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@@ -2,15 +2,17 @@
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This document defines the various terms used in etcd documentation, command line and source code.
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-## Node
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+## Alarm
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-Node is an instance of raft state machine.
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+The etcd server raises an alarm whenever the cluster needs operator intervention to remain reliable.
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-It has a unique identification, and records other nodes' progress internally when it is the leader.
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+## Authentication
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-## Member
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+Authentication manages user access permissions for etcd resources.
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+
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+## Client
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-Member is an instance of etcd. It hosts a node, and provides service to clients.
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+A client connects to the etcd cluster to issue service requests such as fetching key-value pairs, writing data, or watching for updates.
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## Cluster
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@@ -18,6 +20,42 @@ Cluster consists of several members.
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The node in each member follows raft consensus protocol to replicate logs. Cluster receives proposals from members, commits them and apply to local store.
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+## Compaction
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+
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+Compaction discards all etcd event history and superseded keys prior to a given revision. It is used to reclaim storage space in the etcd backend database.
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+
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+## Election
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+
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+The etcd cluster holds elections among its members to choose a leader as part of the raft consensus protocol.
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+
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+## Endpoint
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+
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+A URL pointing to an etcd service or resource.
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+
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+## Key
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+
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+A user-defined identifier for storing and retrieving user-defined values in etcd.
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+
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+## Key range
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+
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+A set of keys containing either an individual key, a lexical interval for all x such that a < x <= b, or all keys greater than a given key.
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+
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+## Keyspace
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+
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+The set of all keys in an etcd cluster.
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+
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+## Lease
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+
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+A short-lived renewable contract that deletes keys associated with it on its expiry.
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+
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+## Member
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+
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+A logical etcd server that participates in serving an etcd cluster.
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+
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+## Modification Revision
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+
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+The first revision to hold the last write to a given key.
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+
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## Peer
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Peer is another member of the same cluster.
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@@ -26,10 +64,34 @@ Peer is another member of the same cluster.
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A proposal is a request (for example a write request, a configuration change request) that needs to go through raft protocol.
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-## Client
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+## Quorum
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+
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+The number of active members needed for consensus to modify the cluster state. etcd requires a member majority to reach quorum.
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+
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+## Revision
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+
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+A 64-bit cluster-wide counter that is incremented each time the keyspace is modified.
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+
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+## Role
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+
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+A unit of permissions over a set of key ranges which may be granted to a set of users for access control.
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+
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+## Snapshot
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+
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+A point-in-time backup of the etcd cluster state.
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+
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+## Store
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+
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+The physical storage backing the cluster keyspace.
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+
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+## Transaction
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+
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+An atomically executed set of operations. All modified keys in a transaction share the same modification revision.
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+
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+## Key Version
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-Client is a caller of the cluster's HTTP API.
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+The number of writes to a key since it was created, starting at 1. The version of a nonexistent or deleted key is 0.
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-## Machine (deprecated)
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+## Watcher
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-The alternative of Member in etcd before 2.0
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+A client opens a watcher to observe updates on a given key range.
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sharat