nodejs开发中间件morgan

## API

```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.

#### 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)`.

```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:

```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.

##### :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.

##### :res[header]

The given `header` of the response.

##### :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 function for use by `morgan`. A format string

is a string that represents a single log line and c
a604
an 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`.

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 date in the `log/` directory using the

[file-stream-rotator module](https://www.npmjs.com/package/file-stream-rotator).

```js

var FileStreamRotator = require('file-stream-rotator')

var express = require('express')

var fs = require('fs')

var morgan = require('morgan')

var path = require('path')

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 = FileStreamRotator.getStream({

  date_format: 'YYYYMMDD',

  filename: path.join(logDirectory, 'access-%DATE%.log'),

  frequency: 'daily',

  verbose: false

})

// setup the logger

app.use(morgan('combined', {stream: accessLogStream}))

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()

}