What is the role of etcd in Kubernetes?
etcd is the consistent key-value store that holds the entire desired and observed state of the cluster. Only the API server talks to it. Every other component reads and writes state through the API server, which is why losing etcd without a backup means losing the cluster's brain.
Answered in
What Really Happens After kubectl applyFollow one Deployment from kubectl apply to a running pod: API server, etcd, controllers, scheduler and kubelet each own one step of the chain.
Read the full analysisOther questions this article answers
More system design & architecture questions
- What is a Backend for Frontend?
- What is the main risk of the BFF pattern?
- What is a value-added service layer?
- What does a field mask do in an API?
- What is a cold cache problem?
- How does change data capture keep a cache correct?
- Why use add instead of set when warming a cache?
- Why partition the cache differently from the database?
Every answer on Crashtech is written by the editor of the article it comes from — never auto-summarised. Browse all answers or the System Design & Architecture beat.