# node-elf-logger

**Repository Path**: mirrors_TooTallNate/node-elf-logger

## Basic Information

- **Project Name**: node-elf-logger
- **Description**: A Node.js library for configurable HTTP logging following the W3C Extended Log File Format
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-18
- **Last Updated**: 2026-07-04

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

node-elf-logger
===============

This library is a simple, configurable, [node.js](http://nodejs.org)
HTTP server compatible logging implementation that complies with the
[W3C's Extended Log File Format][spec]. Major HTTP servers like IIS and Apache
have options to follow this logging format, and that has the advantage of log
viewing software that has already been written for this format.

###Features###

 * Log files produced adhere to the [W3C's Extended Log File Format specification][spec].
 * Any number of loggers may be created for an individual `http.Server` instance.
 * Highly configurable, from which fields to log, to where to save the files to, to which entries to log at all, etc.

---

`node-elf-logger` is configurable. Specifically which `#Fields` should be
logged, whether to write to a stream or file, and the log folder and file
naming scheme (organization). First look at a minimal example:

    var http = require("http"),
        elf = require("elf-logger");
    var httpServer = http.createServer(function (req, res) {
        // blah, blah
    });
    httpServer.listen(80);
    elf.createLogger(httpServer);

This will make a `node-elf-logger` instance. All requests to the
`httpServer` instance will be logged using the `elf.defaultOptions` object.
That is all that is needed to get it going!

---

No doubt you are more interested in the configuration options of
`node-elf-logger`. Supplying a second argument to the `elf.createLogger`
function uses the options specified instead of the `elf.defaultOptions`:

    elf.createLogger(httpServer, {
        dir: "/var/log/node/http",
        template: "{cs(host)}/{date}.log",
        fields: ['date','time','c-ip','cs-method','cs-uri','sc-status','cs(user-agent)']
    });

###Options Argument###

**dir**: The root directory where `node-elf-logger` should store it's log
files. This value will be prefixed onto the *template* value if present.

**template**: Defines where each HTTP request should be logged it. This can be
a String as shown above, with special filter values surrounded by `{}`
brackets. A `/` indicates a directory change.

For more fine-grained control, you may pass a `function` reference instead.
This function will be called after every HTTP request has completed, and a
log entry is about to be written. The function will be passed the `#Fields` as
an object literal as an argument, and your function must return the path and
name of log to write the entry to. You may also cancel any log entry by
returning a "falsey" value.

**stream**: A ready `WritableStream` to log all HTTP requests to, instead of
logging to a file. Supplying this property bypasses the *dir* and
*template* properties, if present.

**fields**: The `#Fields` that should be logged as defined by the
[W3C Specification][spec]. Also look at
[these examples](http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/ffdd7079-47be-4277-921f-7a3a6e610dcb.mspx?mfr=true)
for some more ideas for fields to log. The value should be an Array of
case-insensitive Strings containing an individual field to log per Array entry.

[spec]: http://www.w3.org/TR/WD-logfile.html