htaccess: mod_expires.c except one or multiple folders

Question

To the following browser caching via mod_expires.c in the .htaccess...

<IfModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access plus 1 day"
</IfModule>

...I would like to add an exception: One or more folders shall not be cached. I tried a version with Directory before </IfModule>, but that led to a 500 Internal Server Error. That

<Directory "/absolute/path/to/specialfolder">
ExpiresActive On
ExpiresDefault "access plus 1 seconds"
</Directory>

and that snippet

<Directory "/absolute/path/to/specialfolder">
ExpiresActive Off
</Directory>

What's wrong and what could help? (for one or a few folders)

Answer 1

The <Directory> directive is not permitted in a .htaccess context, it can only be used in a server (or virtualhost) context. (Hence the 500 error.)

The userland/.htaccess way would be to create another .htaccess file in that "specialfolder" with ExpiresActive Off in order to override the parent config.

Alternatively, you could perhaps use an <If> expression in the root .htaccess file.

For example:

# Turn off mod_expires for a specific directory
<If "%{REQUEST_URI} =~ m#^/specialfolder/#"> 
    ExpiresActive Off
</If>

Where REQUEST_URI is the document-root-relative URL-path.

OR, only use mod_expires when not requesting these folder(s). For example:

# Only use mod_expires when NOT requesting the specific directories
<If "%{REQUEST_URI} !~ m#^/(specialfolder|anotherfolder)/#"> 
ExpiresActive On
ExpiresDefault "access plus 1 day"
</IfModule>

One or more folders shall not be cached.

Although disabling mod_expires does not necessarily prevent the resource from being cached. It simply prevents mod_expires from setting the Cache-Control (and Expires) headers. If you specifically want to disable caching then consider explicitly setting the relevant Cache-Control/Expires header(s) directly.

For example:

# Set env var when special "none-cache" folder requested:
SetEnvIf Request_URI "^/(specialfolder|anotherfolder)/" NOCACHE

# Set no-cache headers if NOCACHE env var is set
Header always set Cache-Control "no-store" env=NOCACHE
Header always set Expires "0" env=NOCACHE

In this example, you do not need to disable mod_expires since the Header directive will override mod_expires (since mod_headers is processed after mod_expires).