This guide will cover the following mechanisms for bootstrapping an etcd cluster:
* [Static](#static)
* [etcd Discovery](#etcd-discovery)
* [DNS Discovery](#dns-discovery)
[root@node3 ~]# netstat -tunlp|grep etcd
tcp
tcp
tcp
[root@node3 ~]# ls
etcd3.etcd
[root@node3 ~]# ls etcd3.etcd/
fixtures/
member/
[root@node3 ~]# ls etcd3.etcd/fixtures/
client/
peer/
[root@node3 ~]# ls etcd3.etcd/fixtures/peer/
cert.pem
注意:上面的初始化只是在集群初始化时运行一次，之后服务有重启，必须要去除掉initial参数，否则报错
请使用如下类似命令
etcd --name
etcd3
三.管理集群
etcdctl
https://github.com/coreos/etcd/blob/master/Documentation/op-guide/maintenance.md
[root@node3 ~]# etcdctl --version
etcdctl version: 3.0.4
API version: 2
COMMANDS:
集群健康状态
[root@node3 ~]# etcdctl cluster-health
member 2947dd07df9e44da is healthy: got healthy result from http://192.168.8.102:2379
member 571bf93ce7760601 is healthy: got healthy result from http://192.168.8.101:2379
member b200a8bec19bd22e is healthy: got healthy result from http://192.168.8.103:2379
cluster is healthy
集群成员查看
[root@node3 ~]# etcdctl member list
2947dd07df9e44da: name=etcd2 peerURLs=http://192.168.8.102:2380 clientURLs=http://192.168.8.102:2379 isLeader=false
571bf93ce7760601: name=etcd1 peerURLs=http://192.168.8.101:2380 clientURLs=http://192.168.8.101:2379 isLeader=true
b200a8bec19bd22e: name=etcd3 peerURLs=http://192.168.8.103:2380 clientURLs=http://192.168.8.103:2379 isLeader=false
删除集群成员
[root@node2 ~]#
etcdctl member
remove
Removed member 4d11141f72b2744c from cluster
[root@node2 ~]# etcdctl member list
2947dd07df9e44da: name=etcd2 peerURLs=http://192.168.8.102:2380 clientURLs=http://192.168.8.102:2379 isLeader=false
571bf93ce7760601: name=etcd1 peerURLs=http://192.168.8.101:2380 clientURLs=http://192.168.8.101:2379 isLeader=true
添加集群成员
https://github.com/coreos/etcd/blob/master/Documentation/op-guide/runtime-configuration.md
注意:步骤很重要，不然会报集群ID不匹配
[root@node2 ~]# etcdctl member add --help
NAME:
USAGE:
1.将目标节点添加到集群
[root@node2 ~]# etcdctl member add etcd3 http://192.168.8.103:2380
Added member named etcd3 with ID 28e0d98e7ec15cd4 to cluster
ETCD_NAME="etcd3"
ETCD_INITIAL_CLUSTER="etcd3=http://192.168.8.103:2380,etcd2=http://192.168.8.102:2380,etcd1=http://192.168.8.101:2380"
ETCD_INITIAL_CLUSTER_STATE="existing"
[root@node2 ~]# etcdctl member list
2947dd07df9e44da: name=etcd2 peerURLs=http://192.168.8.102:2380 clientURLs=http://192.168.8.102:2379 isLeader=false
571bf93ce7760601: name=etcd1 peerURLs=http://192.168.8.101:2380 clientURLs=http://192.168.8.101:2379 isLeader=true
d4f257d2b5f99b64[unstarted]: peerURLs=http://192.168.8.103:2380
此时，集群会为目标节点生成一个唯一的member ID
2.清空目标节点的data-dir
[root@node3 ~]#rm -rf /opt/etcd
注意:节点删除后，集群中的成员信息会更新，新节点加入集群是作为一个全新的节点加入，如果data-dir有数据，etcd启动时会读取己经存在的数据，启动时仍然用的老member ID,也会造成，集群不无法加入，所以一定要清空新节点的data-dir
2016-08-12 01:59:41.084928 E | rafthttp: failed to find member 2947dd07df9e44da in cluster ce2f2517679629de
2016-08-12 01:59:41.133698 W | rafthttp: failed to process raft message (raft: stopped)
2016-08-12 01:59:41.135746 W | rafthttp: failed to process raft message (raft: stopped)
2016-08-12 01:59:41.170915 E | rafthttp: failed to find member 2947dd07df9e44da in cluster ce2f2517679629de
3.在目标节点上启动etcd
注意: 这里的initial标记一定要指定为existing,如果为new则会自动生成一个新的member ID,和前面添加节点时生成的ID不一致，故日志中会报节点ID不匹配的错
[root@node2 ~]# etcdctl member list
28e0d98e7ec15cd4: name=etcd3 peerURLs=http://192.168.8.103:2380 clientURLs=http://192.168.8.103:2379 isLeader=false
2947dd07df9e44da: name=etcd2 peerURLs=http://192.168.8.102:2380 clientURLs=http://192.168.8.102:2379 isLeader=false
571bf93ce7760601: name=etcd1 peerURLs=http://192.168.8.101:2380 clientURLs=http://192.168.8.101:2379 isLeader=true
如果不通过命令行启动，则"initial-cluster-state": "existing"参数需要写入配置
增删改查
[root@node3 ~]# etcdctl set foo "bar"
bar
[root@node3 ~]# etcdctl get foo
bar
[root@node3 ~]# etcdctl mkdir hello
[root@node3 ~]# etcdctl ls
/foo
/hello
[root@node3 ~]# etcdctl --output extended get foo
Key: /foo
Created-Index: 9
Modified-Index: 9
TTL: 0
Index: 10
bar
[root@node3 ~]# etcdctl --output json get foo
{"action":"get","node":{"key":"/foo","value":"bar","nodes":null,"createdIndex":9,"modifiedIndex":9},"prevNode":null}
[root@node2 ~]# etcdctl update foo "etcd cluster is ok"
etcd cluster is ok
[root@node2 ~]# etcdctl get foo
etcd cluster is ok
[root@node3 ~]#
etcdctl import --snap
/opt/etcd/member/snap/db
starting to import snapshot /opt/etcd/member/snap/db with 10 clients
2016-08-12 01:18:17.281921 I | entering dir: /
finished importing 0 keys
REST API
https://github.com/coreos/etcd/tree/master/Documentation/learning
https://coreos.com/etcd/docs/latest/v2/api.html
[root@node1 ~]# curl 192.168.8.101:2379/v2/keys
{"action":"get","node":{"dir":true,"nodes":[{"key":"/foo","value":"etcd cluster is ok","modifiedIndex":28,"createdIndex":9},{"key":"/hello","dir":true,"modifiedIndex":10,"createdIndex":10},{"key":"/registry","dir":true,"modifiedIndex":47,"createdIndex":47}]}}
[root@node1 ~]# curl -fs -X PUT 192.168.8.101:2379/v2/keys/_test
{"action":"set","node":{"key":"/_test","value":"","modifiedIndex":1439,"createdIndex":1439}}
[root@node1 ~]# curl -X GET 192.168.8.101:2379/v2/keys/_test
{"action":"get","node":{"key":"/_test","value":"","modifiedIndex":1439,"createdIndex":1439}}
curl http://127.0.0.1:2379/v2/members|python -m json.tool
四.systemd管控
1.建用户etcd
useradd -r -s /sbin/nologin etcd
mkdir /opt/etcd
chown -R etcd: /opt/etcd
2.创建systemd服务脚本etcd.service
cat >/lib/systemd/system/etcd.service <<HERE
[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target
[Service]
Type=notify
WorkingDirectory=/opt/etcd/
User=etcd
ExecStart=/usr/local/bin/etcd --config-file /etc/etcd.conf
Restart=on-failure
LimitNOFILE=1000000
[Install]
WantedBy=multi-user.target
HERE
3.创建主配置文件etcd.conf
cat >/etc/etcd.conf <<HERE
name: default
data-dir: "/opt/etcd"
listen-peer-urls: "http://192.168.8.102:2380"
listen-client-urls: "http://192.168.8.102:2379,http://127.0.0.1:2379"
advertise-client-urls: "http://192.168.8.102:2379"
HERE
提示:etcd-3.x版本支持yaml和json两种配置文件格式，配置模板见https://github.com/coreos/etcd/blob/master/etcd.conf.yml.sample
不同节点的配置文件不同，如上是etcd2的范本
4.测试systemd启动
[root@node2 ~]# systemctl enable etcd
Created symlink from /etc/systemd/system/multi-user.target.wants/etcd.service to /usr/lib/systemd/system/etcd.service.
[root@node2 ~]# systemctl start etcd
[root@node2 ~]# systemctl status etcd
● etcd.service - Etcd Server
8月 12 03:10:30 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:11:00 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:11:30 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:12:00 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:12:30 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:13:00 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:13:30 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:14:00 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:14:30 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
8月 12 03:15:00 node2.example.com etcd[12099]: the clock difference against peer 571bf93ce776...1s]
Hint: Some lines were ellipsized, use -l to show in full.