man Apache::ConfigFile (3): Parse an Apache style httpd.conf configuration file

SYNOPSIS

#
# Parse the standard Apache httpd.conf
#
use Apache::ConfigFile;
my $ac = Apache::ConfigFile->read("/etc/apache/httpd.conf");
# You can get at individual configuration commands using
# the cmd_config() method:
my $hostname = $ac->cmd_config('ServerName');
my $doc_root = $ac->cmd_config('DocumentRoot');
# Multiple values are returned as a list, meaning that you
# can directly assign them to an array:
my @perlmods = $ac->cmd_config('PerlModule');
# And, you can use the cmd_config_hash() routine to get at
# multiple settings where the first is a type of "key":
my %ftypes = $ac->cmd_config_hash('FileTypeSuffix');
# Then, you can reset the context of the calls using the
# cmd_context() method so that you are accessing the
# appropriate values. For example, if you had a context
# block like
#
# <VirtualHost "10.1.1.2">
# ServerName "www.mydomain.com"
# DocumentRoot "/www/mydomain.com/htdocs"
# </VirtualHost>
#
# You would get to this definition via:
my $vh = $ac->cmd_context(VirtualHost => '10.1.1.2');
my $vhost_server_name = $vh->cmd_config('ServerName');
my $vhost_doc_root = $vh->cmd_config('DocumentRoot');
# If you had multiple VirtualHost declarations for a
# given IP (as would be the case if you're using
# NameVirtualHosts), you could cycle through them with:
for my $vh ($ac->cmd_context(VirtualHost => '10.1.1.3')) {
my $vhost_server_name = $vh->cmd_config('ServerName');
my $vhost_doc_root = $vh->cmd_config('DocumentRoot');
}
# In fact, even better you can "search" for one by specifying
# an additional set of criteria to cmd_config(). To just get
# the VirtualHost "docs.mydomain.com", for example, try:

my $docs_svr = $ac->cmd_context(VirtualHost => '10.1.1.3',
ServerName => 'docs.mydomain.com');
my $docs_base_dir = $docs_svr->cmd_config('DocumentRoot');
# In addition, this module will automatically autoload
# directive-based functions, meaning you can get to
# commonly-used commands by name:
my $host = $ac->server_name;
my $root = $ac->server_root;
my $html = $ac->document_root;
# You also get the mod_perl dir_config() command to get
# at PerlSetVar declarations by name. So, the block:
#
# <Location /myapp>
# SetHandler perl-script
# PerlHandler Apache::MyApp
# PerlSetVar MyAppRoot "/usr/myapp"
# PerlSetVar MyAppRefresh "30m"
# </Location>
#
# Would be accessed as:
my $loc = $ac->cmd_context(Location => '/myapp');
my $app_root = $loc->dir_config('MyAppRoot');
my $app_refr = $loc->dir_config('MyAppRefresh');
# Finally, you get two other utility methods. The first
# will return the current data structure verbatim, and
# the second one will return a dump which you can print
# out or parse or whatever:
my %config = $self->data;
warn "DEBUG: ", $self->dump, "\n";

DESCRIPTION

This module parses the Apache httpd.conf, or any compatible config file, and provides methods for you to access the values from the config file. The above examples show basic usage of this module, which boils down to reading a given config file and then using the "cmd_config()" and "cmd_context()" functions to access its information.

By default, the config file is parsed more or less ``verbatim'', meaning that directives are case-sensitive, variables are not interpolated, and so forth. These features can be changed by options given to the "read()" function (see below).

The "read()" function is the constructor, which reads in a configuration file and returns an object with methods that can be used to access directives from the file. The simplest usage is something like this:

    use Apache::ConfigFile;
    my $ac = Apache::ConfigFile->read("/path/to/httpd.conf");

Which would parse the Apache "httpd.conf" file and give you back an $ac object with the following methods:

cmd_config(): Used to access individual configuration commands
cmd_context(): Used to change the context of the commands you're accessing
dir_config(): Used to access values set via the "PerlSetVar" command (like "mod_perl")

For more examples of standard Apache usage, you should read the ``SYNOPSIS'' above or skip down to the ``FUNCTIONS''.

In addition to reading an Apache config file, this module provides some options that allow the Apache syntax to be extended. This is useful if you're writing your own application and want to use a config file resembling Apache's.

    use Apache::ConfigFile;
    my $ac = Apache::ConfigFile->read(
                    file => "/path/to/httpd.conf",
                    ignore_case  => 1,
                    expand_vars  => 1,
                    fix_booleans => 1
             );

These options would allow us to write a custom config file looking like this:

    BaseDir    "/export"
    ImageDir   "$BaseDir/images"
    BuildDir   "$BaseDir/images"
    <Release "sw7">
        OfficialName "Software Update 7"
        BuildPath "$BuildDir/sw7/REL"         
        Platforms Solaris Linux IRIX HP-UX
        Supported Yes
    </Release>

Then, you would be able to access it as follows:

    use Apache::ConfigFile;
    my $swcfg = Apache::ConfigFile->read("releases.conf");
    # Note that case does not matter
    my $rel = $swcfg->cmd_context(release => 'sw7');
    my $ofn = $rel->cmd_config('bUiLdPaTh');
    
    # This is autoloading + fix_booleans
    unless ($rel->supported) {
        die "Sorry, that release is not supported";
    }

There are several things to note. First, all our "cmd_" functions are now case-insensitive, since we turned on the "ignore_case" flag (which is off by default). Second, notice a couple things about our "unless" statement. Since we specified "fix_booleans", the words ``Yes'', ``True'', and ``On'' will be converted to 1 (true), and ``No'', ``False'', and ``Off'' will become 0 (false). As such, we can use these directives in boolean statements throughout our code.

In addition, since this module provides autoloading so that all config commands are turned into functions, you can access values directly, as shown by the statement "$rel->supported". This statement is equivalent to the longer "$rel->cmd_config('supported')".

Finally, if you just wish to manually navigate the data structure (which is a huge hash of hashes of arrays) without using the accessor functions, you can return the thing verbatim:

    my %conf = $ac->data;
    print "Release is $conf{'release'}\n";

However, note that the internal representation is subject to change, so using the accessor functions is recommended.

FUNCTIONS

read(filename)

read(file => filename, opt => val, opt => val)

The "read()" function reads the configuration file specified and returns an object with methods to access its directives. "read()" has two calling forms. In the simplest version, you just specify a filename, and a new "Apache::ConfigFile" object is returned. Or, if you want to specify options, you specify each one as a key/value pair. For example:

   # keep default options
   my $ac = Apache::ConfigFile->read("httpd.conf");
   # override the case sensitivity and boolean translation
   my $ac = Apache::ConfigFile->read(file => "httpd.conf",
                                     ignore_case  => 1,
                                     fix_booleans => 1);

The list of valid options is:

file

Path to configuration file. If not provided then "/usr/local/apache/conf/httpd.conf" is used by default.

ignore_case

If set to 1, then all directives will be case-insensitive and stored in lowercase. Defaults to 0.

fix_booleans

If set to 1, then the words ``Yes'', ``True'', and ``On'' will be converted to 1 (true), and ``No'', ``False'', and ``Off'' will become 0 (false). This allows you to easily use these types of directives in if statements. Defaults to 0.

expand_vars

If set to 1, then you can reuse variables that you have defined elsewhere in the config file by prefixing them with a "$". For example:

    BaseDir   "/export"
    HomeDir   "$BaseDir/home"

Currently, you can only reuse variables defined at the very top-level. Variables defined within context blocks of any kind cannot be reused.

raise_error

If set to 1, any type of error becomes fatal. Defaults to 0.

cmd_config(directive)

This is the meat-and-potatoes of the module; the method that lets you access configuration directives from your file. Examples:

    my $server_name = $ac->cmd_config('ServerName');
    my $doc_root = $ac->cmd_config('DocumentRoot');

This is a fairly straightforward function. You just give it the name of the directive you wish to access and you get its value back. Each time you call it, you will get the value for the next available instance of that variable. If called in a scalar context, you will just get the first value, assumed to be the ``key''.

What this means is that if you have a config file like this:

    ErrorDocument 404 /errors/404.cgi
    ErrorDocument 500 /errors/500.cgi

To get each line you would use a "while" loop:

    while (my @line = $ac->cmd_config('ErrorDocument')) {
        print "For error $line[0] we're using $line[1]\n";
    }

Which should print:

    For error 404 we're using /errors/404.cgi
    For error 500 we're using /errors/500.cgi

Now, if you just wanted to get the error codes that were being handled, you would still use a "while" loop but in a scalar context:

    while (my $code = $ac->cmd_config('ErrorDocument')) {
        print "We're handling $code\n";
    }

Which should print:

    We're handling 404
    We're handling 500

If you want more flexibility, read the following two functions.

cmd_config_array(directive)

This returns the entire data structure for a given directive as an array of arrays. So, you could get all the "ErrorDocument" configs by saying:

    my @errors = $ac->cmd_config_array('ErrorDocument');

Then, you would have to iterate over these yourself, since each element is an array reference:

    for my $e (@errors) {
        print "Code is $e->[0] and script is $e->[1]\n";
    }

Which should print:

   Code is 404 and script is /errors/404.cgi 
   Code is 500 and script is /errors/500.cgi

Assuming the same configuration as above.

cmd_config_hash(directive)

This is perhaps the most useful form. It returns a set of key/value pairs where the key is the first element and the value is the rest of the line. This is great for handling "FileTypeSuffix" or "AddHandler" lines, for example:

    my %handler = $ac->cmd_config_hash('AddHandler');

This would return a hash where the keys would be the first field, such as "cgi-script" or "server-parsed", and value is the remaining line as an array reference.

As such, you could access a specific one as:

    print "Suffixes for CGI scripts are: @{$handler{cgi-script}}\n";

Which should print out something like this:

    Suffixes for CGI scripts are: .cgi .pl

Note that you had to derefence the value inside of a "@{}" since the value is an array reference. This is so that you can get a list of values reliably. For example:

    my %handler = $ac->cmd_config_hash('AddHandler');
    my @cgi_suffixes   = @{$handler{cgi-script}};
    my @shtml_suffixed = @{$handler{server-parsed}};

That way you get the proper values even in the case of embedded whitespace. In addition, it allows you to define your own complex directives:

    # Format: key "Real Name" option1 option2 option3
    CustomField lname "Last Name" 
    CustomField ctry  "Country" US CA MX JP Other

Then in your code:

    my %custom_field = $ac->cmd_config_hash('CustomField');
    while(my($key, $val) = each %custom_field) {
        my $label = shift(@$val) || ucfirst($key);
        # see if we have any options remaining
        if (@$val) {
            # have options; create select list
            print qq($label: <select name="$key">\n");
            for my $opt (@$val) {
                print qq(<option value="$opt">$opt</option>\n);
            }
            print qq(</select>\n); 
        } else {
            # no options; text field
            print qq($label: <input name="$key" type="text type="text"">\n);
        }
    }

That way you could use an Apache style config file to setup a custom form based application.

cmd_context(context => specification)

You use this command to change the current context of what you are looking at. When you start, you are looking at the very top-level of the config file. However, you may want to look at a specific virtual host or directory. You can do so with this command.

    my $vhost = $ac->cmd_context(VirtualHost => '10.1.1.2');
    my $server_name = $vhost->cmd_config('ServerName');
    my $doc_root    = $vhost->cmd_config('DocumentRoot');

You'll notice that the "cmd_context()" call returns an object will all the same methods, but the data structure now starts from that point down. The context has been altered so that you are looking at the "<VirtualHost "10.1.1.2">". block. As such, any commands that you do will affect that part of the configuration.

In some cases, you may have multiple definitions for a certain context level. One example is "VirtualHost" blocks if you're using "NameVirtualHosts". You have two options. First, you could cycle through all of them in sequence:

    for my $vhost ($ac->cmd_context(VirtualHost => '10.1.1.2')) {
        # ... do stuff ...
    }

However, you may not know what you're looking for. In this case, if you just want to get the ``keys'' of all the "VirtualHost" definitions and then iterate through all of them, you might do something like this:

    my @vhkeys = $ac->cmd_context('VirtualHost');
    for my $vhkey (@vhkeys) {
        my $vhost = $ac->cmd_context(VirtualHost => $vhkey);
    }

Note that this is the one situation where the "cmd_context()" function does not return an object, but rather a list of string keys.

Conversely, you may know exactly which one you're looking for. If so, you can specify one additional ``search'' parameter. For example, if you want the "superfoo" server, you could say:

    my $sf = $ac->cmd_context(VirtualHost => '10.1.1.2',
                              ServerName  => 'superfoo');

And this would look for a context block that looked something like this:

    <VirtualHost "10.1.1.2">
        ServerName "superfoo"
        # ... more config options ...
    </VirtualHost>

you can easily access nested configurations as well. If you had a configuration like this:

    <Location "/upload">
        SetHandler perl-script
        PerlHandler Apache::MyUploadModule
        PerlSetVar MyUploadModuleMaxsize "5M"
        PerlSetVar MyUploadModuleTimeout "300s"
        <Limit>
            require user "bob"
            require user "jim"
        </Limit>
    </Location>

And you wanted to find out what the valid users were who could access this page, you would navigate it like so:

    my $loc = $ac->cmd_context(Location => '/upload');
    my $lim = $loc->cmd_context('Limit');
    my @users = $lim->cmd_config('require');

Or, more succintly:

    my @users = $ac->cmd_context(Location => '/upload')
                   ->cmd_context(Limit => '')->cmd_config('require');

Since "cmd_context()" returns an object pointing to the next context, you can chain calls together to get to a deeply nested level.

dir_config()

This routine is provided for "mod_perl" compatibility. It allows you to access configuration commands specified via the "PerlSetVar" directive. So, assuming the above example, you could access the settings for "MyUploadModule" like so:

    my $upload = $ac->cmd_context(Location => '/upload');
    my $maxsize = $upload->dir_config('MyUploadModuleMaxsize');
    my $timeout = $upload->dir_config('MyUploadModuleTimeout');

The idea is to provide an interface which walks and talks roughly like Apache actually would.

data()

This returns the entire data structure under the current context verabatim. So, you could get all the values for a "VirtualHost" with:

    my $vh = $ac->cmd_context(VirtualHost => '10.1.1.4');
    my %vhost = $vh->data;

If you specified "ignore_case", then all the keys will be lowercase; otherwise, they will be in whatever case they are in the config file.

dump()

This returns a dump of the current data structure in string form. So for debugging purposes you can dump the config with something like this:

    warn "DUMP: ", $ac->dump, "\n";

reread()

You can use this function to reread the configuration file. For example, maybe you want your application to reread its config if it receives a "SIGHUP":

    $SIG{HUP} = \&handler;
    sub handler {
        my $sig = shift;
        if ($sig eq 'HUP') {
            # reread our config file on kill -HUP
            $config->reread;
        }
    }

The above would handle a "SIGHUP" by rereading the config file.

write([file])

This writes the configuration out to disk. If no file is specified, then the one passed to "read()" is used. This method is currently under development and does not work. Patches welcome.

autoloaded calls

In addition to the above, you can also access values by calling a function named for the config command directly:

    my $server_name = $ac->cmd_config('ServerName');

Is the same as:

    my $server_name = $ac->server_name;

Underscores in the function name are taken as a place to put an uppercase letter. So these are all equivalent:

    my $doc_root = $ac->cmd_config('DocumentRoot');
    my $doc_root = $ac->DocumentRoot;   # looks silly
    my $doc_root = $ac->document_root;

Note, though, that the following would not work unless you had set the "ignore_case" option:

    my $doc_root = $ac->documentroot;   # won't work

This is because it will look for the directive "Documentroot", which probably doesn't exist.

ALIASES

When I initially wrote this module, I tried to follow the internal Apache API pretty closely. However, for those unfamiliar with Apache these method names probably make little sense. As such, the following function aliases are provided

directive: Same as "cmd_config()"
directive_array: Same as "cmd_config_array()"
directive_hash: Same as "cmd_config_hash()"
section: Same as "cmd_context()"

So this code:

    my $vh = $ac->cmd_context(VirtualHost => '10.1.1.2');
    my $vhost_server_name = $vh->cmd_config('ServerName');
    my $vhost_doc_root    = $vh->cmd_config('DocumentRoot');
    my %error_handlers    = $ac->cmd_config_hash('ErrorDocument');

Could be rewritten as the following and work exactly the same:

    my $vh = $ac->section(VirtualHost => '10.1.1.2');
    my $vhost_server_name = $vh->directive('ServerName');
    my $vhost_doc_root    = $vh->directive('DocumentRoot');
    my %error_handlers    = $ac->directive_hash('ErrorDocument');

These will always be supported so feel free to use them.

NOTES

Currently "LogFormat" and any other directive with embedded quotes, even if escaped, are not handled correctly. I know there is a fix for it but I have a mental block and can't figure it out. Help!

This module does not mimic the behavior of a live Apache config. In particular, there is no configuration ``inheritance''. This means that subdirectories and virtual hosts do not inherit their defaults from the upper levels of the configuration. This may or may not change in a future version.

Currently, the order of context blocks is not maintained. So, if you define two blocks:

    <Directory "/">
        Options +MultiViews
    </Directory>
    <Directory "/var/apache/htdocs">
        Options +ExecCGI
    </Directory>

There will be no way for you to tell the order in which these were defined. Normally this should not matter, since the idea of a context section is to create a logical entity. However, patches to overcome this limitation are welcomed.

This module has only been tested and used on UNIX platforms. Patches to fix problems with other OSes are welcome.

VERSION

$Id: ConfigFile.pm,v 1.18 2001/09/18 18:31:23 nwiger Exp $

AUTHOR

This module is free software; you may copy this under the terms of the GNU General Public License, or the Artistic License, copies of which should have accompanied your Perl kit.

SYNOPSIS

DESCRIPTION

FUNCTIONS

read(filename)

read(file => filename, opt => val, opt => val)

cmd_config(directive)

cmd_config_array(directive)

cmd_config_hash(directive)

cmd_context(context => specification)

dir_config()

data()

dump()

reread()

write([file])

autoloaded calls

ALIASES

NOTES

VERSION

AUTHOR

LAST SEARCHED