3 Using Simple CGI
Another approach is to use a CGI wrapper script, as described here: http://wiki.nginx.org/NginxSimpleCGI
The advantage over Thttpd is that each vhost can have its own cgi-bin directory. The CGI wrapper should work well for simple CGI scripts, but you might get problems with more complex scripts.
Let's install the requirements for the CGI wrapper script:
apt-get install libfcgi-perl libfcgi-procmanager-perl
Now we create the /usr/local/bin/cgiwrap-fcgi.pl wrapper script (the script is taken from http://wiki.nginx.org/NginxSimpleCGI):
vi /usr/local/bin/cgiwrap-fcgi.pl
#!/usr/bin/perl
use FCGI;
use Socket;
use FCGI::ProcManager;
sub shutdown { FCGI::CloseSocket($socket); exit; }
sub restart { FCGI::CloseSocket($socket); &main; }
use sigtrap 'handler', \&shutdown, 'normal-signals';
use sigtrap 'handler', \&restart, 'HUP';
require 'syscall.ph';
use POSIX qw(setsid);
END() { }
BEGIN() { }
{
no warnings;
*CORE::GLOBAL::exit = sub { die "fakeexit\nrc=" . shift() . "\n"; };
};
eval q{exit};
if ($@) {
exit unless $@ =~ /^fakeexit/;
}
&main;
sub daemonize() {
chdir '/' or die "Can't chdir to /: $!";
defined( my $pid = fork ) or die "Can't fork: $!";
exit if $pid;
setsid() or die "Can't start a new session: $!";
umask 0;
}
sub main {
$proc_manager = FCGI::ProcManager->new( {n_processes => 5} );
$socket = FCGI::OpenSocket( "/var/run/nginx/cgiwrap-dispatch.sock", 10 )
; #use UNIX sockets - user running this script must have w access to the 'nginx' folder!!
$request =
FCGI::Request( \*STDIN, \*STDOUT, \*STDERR, \%req_params, $socket,
&FCGI::FAIL_ACCEPT_ON_INTR );
$proc_manager->pm_manage();
if ($request) { request_loop() }
FCGI::CloseSocket($socket);
}
sub request_loop {
while ( $request->Accept() >= 0 ) {
$proc_manager->pm_pre_dispatch();
#processing any STDIN input from WebServer (for CGI-POST actions)
$stdin_passthrough = '';
{ no warnings; $req_len = 0 + $req_params{'CONTENT_LENGTH'}; };
if ( ( $req_params{'REQUEST_METHOD'} eq 'POST' ) && ( $req_len != 0 ) ) {
my $bytes_read = 0;
while ( $bytes_read < $req_len ) {
my $data = '';
my $bytes = read( STDIN, $data, ( $req_len - $bytes_read ) );
last if ( $bytes == 0 || !defined($bytes) );
$stdin_passthrough .= $data;
$bytes_read += $bytes;
}
}
#running the cgi app
if (
( -x $req_params{SCRIPT_FILENAME} ) && #can I execute this?
( -s $req_params{SCRIPT_FILENAME} ) && #Is this file empty?
( -r $req_params{SCRIPT_FILENAME} ) #can I read this file?
) {
pipe( CHILD_RD, PARENT_WR );
pipe( PARENT_ERR, CHILD_ERR );
my $pid = open( CHILD_O, "-|" );
unless ( defined($pid) ) {
print("Content-type: text/plain\r\n\r\n");
print "Error: CGI app returned no output - Executing $req_params{SCRIPT_FILENAME} failed !\n";
next;
}
$oldfh = select(PARENT_ERR);
$| = 1;
select(CHILD_O);
$| = 1;
select($oldfh);
if ( $pid > 0 ) {
close(CHILD_RD);
close(CHILD_ERR);
print PARENT_WR $stdin_passthrough;
close(PARENT_WR);
$rin = $rout = $ein = $eout = '';
vec( $rin, fileno(CHILD_O), 1 ) = 1;
vec( $rin, fileno(PARENT_ERR), 1 ) = 1;
$ein = $rin;
$nfound = 0;
while ( $nfound = select( $rout = $rin, undef, $ein = $eout, 10 ) ) {
die "$!" unless $nfound != -1;
$r1 = vec( $rout, fileno(PARENT_ERR), 1 ) == 1;
$r2 = vec( $rout, fileno(CHILD_O), 1 ) == 1;
$e1 = vec( $eout, fileno(PARENT_ERR), 1 ) == 1;
$e2 = vec( $eout, fileno(CHILD_O), 1 ) == 1;
if ($r1) {
while ( $bytes = read( PARENT_ERR, $errbytes, 4096 ) ) {
print STDERR $errbytes;
}
if ($!) {
$err = $!;
die $!;
vec( $rin, fileno(PARENT_ERR), 1 ) = 0
unless ( $err == EINTR or $err == EAGAIN );
}
}
if ($r2) {
while ( $bytes = read( CHILD_O, $s, 4096 ) ) {
print $s;
}
if ( !defined($bytes) ) {
$err = $!;
die $!;
vec( $rin, fileno(CHILD_O), 1 ) = 0
unless ( $err == EINTR or $err == EAGAIN );
}
}
last if ( $e1 || $e2 );
}
close CHILD_RD;
close PARENT_ERR;
waitpid( $pid, 0 );
} else {
foreach $key ( keys %req_params ) {
$ENV{$key} = $req_params{$key};
}
# cd to the script's local directory
if ( $req_params{SCRIPT_FILENAME} =~ /^(.*)\/[^\/] +$/ ) {
chdir $1;
}
close(PARENT_WR);
#close(PARENT_ERR);
close(STDIN);
close(STDERR);
#fcntl(CHILD_RD, F_DUPFD, 0);
syscall( &SYS_dup2, fileno(CHILD_RD), 0 );
syscall( &SYS_dup2, fileno(CHILD_ERR), 2 );
#open(STDIN, "<&CHILD_RD");
exec( $req_params{SCRIPT_FILENAME} );
die("exec failed");
}
} else {
print("Content-type: text/plain\r\n\r\n");
print "Error: No such CGI app - $req_params{SCRIPT_FILENAME} may not exist or is not executable by this process.\n";
}
}
}
|
Make the script executable...
chmod 755 /usr/local/bin/cgiwrap-fcgi.pl
... and create the /var/run/nginx/ directory where the script will create its socket (that nginx will connect to):
mkdir /var/run/nginx/
By default, nginx runs as the www-data user; nginx must have read and write access to the /var/run/nginx/ directory, therefore we do a chown:
chown www-data:www-data /var/run/nginx/
Because the socket /var/run/nginx/cgiwrap-dispatch.sock (which will be created by the wrapper) must also be owned by www-data, we start the wrapper as the www-data user:
su www-data
/usr/local/bin/cgiwrap-fcgi.pl &> /dev/null &
The wrapper should now run as a daemon in the background, so we can become root again:
exit
Now open your vhost configuration file...
vi /etc/nginx/sites-enabled/www.example.com.vhost
... and add a location /cgi-bin {} section to the server {} container:
server {
[...]
location /cgi-bin {
root /var/www/www.example.com;
gzip off; #gzip makes scripts feel slower since they have to complete before getting gzipped
fastcgi_pass unix:/var/run/nginx/cgiwrap-dispatch.sock;
include /etc/nginx/fastcgi_params;
fastcgi_index index.cgi;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}
[...]
}
|
Reload nginx:
/etc/init.d/nginx reload
Next we create our cgi-bin directory - /var/www/www.example.com/cgi-bin because we defined root /var/www/www.example.com; in the location /cgi-bin {} container:
mkdir /var/www/www.example.com/cgi-bin
Now we place our CGI scripts in it and make them executable. For testing purposes I will create a small Hello World Perl script (instead of hello_world.cgi you can also use the extension .pl -> hello_world.pl):
vi /var/www/www.example.com/cgi-bin/hello_world.cgi
#!/usr/bin/perl -w
# Tell perl to send a html header.
# So your browser gets the output
# rather then <stdout>(command line
# on the server.)
print "Content-type: text/html\n\n";
# print your basic html tags.
# and the content of them.
print "<html><head><title>Hello World!! </title></head>\n";
print "<body><h1>Hello world</h1></body></html>\n";
|
chmod 755 /var/www/www.example.com/cgi-bin/hello_world.cgi
Open a browser and test the script:
http://www.example.com/cgi-bin/hello_world.cgi
If all goes well, you should get the following output: