http_sub module

The module is a filter that modifies a response by replacing one specified string by another.

This module isn’t built by default; it should be enabled with the ‑‑with‑http_sub_module configuration parameter.

Packages in our repositories have this module built.

Example Configuration

location / {
    sub_filter '<a href="http://127.0.0.1:8080/'  '<a href="https://$host/';
    sub_filter '<img src="http://127.0.0.1:8080/' '<img src="https://$host/';
    sub_filter_once on;
}

Directives

sub_filter

Syntax:

sub_filter string replacement;

Default:

—

Context:

http, server, location

Sets a string to replace and a replacement string. The string to replace is matched ignoring the case. The string to replace and replacement string can contain variables. Several sub_filter directives can be specified on the same configuration level. These directives are inherited from the previous configuration level if and only if there are no sub_filter directives defined on the current level.

sub_filter_last_modified

Syntax:

sub_filter_last_modified on | off;

Default:

sub_filter_last_modified off;

Context:

http, server, location

Allows preserving the “Last-Modified” header field from the original response during replacement to facilitate response caching.

By default, the header field is removed as contents of the response are modified during processing.

sub_filter_once

Syntax:

sub_filter_once on | off;

Default:

sub_filter_once on;

Context:

http, server, location

Indicates whether to look for each string to replace once or repeatedly.

sub_filter_types

Syntax:

sub_filter_types mime-type …;

Default:

sub_filter_types text/html;

Context:

http, server, location

Enables string replacement in responses with the specified MIME types in addition to “text/html”. The special value “*” matches any MIME type.