The tooling changes over time, but the operating principles stay surprisingly stable.
Risk
The goal is not zero risk. The goal is an explicit acceptable level.
Measurement
Measure the service as users experience it, not only what is easiest to graph.
Automation
Repeated operational work should become software.
Learning
Incidents must feed better systems, not only blame or hero stories.
Measure what users get, budget the risk, automate the drag, and learn from failure.
That line is a useful one-sentence summary of the whole course.