100 lines
2.6 KiB
Markdown
100 lines
2.6 KiB
Markdown
---
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title: Glossary
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---
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This document defines the various terms used in etcd documentation, command line and source code.
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## Alarm
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The etcd server raises an alarm whenever the cluster needs operator intervention to remain reliable.
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## Authentication
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Authentication manages user access permissions for etcd resources.
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## Client
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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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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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Compaction discards all etcd event history and superseded keys prior to a given revision.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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## Election
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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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## Endpoint
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A URL pointing to an etcd service or resource.
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## Key
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A user-defined identifier for storing and retrieving user-defined values in etcd.
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## Key range
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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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## Keyspace
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The set of all keys in an etcd cluster.
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## Lease
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A short-lived renewable contract that deletes keys associated with it on its expiry.
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## Member
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A logical etcd server that participates in serving an etcd cluster.
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## Modification Revision
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The first revision to hold the last write to a given key.
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## Peer
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Peer is another member of the same cluster.
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## Proposal
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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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## Quorum
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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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## Revision
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A 64-bit cluster-wide counter that starts at 1 and is incremented each time the keyspace is modified.
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## Role
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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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## Snapshot
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A point-in-time backup of the etcd cluster state.
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## Store
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The physical storage backing the cluster keyspace.
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## Transaction
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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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## Key Version
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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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## Watcher
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A client opens a watcher to observe updates on a given key range.
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