ETCD监控

Watch key changes

Applications can watch on a key or a range of keys to monitor for any updates.

Here is the command to watch on key foo:

$ etcdctl watch foo

# in another terminal: etcdctl put foo bar

PUT

foo

bar

Here is the command to watch on key foo in hex format:

$ etcdctl watch foo --hex

# in another terminal: etcdctl put foo bar

PUT

\x66\x6f\x6f          # Key

\x62\x61\x72          # Value

Here is the command to watch on a range key from foo to foo9:

$ etcdctl watch foo foo9

# in another terminal: etcdctl put foo bar

PUT

foo

bar

# in another terminal: etcdctl put foo1 bar1

PUT

foo1

bar1

Here is the command to watch on keys having prefix foo:

$ etcdctl watch --prefix foo

# in another terminal: etcdctl put foo bar

PUT

foo

bar

# in another terminal: etcdctl put fooz1 barz1

PUT

fooz1

barz1

Here is the command to watch on multiple keys foo and zoo:

$ etcdctl watch -i

$ watch foo

$ watch zoo

# in another terminal: etcdctl put foo bar

PUT

foo

bar

# in another terminal: etcdctl put zoo val

PUT

zoo

val

监控历史版本变化，为了解决监控期间故障，保证数据更新不会丢失

Suppose we finished the following sequence of operations:

$ etcdctl put foo bar         # revision = 2

OK

$ etcdctl put foo1 bar1       # revision = 3

OK

$ etcdctl put foo bar_new     # revision = 4

OK

$ etcdctl put foo1 bar1_new   # revision = 5

OK

# watch for changes on key `foo` since revision 2

$ etcdctl watch --rev=2 foo

PUT

foo

bar

PUT

foo

bar_new

# watch for changes on key `foo` since revision 3

$ etcdctl watch --rev=3 foo

PUT

foo

bar_new

$ etcdctl watch --prev-kv foo=====最近的修改前和修改后

# in another terminal: etcdctl put foo bar_latest

PUT

foo         # key

bar_new     # last value of foo key before modification

foo         # key

bar_latest  # value of foo key after modification

版本压缩

$ etcdctl compact 5

compacted revision 5

# any revisions before the compacted one are not accessible

$ etcdctl get --rev=4 foo

Error:  rpc error: code = 11 desc = etcdserver: mvcc: required revision has been compacted

授予租约

# grant a lease with 10 second TTL

$ etcdctl lease grant 10

lease 32695410dcc0ca06 granted with TTL(10s)

# attach key foo to lease 32695410dcc0ca06

$ etcdctl put --lease=32695410dcc0ca06 foo bar

OK

Suppose we finished the following sequence of operations:

$ etcdctl lease grant 10

lease 32695410dcc0ca06 granted with TTL(10s)

$ etcdctl put --lease=32695410dcc0ca06 foo bar

OK

取消租约会删除所有附加的KEY

Here is the command to revoke the same lease:

$ etcdctl lease revoke 32695410dcc0ca06

lease 32695410dcc0ca06 revoked

$ etcdctl get foo

# empty response since foo is deleted due to lease revocation

查看租约信息

# grant a lease with 500 second TTL

$ etcdctl lease grant 500

lease 694d5765fc71500b granted with TTL(500s)

# attach key zoo1 to lease 694d5765fc71500b

$ etcdctl put zoo1 val1 --lease=694d5765fc71500b

OK

# attach key zoo2 to lease 694d5765fc71500b

$ etcdctl put zoo2 val2 --lease=694d5765fc71500b

OK

Here is the command to get information about the lease:

$ etcdctl lease timetolive 694d5765fc71500b

lease 694d5765fc71500b granted with TTL(500s), remaining(258s)

Here is the command to get information about the lease along with the keys attached with the lease:

$ etcdctl lease timetolive --keys 694d5765fc71500b

lease 694d5765fc71500b granted with TTL(500s), remaining(132s), attached keys([zoo2 zoo1])

巴特西

ETCD监控

Watch key changes

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