Several years ago at OpenAI I helped author Scaling Kubernetes to 7500 Nodes which remains one of the CNCF’s most popular blog posts. Alibaba made a post about running Kubernetes clusters with 10K nodes. Google made a post about 15K nodes with Bayer Crop Science. Fast forward to today, GKE supports running some clusters up to 65K nodes, and AWS recently announced support for clusters up to 100K nodes.
