An Apache trick: using directories to create redirections
Suppose, not entirely hypothetically, that you're using Apache
ProxyPass directives as a reverse proxy to map /someurl/
on your
website to another web server. You generally have to redirect the
URL with the trailing slash, but of course you
would like a request for a plain '/someurl
' to also work right
instead of just getting a 404 status response. Here, 'work right'
means that you'll generate a redirection from '/someurl
' to
'/someurl/
'.
It's certainly possible to do this with one of the various Apache
directives for explicit redirections (I'd use RedirectMatch
).
But often there's an easier way: use a real filesystem directory.
If somedir
is a directory in the Apache document root and you
send a request for '/somedir
', Apache's default behavior is to
send exactly the redirection we want. And Apache doesn't care if
the '/somedir/
' URL is being diverted somewhere other than the
filesystem (via ProxyPass or other directives); it will still send
that redirection regardless.
So we can just do 'mkdir /docroot/someurl
' and everything will
work. The directory contents don't matter; I tend to put a README
file there with a note about how the directory is just there for
the redirection and actual contents in it will be ignored.
(This redirection trick happens automatically if you're using
.htaccess
files in a directory to control, say, internal
redirections. However there are various
reasons for not using .htaccess
files, including centralizing
your configuration in one easily visible place instead of spraying
it all over the filesystem in a bunch of nominally invisible files.)
Back when I wrote my entry on ProxyPass, I theorized about using this trick. I can now say that we've actually done this in our configuration and it works fine.
(This trick is a very old one, of course; I'm sure people have been doing it in Apache for ages. I just feel like writing it down explicitly for various reasons.)
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