etcd之etcd API(二)

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于 2024-09-23 09:16:08 发布

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分类专栏： golang 文章标签： etcd golang

本文链接：https://blog.youkuaiyun.com/qq_30614345/article/details/142316491

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1、etcd API

etcdctl用于与etcd交互的控制台程序。API版本可以通过ETCDCTL_API环境变量设置为2或3版本。默认情况

下，v3.4以上的etcdctl使用v3 API，v3.3及更早的版本默认使用v2 API。

注意：用v2 API创建的任何key将不能通过v3 API查询。同样，用v3 API创建的任何key将不能通过

v2 API查询。

1.1 启动服务

输入命令etcd，即可启动一个单节点的etcd服务，ctrl+c即可停止服务。

运行etcd，在终端输入etcd。

[root@zsx ~]# etcd
{"level":"info","ts":"2023-02-13T13:39:49.847+0800","caller":"etcdmain/etcd.go:73","msg":"Running: ","args":["etcd"]}
{"level":"warn","ts":"2023-02-13T13:39:49.847+0800","caller":"etcdmain/etcd.go:105","msg":"'data-dir' was empty; using default","data-dir":"default.etcd"}
{"level":"info","ts":"2023-02-13T13:39:49.848+0800","caller":"embed/etcd.go:124","msg":"configuring peer listeners","listen-peer-urls":["http://localhost:2380"]}
{"level":"info","ts":"2023-02-13T13:39:49.850+0800","caller":"embed/etcd.go:132","msg":"configuring client listeners","listen-client-urls":["http://localhost:2379"]}
{"level":"info","ts":"2023-02-13T13:39:49.850+0800","caller":"embed/etcd.go:306","msg":"starting an etcd server","etcd-version":"3.5.5","git-sha":"19002cfc6","go-version":"go1.16.15","go-os":"linux","go-arch":"amd64","max-cpu-set":1,"max-cpu-available":1,"member-initialized":false,"name":"default","data-dir":"default.etcd","wal-dir":"","wal-dir-dedicated":"","member-dir":"default.etcd/member","force-new-cluster":false,"heartbeat-interval":"100ms","election-timeout":"1s","initial-election-tick-advance":true,"snapshot-count":100000,"snapshot-catchup-entries":5000,"initial-advertise-peer-urls":["http://localhost:2380"],"listen-peer-urls":["http://localhost:2380"],"advertise-client-urls":["http://localhost:2379"],"listen-client-urls":["http://localhost:2379"],"listen-metrics-urls":[],"cors":["*"],"host-whitelist":["*"],"initial-cluster":"default=http://localhost:2380","initial-cluster-state":"new","initial-cluster-token":"etcd-cluster","quota-backend-bytes":2147483648,"max-request-bytes":1572864,"max-concurrent-streams":4294967295,"pre-vote":true,"initial-corrupt-check":false,"corrupt-check-time-interval":"0s","compact-check-time-enabled":false,"compact-check-time-interval":"1m0s","auto-compaction-mode":"periodic","auto-compaction-retention":"0s","auto-compaction-interval":"0s","discovery-url":"","discovery-proxy":"","downgrade-check-interval":"5s"}
{"level":"info","ts":"2023-02-13T13:39:49.852+0800","caller":"etcdserver/backend.go:81","msg":"opened backend db","path":"default.etcd/member/snap/db","took":"716.361µs"}
......
{"level":"info","ts":"2023-02-13T13:39:50.557+0800","logger":"raft","caller":"etcdserver/zap_raft.go:77","msg":"8e9e05c52164694d became leader at term 2"}
{"level":"info","ts":"2023-02-13T13:39:50.557+0800","logger":"raft","caller":"etcdserver/zap_raft.go:77","msg":"raft.node: 8e9e05c52164694d elected leader 8e9e05c52164694d at term 2"}
......

"name":"default"：name表示节点名称，默认为default。
"data-dir":"default.etcd"：data-dir 保存日志和快照的目录，默认为当前工作目录default.etcd/目录

下。
在http://localhost:2380和集群中其他节点通信。
在http://localhost:2379提供客户端交互。
"heartbeat-interval":"100ms"：heartbeat-interval为100ms，该参数的作用是leader多久发送一次心跳

到followers，默认值是100ms。
"election-timeout":"1s"：election-timeout为1000ms，该参数的作用是重新投票的超时时间，如果

follow在该时间间隔没有收到心跳包，会触发重新投票，默认为1000ms。
"snapshot-count":100000：snapshot-count为10000，该参数的作用是指定有多少事务被提交时，触发截

取快照保存到磁盘。
集群和每个节点都会生成一个uuid。
启动的时候会运行raft，选举出leader。

1.2 查看客户端版本

在另一个终端运行etcdctl version测试。

# 查看默认API版本
[root@zsx ~]# etcdctl version
etcdctl version: 3.5.5
API version: 3.5

1.3 查看帮助文档

[root@zsx ~]# etcdctl -h

etcdctl是一个命令行客户端，可以对etcd服务进行测试或者手动修改数据库内容。另外，etcdctl还支持HTTP

API。 etcdctl支持的命令大体上分为数据库操作和非数据库操作两类。

1.4 写入key

# 写入key
# --sort对结果进行排序
# --consistent将请求发给主节点,保证获取内容的一致性
# etcdctl put /test/foo hello etcd(双引号可去掉)
$ etcdctl put /test/foo "hello etcd" 
OK
$ etcdctl get /test/foo
/test/foo
hello etcd

# 手动切换到v2 API
# set ETCDCTL_API=2
$ export ETCDCTL_API=2
$ etcdctl --version
etcdctl version: 3.5.5
API version: 2

# 查询不到/test/foo的值
$ etcdctl get /test/foo
Error:  client: response is invalid json. The endpoint is probably not valid etcd cluster endpoint

1.5 读取key值

$ etcdctl get /test/foo
/test/foo
hello etcd

# 只是获取值
$ etcdctl get /test/foo --print-value-only
hello etcd

# 获取从foo1到foo3的值,不包括foo3
$ etcdctl put foo1 bar1
$ etcdctl put foo2 bar2
$ etcdctl put foo3 bar3
$ etcdctl get foo1 foo3 --print-value-only 
bar1
bar2

# 获取前缀为foo的值
$ etcdctl get --prefix foo --print-value-only
bar1
bar2
bar3

# 获取符合前缀的前两个值
$ etcdctl get --prefix --limit=2 foo --print-value-only
bar1
bar2

1.6 删除key

# 删除foo1
$ etcdctl del foo1
1

# 删除foo2到foo3，不包括foo3
$ etcdctl del foo2 foo3
1

# 删除key前缀为foo的
# 返回值是删除的个数
$ etcdctl del --prefix foo
1

1.7 监视值变化

# 监视foo单个key
$ etcdctl watch foo

# 另一个控制台执行
$ etcdctl put foo bar
OK

# 第一个控制台输出
PUT
foo
bar

# 同时监视多个值
$ etcdctl watch -i
$ watch foo
$ watch zoo

# 另一个控制台执行
$ etcdctl put foo bar
OK

# 另一个控制台执行
$ etcdctl put zoo val
OK

# 第一个控制台输出
PUT
foo
bar
PUT
zoo
val

# 监视foo前缀的key
$ etcdctl watch --prefix foo

# 另一个控制台执行
$ etcdctl put foo1 bar1
OK

# 另一个控制台执行
$ etcdctl put fooz1 barz1
OK

# 第一个控制台输出
PUT
foo1
bar1
PUT
fooz1
barz1

1.8 设置租约（Grant leases）

当一个key被绑定到一个租约上时，它的生命周期与租约的生命周期绑定。

# 设置60秒后过期时间
# lease grant为命令参数
$ etcdctl lease grant 60
lease 32695410dcc0ca06 granted with TTL(60s)

# 把foo和租约绑定，设置成60秒后过期
$ etcdctl put --lease=32695410dcc0ca06 foo bar
OK

$ etcdctl get foo
foo
bar

# 60秒后，获取不到foo
$ etcdctl get foo
# 返回空

1.9 主动撤销租约（Revoke leases）

通过租赁ID（此处指：32695410dcc0ca06）撤销租约。撤销租约将删除其所有绑定的key。

$ etcdctl lease grant 60
lease 32695410dcc0ca06 granted with TTL(60s)

$ etcdctl put foo bar --lease=32695410dcc0ca06
OK

# 主动撤销租约
$ etcdctl lease revoke 32695410dcc0ca06
lease 32695410dcc0ca06 revoked

$ etcdctl get foo
# 返回空

1.10 续租约（Keep leases alive）

通过刷新其TTL来保持租约的有效，使其不会过期。

# 设置60秒后过期租约
$ etcdctl lease grant 60
lease 32695410dcc0ca06 granted with TTL(60s)

# 把foo和租约绑定，设置成60秒后过期
$ etcdctl put foo bar --lease=32695410dcc0ca06

# 续租约，自动定时执行续租约，续约成功后每次租约为60秒
$ etcdctl lease keep-alive 32695410dcc0ca06
lease 32695410dcc0ca06 keepalived with TTL(60)
lease 32695410dcc0ca06 keepalived with TTL(60)
lease 32695410dcc0ca06 keepalived with TTL(60)
...

1.11 获取租约信息（Get lease information）

获取租约信息，以便续租或查看租约是否仍然存在或已过期

# 设置500秒TTL
$ etcdctl lease grant 500
lease 694d5765fc71500b granted with TTL(500s)

# keyzoo1绑定694d5765fc71500b租约
$ etcdctl put zoo1 val1 --lease=694d5765fc71500b
OK

# 查看租约信息，remaining(132s)剩余有效时间132秒；--keys获取租约绑定的key
$ etcdctl lease timetolive --keys 694d5765fc71500b
lease 694d5765fc71500b granted with TTL(500s), remaining(132s), attached keys([zoo1])

值得注意的地方，一个租约可以绑定多个key

$ etcdctl lease grant 500
lease 694d5765fc71500b granted with TTL(500s)

$ etcdctl put zoo1 val1 --lease=694d5765fc71500b
OK

$ etcdctl put zoo2 val2 --lease=694d5765fc71500b
OK

当租约过期后，所有key值会被删除。

当一个租约只绑定了一个key时，想删除这个key，最好的办法是撤销它的租约，而不是直接删除这个key。

# 方法一: 直接删除key
# 设置租约并绑定zoo1
$ etcdctl lease grant 60
lease 694d71f80ed8bf1e granted with TTL(60s)

$ etcdctl put zoo1 val1 --lease=694d71f80ed8bf1e
OK

# 续租约
$ etcdctl lease keep-alive 694d71f80ed8bf1e
lease 694d71f80ed8bf1e keepalived with TTL(60)

# 另一个控制台执行
$ etcdctl del zoo1

# 单纯删除key后，续约操作还会一直进行，造成内存泄露
lease 694d71f80ed8bf1e keepalived with TTL(60)
lease 694d71f80ed8bf1e keepalived with TTL(60)
lease 694d71f80ed8bf1e keepalived with TTL(60)
...

# 方法二: 撤销key的租约
# 设置租约并绑定zoo1
$ etcdctl lease grant 60
lease 694d71f80ed8bf1e granted with TTL(60s)

$ etcdctl put zoo1 val1 --lease=694d71f80ed8bf1e
OK

# 续租约
$ etcdctl lease keep-alive 694d71f80ed8bf1e
lease 694d71f80ed8bf1e keepalived with TTL(60)
lease 694d71f80ed8bf1e keepalived with TTL(60)

#另一个控制台执行
$ etcdctl lease revoke 694d71f80ed8bf1e
# 续约操作并退出
lease 694d71f80ed8bf1e expired or revoked.