A live-sports streaming platform runs its playback control plane on two Kubernetes clusters in two Indian cloud regions, with HLS and DASH delivered through multiple CDNs. The final is forecast at 50 million concurrent viewers, above what two regions can safely carry, so a third region was approved five days before the match. The last time a region was added mid-event, the first ten minutes saw 4 percent video start failures from image pulls, cold caches and 502s from the load balancer.
The interviewer asks“Leadership wants a third region ready to absorb up to 30 percent of new sessions at the innings break of the final, at a moment's notice. Walk me through how you make sure it takes that traffic with zero cold-start impact: what exactly has to be warm, how do you prove it is warm, and how do you move the traffic?”
Cold start is not one thing, so I list every layer that can be cold and warm each one: quotas and reserved capacity days ahead, nodes and real pods running at full target size with consolidation frozen, images baked into the node's data volume, JIT and connection pools warmed with replayed traffic, caches preloaded and kept current from Kafka, and load balancer targets already healthy. I prove it with an automated warmth checklist rather than eyeballing dashboards. Then I shift new sessions only, through the playback API's region assignment rather than DNS, in steps of 1, 5, 15 and 30 percent with automatic gates on start failure and p99. And I rehearse the whole thing on a league match two days before.
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