Awesome

HTTP Concatenation module for Nginx

Introduction

This is a module that is distributed with tengine which is a distribution of Nginx that is used by the e-commerce/auction site Taobao.com. This distribution contains some modules that are new on the Nginx scene. The ngx_http_concat module is one of them.

The module is inspired by Apache's modconcat. It follows the same pattern for enabling the concatenation. It uses two ?, like this:

http://example.com/??style1.css,style2.css,foo/style3.css

If a third ? is present it's treated as version string. Like this:

http://example.com/??style1.css,style2.css,foo/style3.css?v=102234

Configuration example

location /static/css/ {
    concat on;
    concat_max_files 20;
}
    
location /static/js/ {
    concat on;
    concat_max_files 30;
}

Module directives

concat on | off

default: concat off

context: http, server, location

It enables the concatenation in a given context.

concat_types MIME types

default: concat_types: text/css application/x-javascript

context: http, server, location

Defines the MIME types which can be concatenated in a given context.

concat_unique on | off

default: concat_unique on

context: http, server, location

Defines if only files of a given MIME type can concatenated or if several MIME types can be concatenated. For example if set to off then in a given context you can concatenate Javascript and CSS files.

Note that the default value is on, meaning that only files with same MIME type are concatenated in a given context. So if you have CSS and JS you cannot do something like this:

http://example.com/static/??foo.css,bar/foobaz.js

In order to do that you must set concat_unique off. This applies to any other type of files that you decide to concatenate by adding the respective MIME type via concat_types,

concat_max_files numberp

default: concat_max_files 10

context: http, server, location

Defines the maximum number of files that can be concatenated in a given context. Note that a given URI cannot be bigger than the page size of your platform. On Linux you can get the page size issuing:

getconf PAGESIZE

Usually is 4k. So if you try to concatenate a lot of files together in a given context you might hit this barrier. To overcome that OS defined limitation you must use the large_client_header_buffers directive. Set it to the value you need.

concat_delimiter: string

default: NONE

context: http, server, locatione

Defines the delimiter between two files. If the config is concat_delimiter "\n",a '\n' would be inserted betwen 1.js and 2.js when visted http://example.com/??1.js,2.js

concat_ignore_file_error: on | off

default: off

context: http, server, location

Whether to ignore 404 and 403 or not.

Installation

Clone the git repo.

git clone git://github.com/alibaba/nginx-http-concat.git

Add the module to the build configuration by adding --add-module=/path/to/nginx-http-concat.
Build the nginx binary.
Install the nginx binary.
Configure contexts where concat is enabled.
Build your links such that the above format, i.e., all URIs that have files that are to be concatenated have a ?? prefix. The HTML produced would have something like this inside the <head> element for concatenating CSS files.
```
<link rel="stylesheet" href="??foo1.css,foo2.css,subdir/foo3.css?v=2345" />
 
```
Similarly for Javascript files you should have:
```
<script src="??bar1.js,bar22.css,subdir/bar3.js?v=3245" />
 
```
Now if you open up the network tab on firebug or on safari/chrome/chromium browser inspector you should see a single bar where before there were many. Congratulations you're now using file concatenation at the server level. No longer messing around with scripts for aggregating files. Note although that there's no minification of files. So you might want to minify the files before concatenating them.
Done.

Tagging releases

Perusio is maintaing a tagged release at http://github.com/alibaba/nginx-http-concat in synch with the Tengine releases. Refer there for the latest uncommitted tags.

Other tengine modules on Github

footer filter: allows to add some extra data (markup or not) at the end of a request body. It's pratical for things like adding time stamps or other miscellaneous stuff without having to tweak your application.
http slice: allows to serve a file by slices. A sort of reverse byte-range. Useful for serving large files while not hogging the network.

Other builds

As referred at the outset this module is part of the tengine Nginx distribution. So you might want to save yourself some work and just build it from scratch using tengine in lieu if the official Nginx source.
If you fancy a bleeding edge Nginx package (from the dev releases) for Debian made to measure then you might be interested in Perusio's HA/HP debian Nginx package with built-in support for nginx-http-concat. Instructions for using the repository and making the package live happily inside a stable distribution installation are provided.

Acknowledgments

Thanks to Joshua Zhu and the Taobao platform engineering team for releasing tengine. Also for being kind enough to clarify things regarding this module on the Nginx mailing list.

License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.