Enabling various modules

Besides the http and mail modules, there are a number of other modules included in the NGINX distribution. These modules are not activated by default, but may be enabled by setting the appropriate configuration option:

--with-<module-name>_module

Table – HTTP module configure options

Option	Explanation
--with-http_ssl_module	If you need to encrypt web traffic, you will need this option to be able to use URLs beginning with https. (Requires the OpenSSL library.)
--with-http_realip_module	If your NGINX is behind an L7 load balancer or other device that passes the client's IP address in an HTTP header, you will need to enable this module. For use in situations where multiple clients appear to come from one IP address.
--with-http_addition_module	This module works as an output filter, enabling you to add content of a different location before or after that of the location itself.
--with-http_xslt_module	This module will handle transformations of XML responses, based on one or more XSLT stylesheets. (Requires the libxml2 and libxslt libraries.)
--with-http_image_filter_module	This module is able to act as a filter on images, processing them before handing them over to the client. (Requires the libgd library.)
--with-http_geoip_module	With this module, you are able to set various variables to use in configuration blocks to make decisions based on the geographic location found for a client's IP address. (Requires the MaxMind GeoIP library and the corresponding precompiled database files.)
--with-http_sub_module	This module implements a substitution filter, replacing one string in the response with another. (A word of caution: using this module implicitly disables the caching of headers.)
--with-http_dav_module	Enabling this module will activate the configuration directives for using WebDAV. Note that this module should only be enabled on a need-to-use basis, as it could present security problems if configured incorrectly.
--with-http_flv_module	If you need to be able to stream Flash video files, this module will provide pseudo-streaming.
--with-http_mp4_module	This module supports pseudo-streaming for H.264/AAC files.
--with-http_gzip_static_module	Use this module if you would like to support sending pre-compressed versions of static files when the resource is called without the .gz ending.
--with-http_gunzip_module	This module will decompress pre-compressed content for clients that do not support gzip encoding.
--with-http_random_index_module	If you would like to serve an index file chosen at random from the files in a directory, then this module needs to be enabled.
--with-http_secure_link_module	This module provides a mechanism to hash a link to a URL, so that only those with the proper password would be able to calculate the link.
--with-http_stub_status_module	Enabling this module will help you gather statistics from NGINX itself. The output can be graphed using RRDtool or something similar.

As you can see, these are all modules that build upon the http module, providing extra functionality. Enabling the modules at compile time should not affect runtime performance at all. Using the modules later in the configuration is where performance may be impacted.

I would therefore recommend the following configure options for a web accelerator/proxy:

$ ./configure --with-http_ssl_module --with-http_realip_module --with-http_geoip_module --with-http_stub_status_module --with-openssl=${BUILD_DIR}/openssl-1.0.1p

And the following for a web server:

$ ./configure --with-http_stub_status_module

The difference lies in where NGINX will be faced with clients. The web acceleration role takes care of terminating SSL requests as well as dealing with proxied clients and making decisions based on where a client came from. The web server role only needs to provide default file serving capability.

I would recommend always enabling the stub_status module, as it provides a means of gathering metrics on how your NGINX is performing.

Disabling unused modules

There are also a number of http modules that are normally activated, but may be disabled by setting the appropriate configuration option --without-<module-name>_module. If you have no use for these modules in your configuration, you can safely disable them.

Table – Disable configure options

Option	Explanation
--without-http_charset_module	The charset module is responsible for setting the Content-Type response header, as well as converting from one charset to another.
--without-http_gzip_module	The gzip module works as an output filter, compressing content as it's delivered to the client.
--without-http_ssi_module	This module is a filter that processes Server Side Includes. If the Perl module is enabled, an additional SSI command (perl) is available.
--without-http_userid_module	The userid module enables NGINX to set cookies that can be used for client identification. The variables $uid_set and $uid_got can then be logged for user tracking.
--without-http_access_module	The access module controls access to a location based on IP address.
--without-http_auth_basic_module	This module limits access via HTTP Basic Authentication.
--without-http_autoindex_module	The autoindex module enables NGINX to generate a directory listing for directories that have no index file.
--without-http_geo_module	This module enables you to set up configuration variables based on a client's IP address and then take action on the value of those variables.
--without-http_map_module	The map module enables you to map one variable to another.
--without-http_split_clients_module	This module creates variables that can be used for A/B testing.
--without-http_referer_module	This module enables NGINX to block requests based on the Referer HTTP header.
--without-http_rewrite_module	The rewrite module allows you to change URIs based on various conditions.
--without-http_proxy_module	The proxy module allows NGINX to pass requests onto another server or group of servers.
--without-http_fastcgi_module	The FastCGI module enables NGINX to pass requests to a FastCGI server.
--without-http_uwsgi_module	This module enables NGINX to pass requests to a uWSGI server.
--without-http_scgi_module	The SCGI module enables NGINX to pass requests to an SCGI server.
--without-http_memcached_module	This module enables NGINX to interact with a memcached server, placing responses to queries into a variable.
--without-http_limit_conn_module	This module enables NGINX to set connection limits based on certain keys, usually an IP address.
--without-http_limit_req_module	With this module, NGINX can limit the request rate per key.
--without-http_empty_gif_module	The empty GIF module produces a 1 x 1-pixel in-memory transparent GIF.
--without-http_browser_module	The browser module allows for configurations based on the User-Agent HTTP request header. Variables are set based on the version found in this header.
--without-http_upstream_ip_hash_module	This module defines a set of servers that may be used in conjunction with the various proxy modules.