Nicolas walks us through a challenging service migration he experienced at Criteo, a personalized retargeting company.

A Windows to Linux server migration was on the way for several months already when they realized that the logging backend they used was not working as expected under Linux and failed to collect metrics. 

Problem: By that time, 95% of the machine park had already switched to Linux.

Product teams relying on those metrics to run their A/B tests were using small data sets subject to noise. As critical metrics, like the  Click-Through Rate, were less abundant, business decisions were more challenging for Nicolas' internal customers.

References

Criteo's blog post Moving .NET to Linux at Scale. 

Clean Code from Robert Martin.

Nicolas' newsletter, Memes Are Eating The World