Hearing "we don't deploy on Fridays" makes me sad, because I always encounter it as a precautionary measure.
Fear and precaution
The subtext is "it's not safe to deploy" and "if there is a problem, it takes too long to fix".
There is plenty out there about this topic. Search for "deployment on Friday". I almost forgot I've also written about this before. The arguments are more or less the same. If you are afraid to deploy, it may be because:
- you have insufficient monitoring and alerting; or
- the deployment process is error-prone; or
- deployments, and thus rollbacks, are too slow; or
- if something breaks, you don't know how to fix it; or
- risky changes are deployed all at once (vs using feature flags, gradual roll-outs, etc.).
Those are all valid reasons. But they're also valid reasons on a Monday morning. So, do address them.
Valid reasons to not deploy on Fridays
Still, I'd love to hear no-deployment Fridays associated with joy rather than fear.
On a literal level not everyone works on Friday. A Monday-to-Friday workweek is not universal.
That got me thinking: what if the work culture made it so that there is nothing to deploy on Fridays?
We don't deploy on Fridays, because we work a 4-day week and take Friday off (but we do deploy on Thursdays!).
We don't deploy on Fridays, because we contribute to open source.
We don't deploy on Fridays, because we conduct interviews.
We don't deploy on Fridays, because we write blog posts.
We don't deploy on Fridays, because we check and update documentation.
We don't deploy on Fridays, because we work on making our test suite faster.
We don't deploy on Fridays, because the developers all do customer support to get a better understanding about how the product is used.
We don't deploy on Fridays, because Fridays are a dedicated learning day.