etcd 集群管理维护

etcd 集群管理维护

官方网站:

环境:

CentOS7

etcd-3.0.4

3节点集群示例

etcd1:192.168.8.101

etcd2:192.168.8.102

etcd3:192.168.8.103

一.安装etcd(所有节点)

tar xzvf etcd-v3.0.4-linux-amd64.tar.gz

cp -af etcd-v3.0.4-linux-amd64/{etcd,etcdctl} /usr/local/bin

chmod +x /usr/local/bin/{etcd,etcdctl}

二.配置etcd集群

cluster帮助文档etcd-v3.0.4-linux-amd64/Documentation/op-guide/clustering.md

This guide will cover the following mechanisms for bootstrapping an etcd cluster:

* [Static](#static)

* [etcd Discovery](#etcd-discovery)

* [DNS Discovery](#dns-discovery)

目前支持三种发现方式，Static适用于有固定IP的主机节点，etcd Discovery适用于DHCP环境，DNS Discovery依赖DNS SRV记录

Static方式

提示：etcd支持ssl/tls,详见官方文档

节点一:etcd1:192.168.8.101

etcd --name etcd1 --data-dir /opt/etcd \

--initial-cluster-token etcd-cluster-1 \

--initial-cluster-state new

节点二:etcd2:192.168.8.102

etcd --name etcd2 --data-dir /opt/etcd \

--initial-cluster-token etcd-cluster-1 \

--initial-cluster-state new

节点三:etcd1:192.168.8.103

etcd --name etcd3 --data-dir /opt/etcd \

--initial-cluster-token etcd-cluster-1 \

--initial-cluster-state new

2379是用于监听客户端请求，2380用于集群通信，可以通过--data-dir指定数据存放目录，不指定则默认为当前工作目录

[root@node3 ~]# netstat -tunlp|grep etcd

tcp        0      0 192.168.8.103:2379      0.0.0.0:*               LISTEN      11103/etcd

tcp        0      0 127.0.0.1:2379          0.0.0.0:*               LISTEN      11103/etcd

tcp        0      0 192.168.8.103:2380      0.0.0.0:*               LISTEN      11103/etcd

[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  key.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   --data-dir /opt/etcd \

三.管理集群

etcdctl

[root@node3 ~]# etcdctl --version

etcdctl version: 3.0.4

API version: 2

COMMANDS:

backup          backup an etcd directory

cluster-health  check the health of the etcd cluster

mk              make a new key with a given value

mkdir           make a new directory

rm              remove a key or a directory

rmdir           removes the key if it is an empty directory or a key-value pair

get             retrieve the value of a key

ls              retrieve a directory

set             set the value of a key

setdir          create a new directory or update an existing directory TTL

update          update an existing key with a given value

updatedir       update an existing directory

watch           watch a key for changes

exec-watch      watch a key for changes and exec an executable

import          import a snapshot to a cluster

auth            overall auth controls

集群健康状态

[root@node3 ~]# etcdctl cluster-health

cluster is healthy

集群成员查看

[root@node3 ~]# etcdctl member list

删除集群成员

[root@node2 ~]# etcdctl member remove b200a8bec19bd22e

Removed member 4d11141f72b2744c from cluster

[root@node2 ~]# etcdctl member list

添加集群成员

注意:步骤很重要，不然会报集群ID不匹配

[root@node2 ~]# etcdctl member add --help

NAME:

etcdctl member add - add a new member to the etcd cluster

USAGE:

etcdctl member add

1.将目标节点添加到集群

Added member named etcd3 with ID 28e0d98e7ec15cd4 to cluster

ETCD_NAME="etcd3"

ETCD_INITIAL_CLUSTER_STATE="existing"

[root@node2 ~]# etcdctl member list

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

3.在目标节点上启动etcd

etcd --name etcd3 --data-dir /opt/etcd \

--initial-cluster-token etcd-cluster-1 \

--initial-cluster-state existing

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

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

[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}}

四.systemd管控

1.建用户etcd

useradd -r -s /sbin/nologin etcd

chown -R etcd: /opt/etcd

2.创建systemd服务脚本etcd.service

cat >/lib/systemd/system/etcd.service <

[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 <

name: etcd2

data-dir: "/opt/etcd"

HERE

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

Loaded: loaded (/usr/lib/systemd/system/etcd.service; enabled; vendor preset: disabled)

Active: active (running) since 五 2016-08-12 03:06:30 CST; 8min ago

Main PID: 12099 (etcd)

CGroup: /system.slice/etcd.service

└─12099 /usr/local/bin/etcd --config-file /etc/etcd.conf

Hint: Some lines were ellipsized, use -l to show in full.