Integrating with Apache (IBM HTTP Server for i)


It is often recommended that you host web applications and APIs behind an HTTP server such as Nginx or Apache. On IBM i, Nginx is available as a PASE RPM. Apache is provided as part of the IBM HTTP Server for i (5770-DG1) product.

The HTTP server can handle many things to help make your application production-ready, for instance:

  • queuing connections when under heavy load

  • Handling TLS. Note that HTTP Server for i integrates with Digital Certificate Manager (DCM), whereas Nginx does not.

  • Filtering various HTTP headers, etc.

  • Handling authentication

  • Serving static content (often more efficiently than a high-level language application server)

  • Handling multiple languages/applications behind a single virtual host

  • Provide logging of HTTP requests

This document offers basic insight into how to tie open source workloads to Apache. It is assumed that you have a basic knowledge of some concepts.

You may also want to consider using Nginx!

Technique # 1: ProxyPass directives

The Apache HTTP server can serve as a simple reverse proxy to any other HTTP server, regardless of how that HTTP server is implemented.

To do this, your httpd.conf needs to load the needed proxy modules. Unlike other platforms, which ship .so files (like, the extensions on IBM i are built in ILE service program form.

LoadModule proxy_module         /QSYS.LIB/QHTTPSVR.LIB/QZSRCORE.SRVPGM
LoadModule proxy_http_module    /QSYS.LIB/QHTTPSVR.LIB/QZSRCORE.SRVPGM
LoadModule proxy_connect_module /QSYS.LIB/QHTTPSVR.LIB/QZSRCORE.SRVPGM

Once those modules are loaded, you can use the ProxyPass and ProxyPassReverse directives to forward the traffic to a backend server. For instance, if you have a Python/Node.js application running on localhost port 8000, you can forward the traffic with these directives:

ProxyPass         / http://localhost:8000/
ProxyPassReverse  / http://localhost:8000/

These directives can also be used for specific paths within the website. For instance, to forward requests from within /site:

ProxyPass         /site/  http://localhost:8000/site/
ProxyPassReverse  /site/  http://localhost:8000/site/

When using this approach, you need to manage the backend job separately from the Apache instance. That is, a STRTCPSVR will not automatically start the backend jobs. Optionally, you can use Service Commander for a more unified experience.

Using a reverse proxy approach is generally best practice for non-PHP languages, because:

  • You can still leverage other open source tools to handle multiple processes if needed. Examples include:

    • pm2

    • uvicorn or hypercorn (Python)

    • gunicorn (Python)

  • You can generally choose any application server or web framework you like. There are many to choose from! Application servers that are optimized for a specific language tend to scale well.

  • It is relatively easy to configure and troubleshoot, even if you have little to no Apache experience.

Technique # 2: FastCGI

FastCGI in Apache is powered by the “Zend enabler.” While originally written to support PHP workloads, it can work for any language that is aware of the FastCGI protocol.

To use FastCGI, first load the Zend enabler module:

LoadModule zend_enabler_module /QSYS.LIB/QHTTPSVR.LIB/QZFAST.SRVPGM

If you’d like to run under a different user ID, you can also use the FastCGIServerID and ServerUserID directives to specify an alternative profile. ServerUserID affects the core Apache operations (for instance, serving static files), and FastCGIServerID affects the processes launched by the Zend enabler.


Next, you will add a <Directory> specification, where you add a type and handler for a particular URL path extension. In this case, I specify that all requests with a .js extension are handled by handler fastcgi-script (the Zend enabler module) with type application/x-httpd-js

<Directory /www/myserver/htdocs/>
  order allow,deny
  allow from all
  AddType application/x-httpd-js .js
  AddHandler fastcgi-script .js

You must also define the type in the Zend enabler modeule by way of the fastcgi.conf configuration file. You must specify Server type and CommandLine. You can also use StartProcesses to start multiple backend jobs. The SetEnv directive is also commonly-used. The IpcDir and IpcPublic directives are also needed for setting the behavior of UNIX Domain sockets

; node.js server
Server type="application/x-httpd-js" CommandLine="/www/myserver/htdocs/node/index.js" StartProcesses="4"  SetEnv="LC_ALL=EN_US.UTF-8" 
; Where to place socket files
IpcDir /www/myserver/logs
IpcPublic *RWX

You will also need to place a proper “shebang” (#!) line at the beginning of your script to run the proper executable. For instance, the first line of your index.js could be #!/QOpenSys/pkgs/bin/node.

With FastCGI, the backend worker jobs are managed by Apache, so STRTCPSVR and ENDTCPSVR commands also start/stop the worker backend jobs as needed.

FastCGI is best practice when using PHP. PHP has a long history with the FastCGI protocol, and they have evolved to work together very well.