Apache and sub-domains: mod_rewrite

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March 1st, 2002, 02:23 AM

pidgin

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Apache and sub-domains: mod_rewrite

Hi.
I have the following domains/sub-domains on my Apache.
domain.com
and
dev.domain.com (for development)

I have a rule changing function.domain.com?*-> domain.com/cgi-bin/function.pl?*
RewriteMap lowercase int:tolower
RewriteCond ${lowercase:%{HTTP_HOST}} ^function\.domain\.com$
RewriteRule ^(.+) /cgi-bin/function.pl [PT,L]
This part is places (as should) in the virtual host definition of domain.com (in httpd.conf)

I want to do the same for dev.domain.com. meaning:
RewriteMap lowercase int:tolower
RewriteCond ${lowercase:%{HTTP_HOST}} ^function\.dev\.domain\.com$
RewriteRule ^(.+) /cgi-bin/function.pl [PT,L]
I thought I should place it in the dev.domain.com virtual host definition.

BUT - no
when URL is *.dev.domain.com is called - unless its directly dev.domain.com the applying config is that of the domain.com (not dev.domain.com like I though).
Is that the proper behavior?
What can I do to make *.dev.domain.com go thgough the dev.domain.com virtual host.
Coming to think about it - its actually ,ore an Apache question than it is mod_rewrite one, but still...

Any idea?

March 1st, 2002, 03:34 PM

freebsd

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>> RewriteRule ^(.+) /cgi-bin/function.pl [PT,L]

First off, if you want everything in under your REQUEST_URI of / to be handled by /cgi-bin/function.pl, use a internal redirect with a ruleset like so:

RewriteRule ^(.+) /server/path/no/symlink/to/function.pl [T=application/x-httpd-cgi,L]

[PT,L] is usually used to bypass rewriting. For example:

RewriteRule ^/icons/(.+) - [PT,L]

/icons directory is reserved for global use, so don't mess with it.
Your ruleset might not work with the REQUEST_URI is exact /cgi-bin/function.pl, so you would do this right after your RewriteCond like so:

RewriteRule ^/cgi-bin/function\.pl$ - [PT,L]

Next, are you sure your domain have wildcard enabled? If so, just setup a ServerAlias for that. Your whatever.dev.domain.com MUST be DNS resolvable before you can do this.

March 2nd, 2002, 04:24 AM

pidgin

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Hey. (hi freebsd)

What I do now is this... (and it seems to be working)
________________________________

<VirtualHost my.ip.add.ress>
ServerAdmin webmaster@dev.myd.com
DocumentRoot /var/www/html/dev.myd.com
ServerName dev.myd.com
ServerAlias dev.myd.com www.dev.myd.com clicks.dev.myd.com login.dev.myd.com
ErrorLog logs/dev.myd.com-error_log
CustomLog logs/dev.myd.com-access_log common
ScriptAlias /cgi-bin/ /var/www/cgi-bin/dev.myd.com/
ErrorDocument 404 http://dev.myd.com/cgi-bin/traffic/click.pl?36

Rewritelog logs/rewrite.dev.log
RewritelogLevel 9
RewriteEngine on
RewriteMap lowercase int:tolower
RewriteCond ${lowercase:%{HTTP_HOST}} ^clicks\.dev\.myd\.com$
RewriteRule ^(.+) /cgi-bin/traffic/click.pl [PT,L]

RewriteCond ${lowercase:%{HTTP_HOST}} ^login\.dev\.myd\.com$
RewriteRule ^(.+) /cgi-bin/login.pl [PT,L]

</VirtualHost>
__________________________________

So I am wondering what you meant by
RewriteRule ^(.+) /server/path/no/symlink/to/function.pl [T=application/x-httpd-cgi,L]
and the potential problems the [PT,L].

Can you clarify whats wrong with my above solution?

Thnk you.

March 2nd, 2002, 12:06 PM

freebsd

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When you want to force REQUEST_URI of anything to be handled by a script, that's equivalent to using ErrorDocument like so:

ErrorDocument 404 /cgi-bin/error.cgi?404

Apache will need further processing to determine the MIME type of the handler - error.cgi.
Like ScriptAlias directive, every file in your scriptalias'ed cgi-bin will have a MIME type of application/x-httpd-cgi enforced.

For your case, [PT] (pass thru) would work but it's no longer the ideal way to deal with a straight internal redirect as:

RewriteRule ^(.+) /cgi-bin/traffic/click.pl [PT,L]

because click.pl is not a static file but a CGI script. Therefore, according to mod_rewrite doc, 'passthrough|PT' (pass through to next handler), you are doing extra processing to determine what handler should handle to process click.pl, and it really is a CGI (or even mod_php script with application/x-httpd-php) which is unnecessary when you can tell Apache, hey, trust me, that click.pl has a application/x-httpd-cgi MIME type.

Further, what pass-thru really means is to tell mod_rewrite, hey this is beyond your duty so just ignore it and let the responsbile person (the handler) to handle it. Like I said in my previous example:

RewriteRule ^/icons/(.+) - [PT,L]

/icons/ directory is reserved for global use because it's handled by mod_alias like so:

Alias /icons/ "/www/icons/"

so it's beyond mod_rewrite's duty and the [PT] is then being used appropriately here.

March 3rd, 2002, 02:10 AM

pidgin

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Hi.
Hey Freebsd. Thx for that explanation. That part is totally clear now.

The only question I still have regarding this is:
How do I make it work so only the
http://login.dev.myd.com/
and
http://login.dev.myd.com
will go to the function, while all the rest (like login.dev.myd.com/images/log.gif) will not be effected.

This is because I only want the login.dev.... to go to the login.pl while images and other redirection should not be redirected to the cgi.

March 3rd, 2002, 06:34 AM

freebsd

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Every request under http://login.dev.myd.com/ will hit your RewriteCond regardless which ruleset you have. You will need to figure out if you really have that many other stuff (images/log.gif) then change the priority of your condition to give you the fastest and most efficient result.
For instance,

RewriteEngine on
RewriteMap lowercase int:tolower
RewriteCond ${lowercase:%{HTTP_HOST}} ^login\.dev\.myd\.com$
RewriteRule ^(.+) /server/path/to/cgi-bin/login.pl [T=application/x-httpd-cgi,L]

A request of (1) clicks.dev.myd.com/* as well as (2) login.dev.myd.com/*. To minimize the chance for requesting (1) clicks.dev.myd.com, the rule of thumb is to create ANOTHER unique <VirtualHost> block for login.dev.myd.com so your RewriteCond {HTTP_HOST} is now obsolete and you just need to deal with the (2) part.
Here is an example:

Code:

<VirtualHost my.ip.add.ress>
  ServerAdmin webmaster@dev.myd.com
  DocumentRoot /var/www/html/dev.myd.com
  ServerName login.dev.myd.com
  #ServerAlias dev.myd.com www.dev.myd.com clicks.dev.myd.com login.dev.myd.com (this line is gone)
  ErrorLog logs/login.dev.myd.com-error_log
  CustomLog logs/login.dev.myd.com-access_log common
  ScriptAlias /cgi-bin/ "/var/www/cgi-bin/dev.myd.com/"
  ErrorDocument 404 http://dev.myd.com/cgi-bin/traffic/click.pl?36
  RewriteEngine on
  Rewritelog logs/rewrite.dev.log
  #RewritelogLevel 9 (this is for debugging only)
  #RewriteMap lowercase int:tolower (this is gone, we don't need to deal with HTTP_HOST in 
rewrite condition because it's handled by virtualhost)
  #RewriteCond ${lowercase:%{HTTP_HOST}} ^login\.dev\.myd\.com$
  # if you have a lot of images, add this
  RewriteRule ^/icons/(.+) - [PT,L]
  RewriteRule ^/images/(.+) - [PT,L]
  RewriteCond %{REQUEST_URI} ^/?$ 
  RewriteRule ^(.+) /server/path/to/cgi-bin/login.pl [T=application/x-httpd-cgi,L]
</VirtualHost>

Last edited by freebsd : March 3rd, 2002 at 06:38 AM.

March 4th, 2002, 02:20 AM

pidgin

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hey.
It seems to me like its "little too much" to define a vhost just for functions.
assuming I have/will-have many functions, like submit.dev.myd.com (going to submit.pl), login.dev.myd.com, click.dev.myd.com, signup.dev.myd.com, report.dev.myd.com. each going to his special function.
All I want to do is redirect the "clean" calls (those with only QUERY_STRING - but no REQUEST_URI) to the script while leaving those calls to files (images, scripts, etc... - Tose with non-empty REQUEST_URI) under those aliases free from my intervention.

Isn't it more sensible to do it with mod_rewrite that with vhosts?
maybe it could be done by:

RewriteCond ${lowercase:%{HTTP_HOST}} ^function\.dev\.myd\.com$
RewriteCond %{REQUEST_URI} ??IS_EMPTY??
RewriteRule ^(.+) /server/path/to/cgi-bin/function.pl [T=application/x-httpd-cgi,L]

is there a way to do this ??IS_EMPTY?? thing?
wont it solve my problem efficiently?

BTW:
dont I have to chain the QEURY_STRING to the Rewrited URL? like:
RewriteRule ^(.+) /server/path/to/cgi-bin/function.pl\?%{QUERY_STRING} [T=application/x-httpd-cgi,L]
It somehow works even without - I wonder why?

March 4th, 2002, 03:17 AM

freebsd

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>> It seems to me like its "little too much" to define a vhost just for functions

If you take a close look at your rewrite.log, defining each for a dedicated vhost is not too much, but consumes a lot fewer resource, thus more efficient.

When your RewriteCond ${lowercase:%{HTTP_HOST}} within a <VirtualHost> has too many FQDNs. Even if you only want to match ^function\.dev\.myd\.com$, ^whatever\.dev\.myd\.com$ will still go thru your first condition to match against. When you do the way I suggested previously, you can remove the first condition entirely. Imagine you have a.dev.myd.com to z.dev.myd.com, each request will try to match against your 1st condition, that wastes a lot of resource.

>> is there a way to do this ??IS_EMPTY?? thing?

There is no such thing as an empty REQUEST_URI, it has / at the very least.

>> dont I have to chain the QEURY_STRING to the Rewrited URL?

Yes, but I don't see where QUERY_STRING is coming from when someone requests http://function.dev.myd.com/
You should already know that the default RewriteCond is %{REQUEST_URI}, when you need to switch from that to %{QUERY_STRING}, you need to chain it with [C] so it can carry the rewrite over to the next rule to perform actual rewriting.

March 5th, 2002, 05:22 AM

pidgin

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Hey freebsd.
>> vhost is not too much, but consumes a lot fewer resource, thus more efficient.

makes sense - point taken - done

>> Yes, but I don't see where QUERY_STRING is coming from when someone requests http://function.dev.myd.com/

Its: click.dev.myd.com?123 -> dev.myd.com/cgi-bin/click.pl?123
Thats why the QUERY_STRING (=123) was mentioned.

>> You should already know that the default RewriteCond is %{REQUEST_URI}, when you need to switch from that to %{QUERY_STRING}, you need to chain it with [C] so it can carry the rewrite over to the next rule to perform actual rewriting.

Can you clarify the [C] issue?

>> There is no such thing as an empty REQUEST_URI, it has / at the very least.

What I mean is that / is "empyt".
What I'm doing now (in the login.dev.myd.com vhost) is:
RewriteRule ^/icons/(.+) - [PT,L]
RewriteRule ^/images/(.+) - [PT,L]
RewriteRule ^/cgi-bin/(.+) - [PT,L]
RewriteRule ^(.+) /var/www/cgi-bin/dev.myd.com/login.pl [T=application/x-httpd-cgi,L]
while I only need the login.dev.myd.com to be redirected to /var/www/cgi-bin/dev.myd.com/login.pl i have to state all the preceeding rewrite rules to avoid changind the /icons .images /cgi-bin etc..
is there a way to automatically prevent rewriting of all /[something-that-is-not-empty] so that everything that is http://login.dev.myd.com/*will not be touched while only http://login.dev.myd.com and http://login.dev.myd.com/ will be converted?

#10

March 5th, 2002, 11:16 AM

freebsd

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>> Its: click.dev.myd.com?123 -> dev.myd.com/cgi-bin/click.pl?123

It needs to be click.dev.myd.com/?123 you can't leave out the slash.

>> everything that is http://login.dev.myd.com/*will not be touched

You need at least one RewriteCond such as:

RewriteCond %{REQUEST_URI} !^/[0-9]+$

>> Can you clarify the [C] issue?

You don't need to chain it when there is no HTTP_HOST matching condition.
Here is an example that needs to use [C]:

Code:

RewriteEngine on
RewriteMap      lc              int:tolower
RewriteCond   %{SERVER_NAME}                 ^[^.]+\.domain\.com$ [NC]
RewriteRule   ^/icons/(.+)                  - [PT,L]
RewriteRule   ^(.+)                        %{SERVER_NAME}=$1 [C]
RewriteRule   ^(.*)=(.*)                   ${lc:$1}$2 [C]
RewriteRule   ^([^.]+)\.domain\.com(.*) /var/www/domain.com/$1$2

Like I said, the default condition is to match against REQUEST_URI, in this example, however, I am doing all the rewriting on the SERVER_NAME part, then chain it so my very last rewriterule is doing the REQUEST_URI rewriting. No matter what you do, the final condition must have something to do with REQUEST_URI condition, because that's what Apache sends back to the browser.

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