I
have come up with a way to configure apache
servers across a web farm, (using a single configuration), and
without using mod_macro. All you need to do is to patch the /usr/sbin/apache2ctl
shell script (on Debian) with the following diff:
--- apache2ctl.orig 2006-05-15 00:37:05.793938736 -0500
+++ apache2ctl 2006-05-03
11:53:01.000000000 -0500
@@ -77,11 +77,18 @@
case $ARGV in
start|stop|restart|graceful)
- $HTTPD -k $ARGV
+ $HTTPD -f /etc/apache2.conf
-k $ARGV
ERROR=$?
;;
startssl|sslstart|start-SSL)
- $HTTPD -k start -DSSL
+
+ ### let's create our temp
httpd.conf file (we'll call it apache2.conf for fun ;) )
+ LOCALIP=$(/sbin/ifconfig eth0
| awk '/inet/ { print $2 }' | awk -F ":" '{ print $2 }')
+ cat /etc/apache2/apache2.conf
> /etc/apache2.conf
+ cat
/etc/apache2/sites-enabled/* >> /etc/apache2.conf
+ sed -i "s/IPADDRESS/${LOCALIP}/g"
/etc/apache2.conf
+
+ $HTTPD -f /etc/apache2.conf
-k start -DSSL
ERROR=$?
;;
configtest)
NOTES:
These changes to the /usr/sbin/apache2ctl
shell script essentially generate a new apache httpd.conf file every
time the web server starts or stops. Let me explain these changes and
walk you through each line:
1.
LOCALIP=$(/sbin/ifconfig eth0 | awk '/inet/
{ print $2 }' | awk -F ":" '{ print $2 }')
- This line grabs the ip
address for the local machine and put it into the LOCALIP variable. We
are running all machines off of a single set of configuration files, so
we need to grab the local machines ip address, and will use sed to
replace the placeholder, "IPADDRESS", with the contents of $LOCALIP.
2. cat
/etc/apache2/apache2.conf > /etc/apache2.conf
- Cat the contents of the
/etc/apache2/apache2.conf file into a file named /etc/apache2.conf.
(This file can be named and placed anywhere. We just put it in /etc
because configuration files are often found there). In the Debian
Apache2 package, the /etc/apache2/apache2.conf file contains the global
variables for our Apache configuration. For our purposes, we only need
to change the ip addresses throughout conf file, (and vhost files), so I
removed the ports.conf include directive and moved the contents of the
ports.conf and the NameVirtualHost directives from the vhost conf
files into /etc/apache2/apache2.conf. All instances of ip addresses have
been replaced with a placeholder, "IPADDRESS":
---
oldconf/apache2.conf 2006-01-11 06:23:27.000000000 -0600
+++
apache2.conf 2006-05-05 11:01:50.000000000 -0500
@@
-119,8 +120,13 @@
#
Include all the user configurations:
Include /etc/apache2/httpd.conf
+
#
Include ports listing
-Include /etc/apache2/ports.conf
+#
Include /etc/apache2/ports.conf
+Listen IPADDRESS:80
+Listen IPADDRESS:443
+Listen IPADDRESS:8080
+
#
Include generic snippets of statements
Include /etc/apache2/conf.d/[^.#]*
@@
-389,13 +397,32 @@
#
Allow from .your_domain.com
#</Location>
+NameVirtualHost
IPADDRESS:80
+NameVirtualHost
IPADDRESS:443
+NameVirtualHost
IPADDRESS:8080
#
Include the virtual host configurations:
Include /etc/apache2/sites-enabled/[^.#]*
3.
cat
/etc/apache2/sites-enabled/* >> /etc/apache2.conf
- Next, we append all enabled vhost config files to
the /etc/apache2.conf. This has the advantage of creating a monolithic
Apache conf file, but allows us to manage the server configuration using
the great a2ensite/a2dissite tools that come with the Debian Apache2
package.
4.
sed -i "s/IPADDRESS/${LOCALIP}/g" /etc/apache2.conf
- Finally, we use sed to do a global search and
replace on the /etc/apache2.conf file to replace each instance of "IPADDRESS"
with the ip address of the local machine on which apache is starting.
5. It is important to note that we need to add the new
configuration file to the "stop" case as well:
start|stop|restart|graceful)
- $HTTPD -k $ARGV
+ $HTTPD -f /etc/apache2.conf
-k $ARGV
ERROR=$?
;;
Or else apache will complain about syntax problems in
the /etc/apache2/apache2.conf templates which are used to build the new
/etc/apache2.conf configuration file.
Conclusion
Some of you may be
surprised that I am replacing mod_macro with this new approach, but I
find that this simple shell scripting allows for greater flexibility in
managing the Apache configuration within the confines of the default
Debian Apache2 package, and is much less complex to maintain than
mod_macro. As our configuration file was approaching 2,000-3,000 lines,
we were getting lost within the file and began to make mistakes while
making configuration changes to Apache. This new approach allows us to
move from the monolithic conf file, which is needed by mod_macro, and to
take advantage of the simplicity of a split apache conf file, helping us
to ensure maximum uptime by limiting the possible confusion caused by an
overly-large configuration file.
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