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3.9. Two Copies of Apache

To illustrate the possibilities, we will run two copies of Apache with different IP addresses on different consoles, as if they were on two completely separate machines. This is not something you want to do often, but for the sake of completeness, here it is. Normally, you would only bother if the different virtual hosts needed very different configurations, such as different values for ServerType, User, TypesConfig, or ServerRoot (none of these directives can apply to a virtual host, since they are global to all servers, which is why you have to run two copies to get the desired effect). If you are expecting a lot of hits, you should try to avoid running more than one copy, as doing so will generally load the machine more.

In our case, we don't have any real need to run two copies; however, we will go this route for the sake of education. You can find the necessary machinery in ... /site.twocopy. There are two subdirectories: customers and sales.

The Config file in ... /customers contains the following:

User webuser
Group webgroup
ServerName www.butterthlies.com
DocumentRoot /usr/www/site.twocopy/customers/htdocs
BindAddress www.butterthlies.com
TransferLog logs/access_log

In ... /sales the Config file is:

User webuser
Group webgroup
ServerName sales.butterthlies.com
DocumentRoot /usr/www/site.twocopy/sales/htdocs
Listen sales-not-vh.butterthlies.com:80
TransferLog logs/access_log

On this occasion, we will exercise the sales-not-vh.butterthlies.com URL. For the first time, we have more than one copy of Apache running, and we have to associate requests on specific URLs with different copies of the server. There are three more directives to do this.

3.9.5. ServerType

ServerType [inetd|standalone]
Default: standalone
Server config

The ServerType directive allows you to control the way in which Apache handles multiple copies of itself. The arguments are inetd or standalone (the default).

inetd

You might not want Apache to spawn a cloud of waiting child processes at all, but to start up a new one each time a request comes in and exit once it has been dealt with. This is slower, but consumes fewer resources when there are no clients to be dealt with. However, this method is deprecated by the Apache Group as being clumsy and inefficient. On some platforms it may not work at all, and the Group has no plans to fix it. The utility inetd is configured in /etc/inetd.conf (see man inetd ). The entry for Apache would look something like this:

http stream tcp nowait root /usr/local/bin/httpd httpd -d directory
standalone

The default; allows the swarm of waiting child servers.

Having set up the customers, we can duplicate the block, making some slight changes to suit the salespeople. The two servers have different DocumentRoots, which is to be expected because that's why we set up two hosts in the first place. They also have different error and transfer logs, but they do not have to. You could have one transfer log and one error log, or you could write all the logging for both sites to a single file.

Type go on the server; while on the client, as before, access http://www.butterthlies.com or http://sales.butterthlies.com/.

The files in ... /sales/htdocs are similar to those on ... /customers/htdocs, but altered enough that we can see the difference when we access the two sites. index.html has been edited so that the first line reads:

<h1>SALESMEN Index to Butterthlies Catalogs</h1>

The file catalog_summer.html has been edited so that it reads:

<h1>Welcome to the great rip-off of '97: Butterthlies Inc</h1>
<p>All our worthless cards are available in packs of 20 at $1.95 a pack.
WHAT A FANTASTIC DISCOUNT! There is an amazing FURTHER 10% discount if you 
order more than 100. </p> ...

and so on, until the joke gets boring. Now we can throw the great machine into operation. From console 1 (on FreeBSD hit ALT-F1), get into ... /customers and type:

% ./go

The first Apache is running. Now get into .../customers and again type:

% ./go

Now, as the client, you log on to http://www.butterthlies.com/ and see the customers' site, which shows you the customers' catalogs. Quit, and metamorphose into a voracious salesperson by logging on to http://sales.butterthlies.com/. You are given a nasty insight into the ugly reality beneath the smiling face of commerce!



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