Category Archives: Software

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I am not a big fan of Facebook’s Pavlovification of life, and I try and spend as little time as possible on it. This, unfortunately, has lead to me missing invites to things.

I was shooting the shit with a mate of mine recently, who is even more anti-Facebook, and here’s what I came up with.

iCal Feeds

One of the hidden features Facebook has is that it’s feed of events you’re going to or have been invited to, is made available via an iCal feed you can subscribe to. I had already added this to my Google calendar (add another calendar by URL), so I get a list of upcoming events appearing in my calendar, and you can even tell Google calendar to send you a notification email when new stuff is added.

However, Google has its own problems, so I thought it’d be nice to get a weekly email digest of upcoming things.

Python lists

So, using the python-icalendar module, I wrote a very quick bit of python program that you an point at an ical feed, and get a summary list of upcoming events printed to the console in a nice list. It uses the summary text of the event, together with the start and end times, and, if available, the location and URL link (handy for Facebook events).

It automatically removes events that have already ended, and by default only lists events that start within the next 7 days.

Use it as follows:

python parse_cal.py -u 'https://url.of.feed/ical' -d *numberofdays*

Which outputs something like:

 * Church Of The Heavy presents ECHO4FOUR...VIOLENCE IS GOLDEN...NO DICE GRANDMA...INFURIOUS
     2016-02-24 19:30 - 2016-02-24 22:30
     Wheatsheaf Oxford
     http://www.facebook.com/events/468321193354736/
 * THE HIP DROP!
     2016-02-25 20:00 - 2016-02-26 01:00
     The Bullingdon  (Oxford)
     http://www.facebook.com/events/141392559560311/

Which are two awesome events I’m heading to in the next few weeks (two very different styles of music!)

Now the email

Getting a weekly digest then is just a matter of a bit of cron and mailer goodness, edit your crontab thus:

@weekly /usr/bin/python /path/to/parse_cal.py -u 'https://feed.example.com/calendar.ics' -d 7 | mail -E -s "This week's upcoming events" you@example.com

The program only outputs something if it finds things, so the -E tells mailx to not send anything if there’s no message body.

And you’re done!

I’ve found this pretty handy for a few other calendar feeds (my work joblist for example). Enjoy!

» Visit the project on Github...

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PHP 7 is now out, and Travis-CI supports it as part of their standard configuration (rather than forcing you to use the PHP nightly build). Last night I submitted a pull request to add PHP 7 support to the Known Travis build, which was a little bit problematic.

Known uses Apache + PHP-FPM, rather than the Travis default nginx setup, and while there are guides for getting this working on the Travis site, it seems that they’re not quite there for the PHP 7 build.

The PHP 7 build was running into this error:

[15-Feb-2016 23:14:58] WARNING: Nothing matches the include pattern '/home/travis/.phpenv/versions/7.0.3/etc/php-fpm.d/*.conf' from /home/travis/.phpenv/versions/7.0.3/etc/php-fpm.conf at line 125.
[15-Feb-2016 23:14:58] ERROR: No pool defined. at least one pool section must be specified in config file
[15-Feb-2016 23:14:58] ERROR: failed to post process the configuration
[15-Feb-2016 23:14:58] ERROR: FPM initialization failed
/home/travis/build.sh: line 45: 25862 Segmentation fault      (core dumped) ~/.phpenv/versions/$(phpenv version-name)/sbin/php-fpm

This took a little while to diagnose, but in the end the fix was pretty simple. Basically it looks like the Travis PHP7 build of PHP-FPM expects, but can not find, a pool definition. You don’t need to customise it, just put a default one into PHP-FPM’s config directory.

So, I packaged a default template with the Known patch, and in my .travis.yml added the following to before_script:

- if [[ ${TRAVIS_PHP_VERSION:0:3} == "7.0" ]]; then sudo cp Tests/build/www.conf ~/.phpenv/versions/$(phpenv version-name)/etc/php-fpm.d/; fi

I also modified the Apache vhost example and added ServerName localhost to the definition (although this might not be needed).

After this, the build completes successfully.

PHP7 is new, so I suspect Travis will fix this shortly. However, hopefully this will prevent some hair-pulling in the mean time!

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So, it’s been a frustrating few days debugging a supposedly simple single sign-on handshake conducted over SAML.

Further to my last post, here are a couple of gotchas that tripped me up.

Watch your session settings

If you’re using sessions, you need to make damn sure your cookie settings are the same in both your app and SimpleSAML’s config.php.

Sadly, this isn’t always possible, at least not without making an offering to the Elder Gods. SimpleSAMLPHP’s settings are fiddly, and in the time I was poking at it, I couldn’t find a way of getting it to entirely match the application’s more enhanced security settings (we, for example, stipulate various ini flags and up the session’s hash algorithm).

SimpleSAMLPHP also seems to have a habit of generating its own session ids, although I might have been blinking at the source too long.

Either way, I ended up commenting out the session initialisation code in SessionHandlerPHP::__construct() and replacing every instance of the session starting code with a call to the app’s session initialisation code.

This adds some maintenance debt, but life is too short.

Debug in incognito mode

If you’ve been banging your head against session problems for long, you’ll have a lot of cruft in your cookie jar.

A hard learnt lesson (obvious in hindsight) was that even if the code works, it’ll likely fail with our old friend Exception: The POST data we should restore was lost.

The simplest way of ensuring you’re going to be clicking through with a fresh session is to use your browser’s incognito mode to test, and after each test shut down all of these windows (they share a context, so you’ve got to close all tabs and windows to fully clear the context) and open a new one.

Hopefully this might save you some time and frustration.