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])