Serving CGI Scripts With Nginx On Debian Squeeze/Ubuntu 11.04 - Page 2
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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: