A Day in the Life of #Apacheby Rich Bowen, coauthor of Apache Cookbook
Author's note: I spend a lot of time on IRC. I mean a lot of time. Time when I really should be doing other things. After all, IRC is a great place to go for answers to questions. The trouble is, everybody seems to ask the same questions, day after day. And the folks that answer the questions tend to get frustrated with the folks asking the questions, and either stop answering, or start flaming. So it occurred to me that I should really start writing up some of these conversations and put them on my web site. About the same time, O'Reilly approached me about writing an article to coincide with the release of Apache Cookbook, which I co-wrote with Ken Coar. I pitched the idea of a series based on my IRC conversations, and voilà, someone is actually going to pay me to do this. Ain't life grand?
Today's piece jump-starts this new series, "A Day in the Life of #Apache", here on ONLamp. The goal of these articles will be to condense some of those frequent IRC conversations into a format that can be used to help folks with these commonly occurring problems, while, at the same time, reducing the burn-out rate of IRC tech support. And, of course, other folks can benefit from these articles without having to put up with the strange and surreal world that is IRC. There will be a Talkback at the end of each of these articles -- please let me know what you think.
Welcome to "day one" on #apache. Today, we encounter a user who is having difficulty getting his .htaccess file working. With the help of Fajita, we'll try to solve this problem. (Fajita is the name of the infobot that runs on the channel.) In future articles, we'll tackle some more difficult problems, but in the first few of this series, we'll look at the problems that seem to come up every day.
#apache is an IRC channel that runs on the
irc.freenode.net IRC network. And, in case you wondered, I'm DrBacchus. (I'm not a real doctor, but I play one on IRC.) To join this channel, you need to install an IRC client (XChat, MIRC, and
bitchx are some of the more popular clients, although there are roughly 3 bazillion other ones, too) and enter the following
/server irc.freenode.net /join #apache
Here's the first snippet of my conversation with this user:
-->b3g1nn3r has joined #apache <b3g1nn3r> Can anybody help me? <DrBacchus> That would depend entirely on the nature of your problem. <b3g1nn3r> Well, I'm using a .htaccess file, and it's not working. <DrBacchus> details? <fajita> You need to give us a few additional details. What, exactly, is happening, and how does this differ from what you expect to be happening?
Perhaps the biggest challenge in troubleshooting Apache problems (or, really, any problem at all) is getting "customers" to clearly state what the problem is that they are experiencing. Most of the time, once we can persuade them to tell us exactly what is happening, and what they are trying to do, the solution winds up being fairly simple.
<b3g1nn3r> I created a .htaccess file and put some directives in it, but when I load pages from that directory, it appears that the .htaccess file is being ignored. <DrBacchus> What is AllowOverride set to? <b3g1nn3r> AllowOverride None <fajita> AllowOverride None means "Please ignore my htaccess files."
AllowOverride directive controls the use of
.htaccess files. These are
files that permit users who don't have access to the main server-configuration file to override the configuration settings on the
server for particular directories.
Since many server admins don't want users to override
this configuration, the default Apache configuration file does
not permit .htaccess files. Or, stated differently,
we want server admins to have to make the conscious choice to
permit this feature, rather than having it enabled by default.
And so the default configuration file contains
AllowOverride None for most scopes, as Fajita
<b3g1nn3r> So what should I have it set to? <DrBacchus> That depends on what you are putting in your .htaccess file.
AllowOverride is not simply turned on or off.
Rather, Apache configuration directives fall into a number of
broad categories, and
AllowOverride allows you to
permit, or not permit, these categories of directives in
Here are those categories, and what they mean:
||Directives related to authentication, such as
||Directives about the file type, such as MIME type (e.g.,
||Directives relating to automatic directory listings, such
||Directives limiting access by host address (i.e.,
||Allows the setting of the
<b3g1nn3r> AllowOverride All? <fajita> AllowOverride All is a really bad idea, because it implies AllowOverride Options, which lets people do stuff like Options FollowSymlinks and Options ExecCGI, even though they are explicitly disabled in the main config.
While Fajita's opinion here is not necessarily the only view
on the matter, it does reflect a common theme in sysadmining.
Namely, only turn on the stuff that you need. There are probably
AllowOverride All is appropriate. But
usually, what you really want to do is determine what is actually
needed, and set
AllowOverride to permit just the
directives you are actually using. For example, if you are
using the .htaccess file just to set a MIME type in
a particular directory, then it is sufficient to set
<b3g1nn3r> So, how do I know what to set AllowOverride to in a given situation? <DrBacchus> You look in the Apache documentation for that particular directive, and see what the
Overridefield says. That's what you have to set
AllowOverrideto in order to permit that directive, and other related directives.
And, of course, some directives aren't allowed in
.htaccess files at all. When considering a
particular directive, there are two things that you should look
for in the documentation. For example, if we look in the docs for
AuthType directive, we see the following:
The two pieces of information we're interested in here
are the Context line, which says that this
directive is permitted in .htaccess files, and the
Override line, which says that
AllowOverride would need to be set to
AuthConfig in order for that to be permitted.
Many directives can't be put in .htaccess files
at all. For example, it wouldn't make much sense to change the
Port of a server on a
<b3g1nn3r> Oh, thanks. Setting AllowOverride to the correct value made my .htaccess file work. Thanks for your help! <-- b3g1nn3r has left #apache
Of course, we never did know what b3g1nn3r was trying to do with his .htaccess file, but, in this particular case, it didn't actually matter.
In summary, here's what we learned:
Apache's default configuration file contains
AllowOverride None, which causes .htaccess files to get ignored.
Each Apache configuration directive has documentation that tells you whether you can put that directive in a
.htaccess file at all, and, if so, what you need to set
AllowOverride in order to permit it.
Stay tuned. Next month we'll tackle another common Apache dilemma.
Rich Bowen is a member of the Apache Software Foundation, working primarily on the documentation for the Apache Web Server. DrBacchus, Rich's handle on IRC, can be found on the web at www.drbacchus.com/journal.
O'Reilly & Associates recently released (November 2003) Apache Cookbook.
Sample Chapter 9, "Error Handling," is available free online.
For more information, or to order the book, click here.
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