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concat: HTTP Concatenation module for NGINX

Installation

You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install nginx-module-concat

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/ngx_http_concat_module.so;

This document describes nginx-module-concat v1.2.3 released on Jan 15 2020.

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.



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

  1. 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.

  2. 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.

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-concat.