go任務排程4（etcd安裝和基本使用）
下載，解壓，進入目錄，執行：
[root@bogon etcd-v3.3.12-linux-amd64]# ./etcd --listen-client-urls 'http://0.0.0.0:2379 ' --advertise-client-urls 'http://0.0.0.0:2379 '
(本地etcd的埠)
etcd控制工具：
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl
(前面需要一個環境變數ETCDCTL_API=3)
put、get、del、--prefix：
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl put "name" "張三"
OK
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "name"
name
張三
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl del "name"
1
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "name"
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl put "/cron/jobs/job1" "{...json}"
OK
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl put "/cron/jobs/job2" "{...json}"
OK
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "/cron/jobs/job2"
/cron/jobs/job2
{...json}
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "/cron/jobs/job1"
/cron/jobs/job1
{...json}
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl get "/cron/jobs/" --prefix
/cron/jobs/job1
{...json}
/cron/jobs/job2
{...json}
[root@bogon etcd-v3.3.12-linux-amd64]#
(帶上--prefix表示get以/cron/jobs/開頭的)
watch監聽k-v的變化：
[root@bogon etcd-v3.3.12-linux-amd64]# ETCDCTL_API=3 ./etcdctl watch "/cron/jobs/" --prefix
PUT
/cron/jobs/job2
{...changed}
DELETE
/cron/jobs/job2
(如果watch後，其他視窗改變/刪除等/cron/jobs/job2的值，會顯示出來。etcd很適合做配置的分發，可以實時感受到變化)