Htaccess caching system in subfolder not working

Question

Sorry if this is a duplicate: I found many questions about caching system, but my problem seems to tied to the fact that the whole script is working within a subfolder.

All I need to do is implementing a simple caching system for my website, but I can't get this to work.

Here's my .htaccess file (widely commented to be clear - sorry if too many comments are confusing):

RewriteEngine on
# Map for lower-case conversion of some case-insensitive arguments:
RewriteMap lc int:tolower
# The script lives into this subfolder:
RewriteBase /mydir/

# IMAGES
#     Checks if cached version exists...
RewriteCond cache/$1-$2-$3-{lc:$4}.$5 -f
#     ...if yes, redirects to cached version...
RewriteRule ^(hello|world)\/image\/([a-zA-Z0-9\.\-_]+)\/([a-zA-Z0-9\.\-_]+)\/([a-zA-Z0-9\.\-_\s]+)\.(png|gif|jpeg?|jpg)$ cache/$1-$2-$3-{lc:$4}.$5 [L]
#     ...if no, tries to generate content dynamically.
RewriteRule ^(hello|world)\/image\/([a-zA-Z0-9\.\-_]+)\/([a-zA-Z0-9\.\-_]+)\/([a-zA-Z0-9\.\-_\s]+)\.(png|gif|jpeg?|jpg)$ index.php?look=$1&action=image&size=$2&data=$3&name=$4&format=$5 [L,QSA]

# OTHER
#     This is always non-cached.
RewriteRule ^(hello|world)\/([a-zA-Z0-9\.\-_\s]+)\/([a-zA-Z0-9\.\-_\s]+)?\/?$ index.php?look=$1&action=$2&name=$3 [QSA]

Now, the issue is that the RewriteCond seems to be always failing, as the served image is always generated by PHP. I also tried prepending a %{DOCUMENT_ROOT}, but is still not working. If I move the whole script to the root directory, it magically starts working.

What am I doing wrong?

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

Well one thing that you are doing wrong is trying to use a rewrite map in an .htaccess file. in the first place. According to the Apache documentation:

The RewriteMap directive may not be used in <Directory> sections or .htaccess files. You must declare the map in server or virtualhost context. You may use the map, once created, in your RewriteRule and RewriteCond directives in those scopes. You just can't declare it in those scopes.

If your ISP / sysadmin has already defined the lc map then you can use it. If not then you can only do case-sensitive file caching on Linux, because its FS naming is case sensitive. However, since these are internally generated images, just drop the case conversion and stick to lower case.

%{DOCUMENT_ROOT} may not be set correctly at time of mod_rewrite execution on some shared hosting configurations. See my Tips for debugging .htaccess rewrite rules for more hints. Also here is the equivalent lines from my blog's .htaccess FYI. The DR variable does work here, but didn't for my previous ISP, to I had to hard-code the parth

# For HTML cacheable blog URIs (a GET to a specific list, with no query params, 
# guest user and the HTML cache file exists) then use it instead of executing PHP

RewriteCond %{HTTP_COOKIE} !blog_user
RewriteCond %{REQUEST_METHOD}%{QUERY_STRING}  =GET                    [NC]
RewriteCond %{DOCUMENT_ROOT}html_cache/$1.html -f
RewriteRule ^(article-\d+|index|sitemap.xml|search-\w+|rss-[0-9a-z]*)$ \
                   html_cache/$1.html                                 [L,E=END:1]

Note that I bypass the cache if the user is logged on or for posts and if any query parameters are set.

Footnote

Your match patterns are complicated because you are not using the syntax of regexps: use the \w and you don't need to escape . in [ ] or / . Also the jpeg isn't right is it? So why not:

RewriteRule ^(hello|world)/image/([.\w\-]+)/([.\w\-]+)/([\w\-]+\.(png|gif|jpe?g))$  \
              cache/$1-$2-$3-$4       [L]

etc.. Or even (given that the file rule will only match for valid files in the cache)

RewriteRule ^(hello|world)/image/(.+?)/(.+?)/(.*?\.(png|gif|jpe?g))$  \
              cache/$1-$2-$3-$4       [L]

The non-greedy modifier means that (.+?) is the same as ([^/]+) so doing hacks like ../../../../etc/passwd won't walk the file hierarchy.

Htaccess caching system in subfolder not working

1 Answers1

Footnote