This blog entry documents my recent (successful) attempt to use Simon Urbanek's Rserve and FastRWeb for CGI scripting with R. This is a working blog entry and will be updated or replaced as needed (last updated 4:15 PM 10/6/2011).
#### Helpful documentation:
http://rforge.net/FastRWeb/
http://urbanek.info/research/pub/urbanek-iasc08.pdf
http://www.rforge.net/Rserve/
http://cran.r-project.org/web/packages/Rserve/
(Plus personal communications with Simon, the results
of which are included in the summary below)
#### The steps used (your configuration probably varies):
0. Ubuntu Linux, 64-bit, Version 10.04 LTS (plus updates). I did the following steps as root, but will return to security issues below.
1. I did a fresh installation of the apache2 web server. I noted that the default location of the cgi-bin (used later) is /usr/lib/cgi-bin; yours may vary. I confirmed that this was up and running and that I could use the toy CGI script foo.cgi placed in the cgi-bin:
#!/usr/bin/perl
print "Content-type: text/html\n\n";
print "<html>Hello World</html>";
To test this I pointed my browser to http://localhost/cgi-bin/foo.cgi; if there are problems, consult your system administrator or do detective work (probably in the log files, /var/log/apache2 on my system). Do not continue until you have Hello World working!
2. I did a fresh installation of R, version 2.13.2, using the required --enable-R-shlib option to configure.
3. I installed R packages Rserve, Cairo, FastRWeb, and (though not required) XML (this required installing some libxml2... package in Ubuntu, first, but again is NOT required for Rserve/FastRWeb).
4. After installing FastRWeb, I went into the inst directory of the package and ran the install.sh script; this created /var/FastRWeb, used extensively below.
5. I went into /var/FastRWeb/code and examined the files; in a slightly older version of FastRWeb I commented out a few lines, but the current (10/6/2011) version removed that need for me.
6. I fired up R, and per Simon's instructions did the following:
system.file("cgi-bin", package="FastRWeb")
This revealed the location of a binary called Rcgi. I copied this into /usr/lib/cgi-bin, and renamed it R (instead of Rcgi).
7. Finally, I created a file /var/FastRWeb/web.R/foo.png.R:
# foo.png.R:
run <- function(n=100, ...) {
n <- as.integer(n)
p <- WebPlot(800, 600)
plot(rnorm(n), rnorm(n), pch=19, col=2)
p
}
8. I tested it with the URL: http://localhost/cgi-bin/R/foo.png?n=500
#### Security Issues
I have a feeling that if you have a "trusted machine" without user access, the steps above may not technically pose security risks (even as root); but they do not represent good security practices and *would* introduce security risks on shared servers. For my purposes, I added to the beginning of /var/FastRWeb/code/rserve.conf:
gid 33
uid 33
because www-data (uid and gid 33) is the username for my apache2 instances and it seemed like a reasonable choice. For good measure, I also changed permissions in /var/FastRWeb:
chown www-data:www-data .
chown -R www-data:www-data ./*
Finally, I set
sockmod 0660
umask 0007
based on Simon's recommendation for further security. To stop Rserve and FastRWeb:
killall -INT Rserve
