Well, I have just found something interesting while reading
through Pro Apache 3rd edition, by Peter Wainwright.
Apparently, using mod_perl, you can use the full power of
the pearl interpreter INSIDE httpd.conf.
Quote from the book page 449:
"Embedded Perl appears in Apache's configuration inside a
<Perl>...</Perl> container, also known as a Perl section.
Anything inside this container is executed by mod_perl when
Apache starts. You specify configuration directives simply
by assigning a package variable of the same name. For
example;
<Perl>
$ServerAdmin="webmaster@xxxxxxxxxxxxxxxxx";
</Perl>
In Perl, this is a basic assignment of a string to a scalar
variable. In a Perl section, it becomes a configuration
directive because the variable corresponds to the name of a
configuration directive understood by Apache."
Peter Wainwright also provides some very capable examples
in his book, using this technique.
One example of this starts with:
...
#Now write the Perl script and embed it into httpd.conf in
# a <Perl> container
<Perl>
# generate virtual hosts on the fly with Perl
...
...
...
# back to httpd.conf
</Perl>
# ...rest of httpd.conf...
and,
<Perl>
# note the following line calls an external perl interpreter
#!/usr/bin/perl -w
# rest of Perl script - embedded in htpd.conf
# back to httpd.conf
<Perl>
#rest of httpd.conf file
He concludes this section of the chapter by stating,
"Of course you could use any scripting language to create a
configuration file this way because Apache no longer needs
to know how to interpret it (ie the script) itself."
So, in theory (please see disclaimer below - LOL) it should
be possible to use an external php interpreter to generate
httpd.conf files and configuration directives this way, by
embedding the call to the php interpreter into a
<Perl>...</Perl> section.
The above was extracted from the full sample chapter 7,
'Hosting more than one website', available for download from
Apress's website, at:
http://www.apress.com/book/supplementDownload.html?bID=275&sID=2134
The download link is not underlined, and is the text
'Download Sample Chapter' which just looks like a
sub-heading to me.
Pro Apache, Third Edition
Download Sample Chapter <--
This is an excellent book, packed with practical
explanations of how to master Apache. I have struggled with
the online documentation for years. I cannot recommend this
book highly enough!
HTH
Keith
In theory, theory and practice are the same;
In practice they are not.
On Thu, 19 Jan 2006 httpd2@xxxxxxxxxxxx wrote:
> To: users@xxxxxxxxxxxxxxxx
> From: httpd2@xxxxxxxxxxxx
> Subject: Re: [users@httpd] Using environment variable in httpd.conf
>
>
> Thanks for the info Joshua.
>
> I was just curious to know if it was possible to set
> variables in httpd.conf . Probably won't need to
> use such a feature at the moment.
>
> Keith
>
>
> In theory, theory and practice are the same;
> In practice they are not.
>
> On Thu, 19 Jan 2006, Joshua Slive wrote:
>
> > To: users@xxxxxxxxxxxxxxxx
> > From: Joshua Slive <joshua@xxxxxxxx>
> > Subject: Re: [users@httpd] Using environment variable in httpd.conf
> >
> > On 1/19/06, httpd2@xxxxxxxxxxxx <httpd2@xxxxxxxxxxxx> wrote:
> > >
> > > Well Tom, I'm using apache 2.0.50 under SuSE 9.2 pro and
> > > just added the following to httpd.conf, after my LoadModule statements:
> > >
> > > SetEnv ErrLogPath /var/log/apache2/error_log
> > > ErrorLog ${ErrLogPath}
> > > LogLevel debug
> > >
> > > All this does for my setup is create an error_log file under
> > > /srv/www/ called ${ErrLogPath}.
> > >
> > > Am I missing something?
> >
> > The undocumented env-variable-in-config-file feature looks at
> > variables in the server environment at time of startup. SetEnv
> > doesn't actually make real environment variables until a cgi script is
> > launched. See:
> > http://httpd.apache.org/docs/2.2/env.html
> >
> > What you want sounds more like the features provided by mod_macro.
> > See http://modules.apache.org/.
> >
> > But the standard advice in cases like this is: httpd.conf is not a
> > programming language, it is a config file. If you need more advanced
> > features, then use your favorite preprocess (m4, etc) to generate your
> > config files.
> >
> > Joshua.
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