I am using a perl script file as a map file in RewriteMap directive.
As i read the apache load the script once at the beginning, So is it needed to reload or restart apache after any changes to this script file?
Yes, rewrite maps are only registered when Apache is starting. And when using external programs as rewrite maps (i.e. map type pgr) the program files need to be locked with RewriteLock:
This directive sets the filename for a synchronization lockfile which mod_rewrite needs to communicate with RewriteMap programs. Set this lockfile to a local path (not on a NFS-mounted device) when you want to use a rewriting map-program. It is not required for other types of rewriting maps.
But the other map types can be changed afterwards:
For plain text and DBM format files the looked-up keys are cached in-core until the mtime of the mapfile changes or the server does a restart. This way you can have map-functions in rules which are used for every request. This is no problem, because the external lookup only happens once!
I'm not sure if the response above is correct, reload seems to be fine.
You can do "ps aux | grep YOUR_REWRITE_PROGRAM" to check the PID/start time of your rewrite map program.
Apache reload seems to set a new PID/start time for these processes, so I would assume new processes have started, a reload may be fine.
Related
Is it possible to change Apache config file and somehow I can see the change without stopping and starting Apache?
I am talking about Dev/localhost. So, no need to worry about trouble to visitor etc.
(LAMP server configuration)
As a workaround for another problem, I need PHP to be able to access local files, but prevent these files from being served over http by Apache.
Normally, I would just use .htaccess to accomplish this, however due to institutional restrictions, I cannot. I also can't touch php.ini, although I can use php_ini_set within php.
As a creative solution, I thought that if php executes as its own linux user (not as apache) I could use normal chown's and chmod's to accomplish this.
Again, the goal is simply to have a directory of files that apache will not display, but php can access.
I'm open to any suggestions.
Put the files outside of your web accessible root (DocumentRoot), but keep them accessible via PHP.
Suggestion:
/sites
/sites/my.site.com
/sites/my.site.com/data // <-- data goes here
/sites/my.site.com/web // <-- web root is here
Here's a thought. Set the permissions on the files to be inaccessible to even the owner, then when PHP needs them, chmod() then, read them, then chmod() them back to inaccessible.
I have a number of subdomains, which are using crossdomain.xml file and I'm looking to a simple way of managing them all - which get semi-regularly updated. One way I've thought is a PHP script, which pushes and overwrites the xml file. The other, which I much prefer is a an apache redirect on a single file.
So, question is how would I, across multiple domains, redirect an xml on dom1.domain.com and dom2.wirewax.com to the same crossdomain.xml file without Flash getting upset about. i.e. not a 302 HTTP redirect, but internal file fetching.
You can write a PHP script that fetches the content from a single location (database or text file) and sends it as-is to Flash. Yes, the script itself needs to be copied on all hosts.
If you have all websites hosted on same webserver, perhaps mod_alias could help:
Alias /crossdomain.xml /path/to/shared/crossdomain.xml
I have not personally tested this. The reference page includes instructions to setup the shared directory so that it can be read by multiple hosts.
I've taken over development of a fairly heavy-duty LAMP application. The original dev used an .htaccess file with RewriteMap and a PHP script to handle certain conditions of the app.
Specifically, when certain subdomain patterns are requested by the client, the RewriteMap catches them and sends them to the appropriate application module.
I'm quite comfortable with typical mod_rewrite redirects, and I think I've got the basic RewriteMap concept figured out; but I'm struggling to find decent documentation on how RewriteLock works. According to the Apache docs:
This directive sets the filename for a synchronization lockfile which mod_rewrite needs to communicate with RewriteMap programs. Set this lockfile to a local path (not on a NFS-mounted device) when you want to use a rewriting map-program. It is not required for other types of rewriting maps.
But this is still a little vague for me. Whats the exact purpose and function of RewriteLock and how does it work?
RewriteLock is used with the prg: keyword. RewriteMap can be used with several keywords, to use text files (txt:), hashfiles (dbm:), randomized text (rnd:) or external mapping scripts ( this one is the prg: keyword ). In this mode the external script is launched when apache start. Then for every incoming request, when mod-rewrite is calling the prg: mapping, apache sends input to that script and reads the output stream to get the value.
RewriteLock must be used in that case to prevent parallel requests (so parallel inputs to that external process) to mix answers on this process standard output. It's a locking mechanism (a file, the given path, which is a classical token, only one user) to enforce serialization of the calls to this external mapping script. IMHO it should be transparently applied by mod-rewrite when using prg: as I never found a prg case where this locking thing is not mandatory.
Edit:
Well in fact you could use an external prg: without the rewriteLock if randomization of the output is not a problem, i.e. for a given entry you can get a response which was given for another entry, like in a script doing some advanced rnd:, your own round-robin service. But if the output must reflect the entry, then you need that semaphore, which of course can slow down the rewritemap process.
So if you're only using the hashmap or textmap you do not need to set the RewriteLock.
Edit:
You may find useful details on this thread, like the fact the lock file exists only for a few milliseconds, when apache calls the prg and waits for an answer.
Edit:
On the question one strange fact is:
The original dev used an .htaccess file with RewriteMap
This is strange because RewriteMap cannot work on .htaccess files, .htaccess are configuration entries read dynamically and RewriteMap as stated here in the Context line can only be set in the main configuration or in a VirtualHost configuration. It cannot be in a Location, a Directory or a .htaccess. So chances are this will never work in a .htaccess.
Now #puk asked for an example of RewriteMap usage. Well, searching for "RewriteMap" in Stack overflow will show you several real examples:
here in a question
here a list of example in my answer
another here
Apache hangs if you define more than one RewriteLock directives or if you use it in a VHOST config.
The RewriteLock should be specified at server config level and ONLY ONCE. This lock file will be used by all prg type maps. So if you want to use multiple prg maps, I suggest using an internal locking mechanism, for example in PHP there is the flock function, and simply ignore the warning apache writes in the error log.
See here for more info:
http://books.google.com/books?id=HUpTYMf8-aEC&lpg=PP1&pg=PA298#v=onepage&q&f=false
Is there a way to include configuration settings in Apache based on if a directory exists? Basically I have a portable hard drive that I transport between work and home that has some stuff I'm developing on it. I only want the Apache config to load a particular virtual host if the folder exists.
Since Apache 2.4.34 you can now use <IfFile>...</IfFile> which will check to see if a file exists. There's more details on the <IfFile> page.
No, there seems to be no direct way to do this.
The only thing that might be a solution is the IfDefine directive. You can define defines using the -d parameter to when the server is started.
The parameter-name argument is a define as given on the httpd command line via -Dparameter-, at the time the server was started.
You might be able to check for the existence of a directory in a batch or bash file, and set the -d parameter accordingly.
Whether that is an option, will depend on how your server is started from the portable hard drive.
I've come up with a solution that seems to work for Linux and OS X, and it hinges on "mountpoints". It might be possible to emulate it within Windows, as well, but you would probably have to get creative with FUSE and/or Cygwin.
If you create an empty folder in your home directory, such as "/Users/username/ExtraVhosts", you can add an apache directive to "Include /Users/username/ExtraVhosts/*".
Then, when you insert your thumb drive, you can mount somewhere and then use mountpoint "binding" to cross-link the ExtraVhosts folder to a folder on the mobile device.
An OS X example:
I have a thumb drive called 'Cherrybomb'
When I insert it, it always gets mounted to /Volumes/Cherrybomb
I can then use bindfs (sudo port install bindfs) to mount a subfolder of it, like so:
sudo bindfs /Volumes/Cherrybomb/Projects/vhosts /Users/username/ExtraVhosts
Then I can restart apache to read in the updated configuration:
sudo /opt/local/apache2/bin/apachectl restart
At that point, it's just a matter of adding entries in /etc/hosts for server aliases to get picked up.
The linux equivalent would be using the "--bind" parameter of the mount command.
One caveat: This makes it difficult to quickly unmount the USB drive, since it is always marked as "in use" by apache. Here's a removal procedure:
Close all open files and terminal sessions that are using the drive (the present-working-directory in terminal can cause unmount issues)
Stop apache: sudo /opt/local/apache2/bin/apachectl stop
umount /Users/username/ExtraVhosts
Then you can either unmount it graphically or manually (umount /Volumes/Cherrybomb).
If your work and home machines mount the drive to different locations, you could have multiple vhosts folders - home_vhost, work_vhost, etc - and use that in the binding step.
I hope this helps someone out :)
If you point apache to the mountpoint only there shouldn't be an issue. Just don't point Directory directives to directories within the drive.
eg, if you mount /dev/somedisk /mnt/somevhost, the
/mnt/somevhost directory will be there whether or not you have the drive mounted and apache will start. Apache doesn't care if the directory is empty so a <Directory "/mnt/somevhost"/> won't cause server to not start if the drive isn't mounted.
Work with UNIX not against it :-p This solution should be sufficient for development.