Dariusz on Software

Do you hate animated ads on web pages? Roll-out whole-page ads that hide main content? Big flash content that will slow down page loading? I do.

Simplest answers for this problem are:

• use text-only browsers (Lynx-like)
• disable JavaScript globally in your browser
• install NoScript Firefox extension

The last option is better if you sometimes need graphics and Flash/Java Script. NoSCript has cute configurable interface:

By default JavaScript / Flash are blocked for all sites (good starting setting), you can enable them by white-listing.

Very useful side-effect of NoScript (except nasty ads removal): your browsing is safer. Only selected domains (whitelisted explicitly) could execute JavaScript in your browser.

I've been using many different Python Web Frameworks so far:

• WebStack + mysqldb + custom template framework (long-term ERP project for small company)
• Django (online shop)
• CherryPy + Cheetah (online PDF design)
• Zope (financial)
• WebStack + SimpleTAL (online PDF design)

All frameworks have its strengths and weakness. For new project that will handle appointments using existing calendar I decided to give web2py a try, rationale:

• all stuff included on board, no manual integration of 3rd party libraries
• stable API
• small and elegant
• integrates with GAE (with subset of DB layer)
• template selection separated from controller (easier unit testing)
• easy template syntax (reuses Python code embedded into markup language)

After first phase of product I'll report if my expectations above were correct and what kind of problems were located (if any).

Web2py is "full stack" Python Web Framework, Lighttpd is fast, multi-threaded HTTP server. I'll present a method to connect web2py-based application under lighttpd.

I assume the following setup is already done:

• A domain named "myapp.com" is configured to point to your server
• Python / lighttpd is already installed on server
• Your web2py app is placed under /var/www/web2py
• Your web2py app has application "myapproot" configured

First of all, you have to configure lighttpd to locate web2py application, create file /etc/lighttpd/conf-enabled/myapp.conf:

$HTTP["host"] =~ "(www\.)?myapp\.com" {
    server.indexfiles = ( "/myapproot" )
    server.document-root = "/var/www/myapp"
    server.dir-listing = "disable"
    fastcgi.server = (
        ".fcgi" => ("localhost" => (
            "check-local" => "disable",
            "min-procs" => "1",
            "max-procs" => "2",
            "socket" => "/tmp/myapp.sock")
        )
    )

    url.rewrite-once = (
        "^/$" => "/ad",
        "^(/.+?/static/.+)$" => "/applications$1",
        "(^|/.*)$" => "/fcgihandler.fcgi$1",
    )
    $HTTP["url"] !~ "^(/ad|/fcgihandler.fcgi|/applications/myapproot/static/)" {
        url.access-deny = ("")
    }
}

Explanation:

• (www\.)?myapp\.com: regular expression to match domain with or without "www." prefix
• server.indexfiles: specifies relative URL that should be called when only domain is given
• server.document-root: specifies location of web2py app in filesystem
• server.dir-listing: we do not want user to list our files using HTTP
• fastcgi.server: specifies where socket file is located
• url.rewrite-once: allow to use elegant (short) URLs
• url.access-deny: files other than static directory should be forbidden (security)

Then you have to configure fcgihandler.fcgi script properly:

(...)
fcgi.WSGIServer(application, bindAddress='/tmp/myapp.sock').run()

Note that /tmp/myapp.sock must be the same as specified in lighttpd configuration.

Then you have to start the fcgihandler.fcgi proces and ensure it will start on every boot. That's all.

SSL is used for (1) encrypting HTTP traffic and for (2) authentication server against browser's database of trusted certificates. Generating SSL certificate properly is important if you want your customer to use https properly. It costs few bugs per year, but your customers won't have any warnings in browser before SSL session (purpose number 2).

However, for internal applications, self-signed certificate may be a sufficient solution (purpose 1 only). You will find below a minimal commands to generate local SSL certificate (accept default values when asked for data on stdin): mkdir -p /etc/lighttpd/ssl/local cd /etc/lighttpd/ssl/local openssl genrsa -passout pass:1234 -des3 -out server.key 1024 openssl req -passin pass:1234 -new -key server.key -out server.csr cp server.key server.key.org openssl rsa -passin pass:1234 -in server.key.org -out server.key openssl x509 -req -in server.csr -signkey server.key -out server.crt cat server.key server.crt > server.pem Then lighttpd installation: $SERVER["socket"] == "<YOUR_IP_ADDRESS>:443" { ssl.engine = "enable" ssl.pemfile = "/etc/lighttpd/ssl/local/server.pem" ssl.ca-file = "/etc/lighttpd/ssl/local/server.crt" } Then you have to accept server certificate in your browser and voila!