etcdctl

etcdctl is the command-line client for etcd, a distributed key-value store used to persist configuration data and coordinate services in modern cloud-native environments. The tool is part of the etcd project and is widely used to administer etcd clusters, inspect stored data, and perform operational tasks.

Its commands cover basic data operations such as put, get, and delete, as well as range queries with prefixes. It supports watching keys for changes, transactional operations (txn), and lease management (grant, keep-alive, revoke). Administrative functions include managing users and roles and enabling authentication, along with cluster health and endpoint status checks. It also provides facilities for creating and restoring snapshots.

etcdctl communicates with one or more etcd servers via endpoints specified with the --endpoints flag (for example, https://127.0.0.1:2379). Secure TLS connections can be configured with --cacert, --cert, and --key. To select the API version, set the ETCDCTL_API environment variable (ETCDCTL_API=3 for the current v3 API; ETCDCTL_API=2 for legacy v2). By default, modern releases use v3, but the v2 API remains accessible for older clusters.

Security and authentication: if authentication is enabled on the cluster, credentials must be supplied with the --user flag for each command (for example --user root:password). Other advanced options include using snapshot save and restore, endpoint health checks, and various administrative workflows for managing cluster state.

etcdctl is widely used in Kubernetes and other orchestration platforms where etcd serves as the backing store for configuration data and service discovery.