The ngx_http_ssi_module module is a filter that processes SSI (Server Side Includes) commands in responses passing through it. Currently, the list of supported SSI commands is incomplete.

location / {
    ssi on;
    ...
}

ssi off;

Enables or disables processing of SSI commands in responses.

ssi_last_modified off;

Allows to preserve the “Last-Modified” header field from the original response during SSI processing to facilitate response caching.

By default, the header field is removed as contents of the response are modified during processing and may contain dynamically generated elements or parts that are changed independently of the original response.

ssi_min_file_chunk 1k;

Sets the minimum size for parts of a response stored on disk, starting from which it makes sense to send them using sendfile.

ssi_silent_errors off;

Allows to suppress output of the string “[an error occurred while processing the directive]” if an error occurred during SSI processing.

ssi_types text/html;

Enables processing of SSI commands in responses with the specified MIME types in addition to “text/html”. The special value “*” matches any MIME type (0.8.29).

ssi_value_length 256;

Sets the maximum length for values of parameters in SSI commands.

SSI commands have the following generic format:

<!--# command parameter1=value1 parameter2=value2 ... -->

The following commands are supported:

block

Defines a block that can be used as a stub in the include command. The block can contain other SSI commands. The command has the following parameter:

name

block name.

Example:

<!--# block name="one" -->
stub
<!--# endblock -->

config

Sets some parameters used during SSI processing, namely:

errmsg

a string that is output if an error occurs during SSI processing. By default, the following string is output:

[an error occurred while processing the directive]

timefmt

a format string passed to the strftime() function used to output date and time. By default, the following format is used:

"%A, %d-%b-%Y %H:%M:%S %Z"

The “%s” format is suitable to output time in seconds.

echo

Outputs the value of a variable. The command has the following parameters:

var

variable name.

encoding

encoding method. Possible values include none, url, and entity. By default, entity is used.

default

non-standard parameter that sets a string to be output if a variable is undefined. By default, “none” is output. The command

<!--# echo var="name" default="no" -->

replaces the following sequence of commands:

<!--# if expr="$name" --><!--# echo var="name" --><!--#
       else -->no<!--# endif -->

if

Performs a conditional inclusion. The following commands are supported:

<!--# if expr="..." -->
...
<!--# elif expr="..." -->
...
<!--# else -->
...
<!--# endif -->

Only one level of nesting is currently supported. The command has the following parameter:

expr

expression. An expression can be:

• variable existence check:

  <!--# if expr="$name" -->
  

• comparison of a variable with a text:

  <!--# if expr="$name = text" -->
  <!--# if expr="$name != text" -->
  

• comparison of a variable with a regular expression:

  <!--# if expr="$name = /text/" -->
  <!--# if expr="$name != /text/" -->
  

If a text contains variables, their values are substituted. A regular expression can contain positional and named captures that can later be used through variables, for example:

<!--# if expr="$name = /(.+)@(?P<domain>.+)/" -->
    <!--# echo var="1" -->
    <!--# echo var="domain" -->
<!--# endif -->

include

Includes the result of another request into a response. The command has the following parameters:

file

specifies an included file, for example:

<!--# include file="footer.html" -->

virtual

specifies an included request, for example:

<!--# include virtual="/remote/body.php?argument=value" -->

Several requests specified on one page and processed by proxied or FastCGI servers run in parallel. If sequential processing is desired, the wait parameter should be used.

stub

non-standard parameter that names the block whose content will be output if an included request results in an empty body or if an error occurs during request processing, for example:

<!--# block name="one" -->&nbsp;<!--# endblock -->
<!--# include virtual="/remote/body.php?argument=value" stub="one" -->

The replacement block content is processed in the included request context.

wait

non-standard parameter that instructs to wait for a request to fully complete before continuing with SSI processing, for example:

<!--# include virtual="/remote/body.php?argument=value" wait="yes" -->

set

non-standard parameter that instructs to write a successful result of request processing to the specified variable, for example:

<!--# include virtual="/remote/body.php?argument=value" set="one" -->

It should be noted that only the results of responses obtained using the ngx_http_proxy_module and ngx_http_memcached_module modules can be written into variables.

set

Sets a value of a variable. The command has the following parameters:

var

variable name.

value

variable value. If an assigned value contains variables, their values are substituted.

The ngx_http_ssi_module module supports two embedded variables:

$date_local

current time in local time zone. The format is set by the config command with the timefmt parameter.

$date_gmt

current time in GMT. The format is set by the config command with the timefmt parameter.