Terraform Apply. 500 Students Watching Live. No Safety Net. One Typo Away.

500 students. Live conference demo. Terraform apply with no safety net. One typo and the entire infrastructure crumbles in front of an audience. This is the story of the live infrastructure demo that went sideways - and the lessons I learned about teaching, preparation, and why "Terraform apply" should never be your scariest command. The architecture being deployed live: virtual networks with proper subnet isolation, network security groups enforcing zero-trust rules, private DNS zones so nothing is exposed to the public internet, automated VM provisioning, MySQL behind private endpoints with encryption at rest. Twenty-three resources. All codified. All reproducible. The whole point was to show 500 students that real infrastructure isn't slides with diagrams - it's Terraform, Azure, and deployments you can actually replicate. Then the first apply failed. Network policy conflict. 500 pairs of eyes watching. Two options: pivot to slides and pretend the demo was "supplementary," or debug live with zero guarantee of fixing it. Chose option two. Found the CIDR conflict in 90 seconds. Fixed it. Re-applied. All 23 resources came up green. The applause was louder than it would have…