How teams scaled Kubernetes: 4 real case studies
4 of the 73 engineering write-ups in our database mention Kubernetes in their stack. They come from 4 companies (Datadog, OpenAI, Shopify and Zalando) and were published between 2020 and 2026. Techniques that show up most often alongside Kubernetes: caching (2). It's often paired with PostgreSQL (2). 3 of the 4 state concrete scale numbers, for example "1 million+ requests/sec moved off shared ingress" (Zalando). Each card below links to our short summary and the original post.
Client-Side Load Balancing at a Million Requests Per Second
Zalando moved the internal fan-out of its Product Read API off the shared Skipper ingress into an in-process JVM load balancer that rebuilds the same xxHash64 consistent-hash ring. They added N-ring fade-in so new pods warm only the products they will keep, bounded load based on occupancy (Little's Law) weighted by latency, and a capped ring walk. Pods ran more evenly, the autoscaler target rose from 50% to 65% CPU, and the fleet shrank by over 25%.
When failover isn't safe: Building high-availability PostgreSQL on Kubernetes
A gameday that injected network latency into one availability zone left several of Datadog's Kubernetes-based PostgreSQL clusters stuck: replicas lagged past Patroni's maximum_lag_on_failover, so no standby could be promoted safely. Datadog moved to a hybrid model: standbys in the leader pool take part in synchronous replication (one synchronous standby, synchronous_mode_strict, synchronous_commit=remote_apply) while read replicas stay asynchronous. pgbench showed remote_apply raised average latency by 53% and cut throughput by 34%, yet production clusters saw no measurable impact after a gradual rollout, and synchronous replication is now enabled in all of its clusters.
Scaling PostgreSQL to power 800 million ChatGPT users
OpenAI runs ChatGPT on a single-primary Postgres with nearly 50 global read replicas. Reads are offloaded, write-heavy shardable workloads move to Cosmos DB, and PgBouncer, cache leasing and multi-layer rate limits keep the primary safe.
Capacity Planning at Scale
How Shopify plans and checks capacity for traffic peaks like BFCM using forecasts and scalability tests.