How to Configure Multiple Apache Instances based on the default Apache in RHEL 4.6

In my environment, there are requirements to have multiple apache instances in the same servers.

One advantage is of course the obvious economic or ROI sense. Another is easier management from systems administration point of view.

Here, i have summerised the steps used in creating 2 instances using the default apache from RHEL 4.6 64bit

In this example, let me know one apache as websvc1 and another as websvc2.

step 1)
Create 2 copies of the binaries /usr/sbin/httpd

# cp -p /usr/sbin/httpd /usr/sbin/httpd_websvc2

step 2)
Create 2 copies of the apache controller /usr/sbin/apachectl

# cp -p /usr/sbin/apachectl /usr/sbin/apachectl_websvc2

step 3)
Customise the apache controller /usr/sbin/apachectl_websvc2

...
...
# the path to your httpd binary, including options if necessary
HTTPD='/usr/sbin/httpd_websvc2'
...
...
# Source /etc/sysconfig/httpd_websvc2 for $HTTPD setting, etc.
if [ -r /etc/sysconfig/httpd_websvc2 ]; then
. /etc/sysconfig/httpd_websvc2
fi
...
...

Step 4)
Create 2 copies of the apache environment configuration /etc/sysconfig/httpd

# cp -p /etc/sysconfig/httpd /etc/sysconfig/httpd_websvc2

Step 5a)
if you need to source some environment files, say for your site protection or etc, put them in /etc/sysconfig/httpd or /etc/sysconfig/httpd_websvc2

Step 5b)
You need to specify different resources and path for the 2nd and subsequent apache instances, else the 2nd apache to start up will fail. One symptom below if this is not done

- Executing 'service httpd status' shows PID of those httpd_websvc2 as well.

Things to differentiate are not limited to the following,

- pid file
- document root
- lock file
- conf file
- environment source
- etc.

Therefore, edit and append in /etc/sysconfig/httpd_websvc2

...
...
OPTIONS='-f /etc/httpd_websvc2/conf/httpd.conf -DSSL'
PIDFILE=/var/run/httpd_websvc2.pid
LOCKFILE=/var/lock/subsys/httpd_websvc2
CONFFILE=/etc/httpd_websvc2/conf/httpd.conf
...
...


Step 6)
Create 2 copies of service script /etc/init.d/httpd

# cp -p /etc/init.d/httpd /etc/init.d/httpd_websvc2


Step 7)
While setting up this, i noticed the following few scenarios

- Executing 'service httpd stop' when httpd is not running, httpd_websvc2 will be killed as well.
- Executing 'service httpd restart' when httpd is not running, httpd_websvc2 will be killed as well.

Therefore add in /etc/init.d/httpd.

# Add in to check for for HTTPD process presence
checkHttpdPID() {
HTTPDPID=`pidof -o $$ -o $PPID -o %PPID -x /usr/sbin/httpd`
if [ -z "$HTTPDPID" ]; then
echo "/usr/sbin/httpd is not running..."
exit
fi
}
...
...
stop)
checkHttpdPID
stop
;;
status)
checkHttpdPID
status $httpd
RETVAL=$?
;;
restart)
checkHttpdPID
stop
start
;;
...
...

Therefore add in /etc/init.d/httpd_websvc2

...
...
# Add in to check for for HTTPD process presence
checkHttpdPID() {
HTTPDPID=`pidof -o $$ -o $PPID -o %PPID -x /usr/sbin/httpd_websvc2`
if [ -z "$HTTPDPID" ]; then
echo "/usr/sbin/httpd_websvc2 is not running..."
exit
fi
}
...
...
if [ -f /etc/sysconfig/httpd_websvc2 ]; then
. /etc/sysconfig/httpd_websvc2
fi
...
...
apachectl=/usr/sbin/apachectl_websvc2
httpd=${HTTPD-/usr/sbin/httpd_websvc2}
prog=httpd
pidfile=${PIDFILE-/var/run/httpd_websvc2.pid}
lockfile=${LOCKFILE-/var/lock/subsys/httpd_websvc2}
...
...
stop)
checkHttpdPID
stop
;;
status)
checkHttpdPID
status $httpd
RETVAL=$?
;;
restart)
checkHttpdPID
stop
start
;;
...
...

Done.
Commands to use as below.

For websvc1
# service httpd [start/stop/restart/status/configtest]
# apachectl -tS

For websvc2
# service httpd_websvc2 [start/stop/restart/status/configtest]
# apachectl_websvc2 -tS

Thats all.
For configuration of Apache, please refer to your SOP.