What is etcd
etcd is a key-value store for the most critical data of distributed systems. Use cases include applications running on Container Linux by CoreOS, which enables automatic Linux kernel updates. CoreOS uses etcd to store semaphore values to make sure only subset of cluster are rebooting at any given time. Kubernetes uses etcd to store cluster states for service discovery and cluster management, and it uses watch API to monitor critical configuration changes. Consistency is the key to ensure that services correctly schedule and operate.
Reliability and robustness is etcd’s highest priority. This post will explain how etcd is tested under various failure conditions.
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