When using automation and techniques such as feature switching, it is essential to have a good view of your environments so that you know the utilization of all the hardware. Good tooling is important to perform this monitoring, and you want to easily be able to see the vital statistics of every server. This will consist of at least the CPU, memory, and disk space consumption, but it may include more, and you will want alarms set up to alert you if any of these stray outside allowed bands.
The practice of DevOps is the culmination of all of the automation we covered previously with development, operations, and quality-assurance testing teams all collaborating. The only missing pieces left now are to provision and configure infrastructure and then monitor it while in use. Although DevOps is a culture, there is plenty of tooling that can help.