Faster Web Applications with SCGI
You need two components: the Python classes for building SCGI applications and a module for your Web server to make it “speak SCGI” to the applications. If you use Red Hat package management (RPM), you can install these using yum install python-scgi apache2-mod_scgi; users of Debian's apt can use apt-get install python-scgi libapache2-mod-scgi.
You also can install either component by hand. The Apache module requires a C compiler and Apache's apxs script. Some distributions keep apxs in a separate development package rather than installing it as part of the regular Apache package.
Assuming you now have those components, next download the source tarball scgi-1.12.tar.gz, and run the commands shown in Listing 1.
Listing 1. Installing SCGI by Hand
# Unpack source directory scgi-1.12 from tarball tar xzf scgi-1.12.tar.gz cd scgi-1.12 # Build the Python part python setup.py build # Install Python module; we'll need root privileges sudo python setup.py install # Now build and install the Apache module cd apache2 sudo make install # Enable the SCGI module in Apache. This may fail, # depending on your Apache version, but no matter. sudo a2enmod scgi # Make Apache's new configuration take effect sudo /etc/init.d/apache2 force-reload
Now, let's make sure it all works. The Python package is a module with some classes, and normally, you'd write your application as a program that imports that module. For debugging, however, you also can run it as a standalone application. When it receives a request from the Web server, it simply prints the request's details as a text page. Perfect for a first test—no coding required!
Find the scgi_server.py module on your system. It should be installed in /usr/lib/python2.4/site-packages/scgi (the 2.4 may be 2.3 or 2.5 on your system). Then, run the module:
cd /usr/lib/python2.4/site-packages/scgi python scgi_server.py
This listens for requests from the Web server on a TCP port on your system, using port 4000 by default. You can make it listen on a different port by passing the desired port number as a command-line argument, such as:
python /usr/lib/python2.4/site-packages/scgi/scgi_server.py 63000
The module keeps running until you kill it, so start it in a separate shell. Remember, you don't need to run an SCGI server as root or even under the Web server's identity.
Now that the SCGI application is waiting for requests, pick a location on your Web site to delegate to the application. Let's say you want it to answer all requests for “/scgitest” on this server. Write an Apache configuration snippet, as shown in Listing 2, to a new file in /etc/apache2/conf.d.
Listing 2. Apache Configuration Snippet
# Load the SCGI module. This is really only needed # if you installed manually and the "a2enmod scgi" # command failed. LoadModule scgi_module /usr/lib/apache2/modules/mod_scgi.so <Location "/scgitest"> # Enable SCGI SCGIHandler On # Other properties for /scgitest, such as access # control # ... </Location> # Hostname and port number where SCGI server for # /scgitest is running. # Port 4000 on localhost (127.0.0.1) is the default. SCGIMount /scgitest 127.0.0.1:4000
The SCGI server doesn't really need to run on the same machine as the Web server, as you can see here. Simply make sure that the SCGI server's port is properly firewalled, so that only your Web server can reach it! That way, your application can be sure that all CGI parameters have been validated by the Web server first. If an attacker could connect directly to your SCGI application, you wouldn't be able to trust that information. The CGI parameter AUTHENTICATED_USER, for instance, tells your application that the request comes from a particular logged-in user. You can believe that only if you hear it from a properly configured Web server.
Make Apache reload its configuration with sudo /etc/init.d/apache2 reload. Your server should now serve a new location, /scgitest, that simply prints your request's CGI parameters when you access it. Verify this by looking it up in a browser. If your server's address is example.org, point your browser at http://example.org/scgitest. You should see a page that looks like Listing 3.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
|CentOS 6.8 Released||May 27, 2016|
|Secure Desktops with Qubes: Introduction||May 27, 2016|
|Chris Birchall's Re-Engineering Legacy Software (Manning Publications)||May 26, 2016|
|ServersCheck's Thermal Imaging Camera Sensor||May 25, 2016|
|Petros Koutoupis' RapidDisk||May 24, 2016|
|The Italian Army Switches to LibreOffice||May 23, 2016|
- Secure Desktops with Qubes: Introduction
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- CentOS 6.8 Released
- Linux Mint 18
- The Italian Army Switches to LibreOffice
- Chris Birchall's Re-Engineering Legacy Software (Manning Publications)
- Petros Koutoupis' RapidDisk
- ServersCheck's Thermal Imaging Camera Sensor
- Oracle vs. Google: Round 2
- The FBI and the Mozilla Foundation Lock Horns over Known Security Hole
Until recently, IBM’s Power Platform was looked upon as being the system that hosted IBM’s flavor of UNIX and proprietary operating system called IBM i. These servers often are found in medium-size businesses running ERP, CRM and financials for on-premise customers. By enabling the Power platform to run the Linux OS, IBM now has positioned Power to be the platform of choice for those already running Linux that are facing scalability issues, especially customers looking at analytics, big data or cloud computing.
￼Running Linux on IBM’s Power hardware offers some obvious benefits, including improved processing speed and memory bandwidth, inherent security, and simpler deployment and management. But if you look beyond the impressive architecture, you’ll also find an open ecosystem that has given rise to a strong, innovative community, as well as an inventory of system and network management applications that really help leverage the benefits offered by running Linux on Power.Get the Guide