeader('content-type', 'text/plain')
res.end('hello, world!')
})
})
```
### write logs to a file
#### single file
Simple app that will log all requests in the Apache combined format to the file
`access.log`.
```js
var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
var app = express()
// create a write stream (in append mode)
var accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), { flags: 'a' })
// setup the logger
app.use(morgan('combined', { stream: accessLogStream }))
app.get('/', function (req, res) {
res.send('hello, world!')
})
```
#### log file rotation
Simple app that will log all requests in the Apache combined format to one log
file per day in the `log/` directory using the
[rotating-file-stream module](https://www.npmjs.com/package/rotating-file-stream).
```js
var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
var rfs = require('rotating-file-stream')
var app = express()
var logDirectory = path.join(__dirname, 'log')
// ensure log directory exists
fs.existsSync(logDirectory) || fs.mkdirSync(logDirectory)
// create a rotating write stream
var accessLogStream = rfs('access.log', {
interval: '1d', // rotate daily
path: logDirectory
})
// setup the logger
app.use(morgan('combined', { stream: accessLogStream }))
app.get('/', function (req, res) {
res.send('hello, world!')
})
```
### split / dual logging
The `morgan` middleware can be used as many times as needed, enabling
combinations like:
* Log entry on request and one on response
* Log all requests to file, but errors to console
* ... and more!
Sample app that will log all requests to a file using Apache format, but
error responses are logged to the console:
```js
var express = require('express')
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
var app = express()
// log only 4xx and 5xx responses to console
app.use(morgan('dev', {
skip: function (req, res) { return res.statusCode < 400 }
}))
// log all requests to access.log
app.use(morgan('common', {
stream: fs.createWriteStream(path.join(__dirname, 'access.log'), { flags: 'a' })
}))
app.get('/', function (req, res) {
res.send('hello, world!')
})
```
### use custom token formats
Sample app that will use custom token formats. This adds an ID to all requests and displays it using the `:id` token.
```js
var express = require('express')
var morgan = require('morgan')
var uuid = require('node-uuid')
morgan.token('id', function getId (req) {
return req.id
})
var app = express()
app.use(assignId)
app.use(morgan(':id :method :url :response-time'))
app.get('/', function (req, res) {
res.send('hello, world!')
})
function assignId (req, res, next) {
req.id = uuid.v4()
next()
}
```
## License
[MIT](LICENSE)
[npm-image]: https://img.shields.io/npm/v/morgan.svg
[npm-url]: https://npmjs.org/package/morgan
[travis-image]: https://img.shields.io/travis/expressjs/morgan/master.svg
[travis-url]: https://travis-ci.org/expressjs/morgan
[coveralls-image]: https://img.shields.io/coveralls/expressjs/morgan/master.svg
[coveralls-url]: https://coveralls.io/r/expressjs/morgan?branch=master
[downloads-image]: https://img.shields.io/npm/dm/morgan.svg
[downloads-url]: https://npmjs.org/package/morgan