FCGI_SPAWN(1) User Contributed Perl Documentation FCGI_SPAWN(1)NAMEfcgi_spawn - FastCGI server for CGI-like Perl applications effective
multiprocessing, the executable daemon of FCGI::Spawn
DESCRIPTION
Daemon enables you to launch Perl applications originally written for
CGI environment. To accomplish POST input you should need to patch your
CGI.pm with the patch supplied in the FCGI::Spawn distribution, or the
application, in some rare cases (like the Bugzilla), the both. Daemon
is intended to be launched as a root ( "uid = 0" ) user, although you
may run it as a target user itself. You need the FastCGI-capable web
server capable to work with other ('external') daemons by a FastCGI
protocol: the 'FastCGI requester'. Many features supported like the
fine-tune on the number of processes, maximum number of requests served
by the each process in its lifetime, more on this on FCGI::Spawn, also
tested environments and comparison to the well-known Perl runtime
environments. Main focus of the daemon is the system administration
convinience and adaptation to the OS distribution(s), as it is seen
from:
SYNOPSIS
The necessary configuration for fcgi_spawn is to be located in the
dedicated directory, specified by -c command line parameter (by default
the /usr/local/etc for FreeBSD/Slackware packages; /etc for FHS-
compatible Linux/Cygwin packages ( RedHat, Debian, etc. ) . This
includes the configuration file "fcgi_spawn.conf", and optional preload
scripts aimed similarly as the "startup.pl" of the mod_perl: to preload
the modules before the process to fork, and perform necessary
initialization steps like environment variables setup.
Command line options
Consider all of them to be mandatory:
-c <config_path> Full path to the directory of configuration file, the
fcgi_spawn.conf ( See 'Configuration File' below );
-p <pid_file> Full path and name of the process ID file name;
-l <log_file> Full path and name of the log file name;
-u <user> Name of the system user to run the FastCGI applications;
-g <group> Name of the system group to run the FastCGI applications;
-s <socket> Name of the local UNIX socket to be created by the daemon to
listen for incoming connections. You should try :number or address:number or
host:number as a value of this option in teh case the TCP connectivity is
wanted;
Those are optional:
-e Redefine the exit() Perl builtin function to prevent the
spawned persistent processes from exiting and starting again when your
application(s) exit;
-pl Evaluate the:
Preload Scripts from the configuration directory
You can use preload scripts for modules preload and initialization,
similarly to the what is the apache's "startup.pl" is attended for in
the mod_perl's world , although "fcgi_spawn" doesn't execute them from
the root ( "uid = 0" ) user. ( while apache does ). Typically, good
results are achieved when you try to execute the dummy index page of
the web aplication in them, because it loads the most necessary modules
of the application. If you have no errors when execute that perl script
( obviously "index.pl" or "index.cgi" depending on your application )
as a "fcgi_spawn"'s target user and group ( specified with "-u" and
"-g" options ), you should give it a try. Thing to beware at this point
is: environment variables cause "fcgi_spawn" clears the all of the
environment for security purposes.
Preload scripts are to be located in the configuraion directory with
the names "preload_nonprepared_XX.pl" and "preload_prepared_XX.pl",
respectively. The "XX" here means a number of the execution sequence,
as you may wish to "use SomeModule" on the followed of scripts and have
its functionality on the scripts following after those. The difference
between non- and prepared scripts is: the multi-processing occurs to
happen in between of them ( "prepare" in FCGI::Spawn ). That means that
the 'nonprepared' scripts are the best place to pre-load your
applications' modules, but the handles like the data files, sockets,
database handles, etc. can exist only per single process and therefore
should be established in the 'prepared' scripts.
Predefined symbols for preload scripts are:
$spawn
the FCGI::Spawn object.
It is useful to do the trick like this for your CGI app:
$FCGI::Spawn::fcgi = new CGI;
$spawn->callout( '/path/to/your/CGI/app.pl', $FCGI::Spawn::fcgi );
undef $FCGI::Spawn::fcgi;
( "CGI.pm.patch" supplied in the source package is required for
this to work best. ) This loads the most of your application's code
into memory in the 'nonprepared' script before the daemon to fork()
which is the main to know about what the FCGI::Spawn's prepare is.
CALLED_OUT
the label to go to with the exit() Perl builtin redefined ( '-e'
command line parameter ).
Should be contained in the code reference supplied as a callout
property of the $spawn, the "FCGI::Spawn object". This is to keep
the exit()'ed CGI application from exiting the FastCGI connection
"accept()" loop before "max_requests" processed. The code use this
label like this:
$spawn->{ callout } = sub{ do shift;
CALLED_OUT: eval ' $Bugzilla::_request_cache = { }; '
if defined( $Bugzilla::_request_cache ) and scalar keys %{ $Bugzilla::_request_cache };
};
$OURS
Hash reference to keep scalar variables in between preload eval()s.
Those are to be restored in preload scripts like this:
map{ ${ $main::{ $_ } }
= $OURS->{ $_ } ;
} qw/webguiRoot bugzillaRoot skybillRoot/;
All of the preload scripts, if any exist, are eval()'ed after the
$spawn is initialized with the values from:
Configuration File
"fcgi_spawn.conf", to be read from the configuration directory
specified with "-c" command line parameter, should contain the values
of the FCGI::Spawn object constructor, method "new", if those need to
differ from the defaults. The exception is the "callout" parameter
which is not a constant but the CODE reference and should be set up in
the "preload_noprepared" scripts.
Syntax is: spaces and tabs at the begin of the line are ignored, the
"#" symbol before the rest means this line is ignored as a comment too,
key and value are separated with the space(s) or tab(s) all on the same
line, and if the value is multiple ( same way separated ) values, it is
treated as an array reference ( wanted for "sock_chown" parameter ).
Sample configuration file, "fcgi_spawn.conf.sample", is provided in the
source distribution.
Typical CGI Applications with "fcgi_spawn"
"FCGI::Spawn", and therefore "fcgi_spawn", are able to work in Unix and
Cygwin environments, with 'properly' written CGI applications, which
the most of the well-known CGI applications are. This means: no much
assign of the global variables, incapsulation of the code in the
"Namespace::sub()"s at least, and so on.
Care should be taken about file and database handles closing and
networking sockets disconnection because the "END{}" block of your Perl
application is unlikely to be executed automatically, like it does in
true CGI application. You should refer to Mod_Perl code guides in
Chapter 6 of Practical mod_perl book:
<http://modperlbook.org/pdf/ch06.pdf> Commonly, if your CGI application
runs well with the typical "PerlRun" and "Registry" environments of the
Mod_Perl, it should with the "fcgi_spawn" ( and "CGI.pm.patch" supplied
), too. At least as the examples below do:
WebGUI.org
Till version 6.9 supported CGI mode, requires the 'date' system command
to be present in the PATH. Fix this in preload script. You should
"preload_nonprepared" your "index.pl" with the $spawn's ->callout, too.
Demo is: <http://alpha.vereshagin.org>.
Skybill
Traffic accounting system was rewritten a bit, as you can see from
<http://skybill.sf.net>. It was ( and in many aspects is ) my old dummy
code but it's to show that even that is able to be
"fcgi_spawn"-friendly. You may want to use the "FCGI::Spawn/xinc"
feature not only to cache the XSLT object between request but to share
it among fork()ed processes, it is accomplished with callout of the
index.pl on your "preload_nonprepared" script automatically. Demo is:
<http://skybill.vereshagin.org>.
Bugzilla
Got to know satisfaction: this was probably a worst evil code ever
seen. Despite it has no problems with mod_perl, that required many
tricks to perform and here is the scoop:
Many exit()s on the blocks
Requires the exit() to be redefined with "-e" command line switch
for "fcgi_spawn", and the "CALLED_OUT" label to be crafted like it
is already described here.
CGI.pm ancesting
Requires the both patches to be applied, on "CGI.pm" amd
"Bugzilla/CGI.pm" .
Request caching
Bugzilla's own request cache cleans only if the mod_perl is used
specifically. Same about the "CALLED_OUT" here.
Environment cleaning
As an evil of Date::Manip ( I myself hate it too, since the
"DateTime.pm" infrastructure is much better ), and thus the
WebGUI.org too, the Bugzilla can make your system commands
unavailable from your applications on your PATH environment
variable. This is why you should also enable the "save_env" feature
on "fcgi_spawn.conf", if it is not enabled in FCGI::Spawn by
default.
Also, in some cases the Bugzilla's CGI programs use to take $0
instead of $ENV{ SCRIPT_NAME } which makes the URLs generated
pointless.
Demo is located at:
BUGS And TODOs
<http://bugs.vereshagin.org/product/FCGI%3A%3ASpawn>
Adequate reports are accepted.
Runtime Control
Daemon is supplied with POSIX signal handling: "USR1" makes it to
reopen the log file, and every other signal is passed as is to the
actual FCGI::ProcManager process.
LICENSE
LGPL, as of the MANIFEST file in FCGI::Spawn's CPAN distribution. More
info on fcgi_spawn at: <http://fcgi-spawn.sf.net>.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 92:
'=item' outside of any '=over'
perl v5.20.2 2012-12-07 FCGI_SPAWN(1)
