Apache: fall-back mechanism

 

This is the recent requirement that i had faced w.r.t. virtual hosts.

1. at a given location see if the static resource exist
2. if it exist then serve form that location
3. otherwise fallback to a default location

after a day of investigation… this was the solution i finally discovered

 

NameVirtualHost *:81

#telling virtual host to listen on this port
<VirtualHost *:81> 
    ErrorLog logs/rewrite-log 
    CustomLog logs/rewrite-log combined 
    DocumentRoot E:/proj/nono2_2_10_3/config/
    LogLevel debug
    
    <IfModule rewrite_module> 
        RewriteLog logs/rewrite.log 
        RewriteLogLevel 3
    </IfModule> 

    RewriteEngine on    
    

    #if the file at the below path doesnt exist then the rule applies. Both these are part of the same rule
    RewriteCond %{DOCUMENT_ROOT}httpd/templates-mobile/js/$3 !-f

    #rule is to serve the files from default templates folder and skip the next rule (see s=1). Make this rule as the last rule(see L)

    #note the $1,$2,$3 are interpreted from he below rule. Each ‘()’ represents $n. where n increments per bracket

    # the above rewriteCond take $1,2,3 from this rule below
    RewriteRule ^(/ui)(/tpl/js)(.+)$ %{DOCUMENT_ROOT}httpd/templates/js/$3 [L,S=1]

    #serve from templates-mobile folder     
    RewriteRule ^(/ui)(/tpl/js)(.+)$ %{DOCUMENT_ROOT}httpd/templates-mobile/js/$3 [L]
        
</VirtualHost> 

Hope this helps somebody…