Time zones in Jekyll on Ruby 2.4

2017/08/21

GitHub Pages upgraded the Ruby interpreter they use to run Jekyll. With that, it started to use the time zone specified by the date variable in each post’s front matter instead of the global timezone variable from the site’s _config.yml file. Prior to GitHub pages making the switch, this change in behavior was reported as a bug in Jekyll.

This change, combined with several other factors, led to most of my posts’ permalinks breaking for a few days.

They're like all off by one day.

It happened to be the case that:

I live far west, with a big “minus” time zone.
I wrote most of the posts in the evening.
The script I used to generate the date variable in the front matter always used UTC for simplicity.
Jekyll (by default?) files post pages into directories for the year, month, and day.

And then all the days in the URL paths changed. What a thing to have happened.

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