etcd3学习笔记
etcd 是什么？
中文：etcd是一个分布式一致性键值存储，其主要用于分布式系统的共享配置和服务发现
英文：A distributed, reliable key-value store for the most critical data of a distributed system
1、学习文档
英文：https://coreos.com/etcd/docs/latest/learning/data_model.html
辅助文档：https://legacy.gitbook.com/book/skyao/learning-etcd3/details
2、简单搭建单例测试
主要参考：https://coreos.com/etcd/docs/latest/dl_build.html
简单测试：https://github.com/coreos/etcd/releases
下载最新的版本
./etcd
ETCDCTL_API=3 etcdctl put michael 111
ETCDCTL_API=3 etcdctl get michael
为了简单起见：配置环境变量 /etc/profile
指定客户端工具etcdctl使用api v3和服务器程序etcd进行通信
```
export PATH=$PATH:/home/etcd/etcd335
export ETCDCTL_API=3
```
source /etc/profile
3、本地快速搭建集群测试
主要参考：https://coreos.com/etcd/docs/latest/demo.html
首先安装goreman go get -v github.com/mattn/goreman
然后下载 https://github.com/coreos/etcd/blob/master/Procfile
goreman -f Procfile start 即可快速开启一个本地集群
# Use goreman to run `go get github.com/mattn/goreman`
etcd1: etcd --name infra1 --listen-client-urls http://127.0.0.1:2379 --advertise-client-urls http://127.0.0.1:2379 --listen-peer-urls http://127.0.0.1:12380 --initial-advertise-peer-urls http://127.0.0.1:12380 --initial-cluster-token etcd-cluster-1 --initial-cluster 'infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380' --initial-cluster-state new --enable-pprof
etcd2: etcd --name infra2 --listen-client-urls http://127.0.0.1:22379 --advertise-client-urls http://127.0.0.1:22379 --listen-peer-urls http://127.0.0.1:22380 --initial-advertise-peer-urls http://127.0.0.1:22380 --initial-cluster-token etcd-cluster-1 --initial-cluster 'infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380' --initial-cluster-state new --enable-pprof
etcd3: etcd --name infra3 --listen-client-urls http://127.0.0.1:32379 --advertise-client-urls http://127.0.0.1:32379 --listen-peer-urls http://127.0.0.1:32380 --initial-advertise-peer-urls http://127.0.0.1:32380 --initial-cluster-token etcd-cluster-1 --initial-cluster 'infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380' --initial-cluster-state new --enable-pprof
# in future, use proxy to listen on 2379
#proxy: bin/etcd --name infra-proxy1 --proxy=on --listen-client-urls http://127.0.0.1:2378 --initial-cluster 'infra1=http://127.0.0.1:12380,infra2=http://127.0.0.1:22380,infra3=http://127.0.0.1:32380' --enable-pprof
etcdctl --endpoints=localhost:22379 put michael 222
etcdctl --endpoints=localhost:22379 get michael
测试其他操作：1、Set up a cluster 2、Transactional write 3、Watch 4、Lease 5、Distributed locks 6、Elections 7、Auth
其他参数解释：
https://github.com/coreos/etcd/blob/master/Documentation/op-guide/configuration.md
or
https://blog.csdn.net/varyall/article/details/79128181
or
https://legacy.gitbook.com/book/skyao/learning-etcd3/details
or
https://alexstocks.github.io/html/etcd.html
4、3台机器搭建的最小集群
name | 内网ip | 外网ip
---------- | ---------------- | --------
mt1 | 10.105.79.74 | ***
mt2 | 10.105.90.27 | ***
mt2 | 10.154.6.123 | ***
```
#### mt1 上执行
nohup etcd –name infra0 –initial-advertise-peer-urls http://10.105.79.74:2380
–listen-peer-urls http://10.105.79.74:2380
–listen-client-urls http://10.105.79.74:2379,http://127.0.0.1:2379
–advertise-client-urls http://10.105.79.74:2379
–initial-cluster-token etcd-cluster-1
–initial-cluster infra0=http://10.105.79.74:2380,infra1=http://10.105.90.27:2380,infra2=http://10.154.6.123:2380
–initial-cluster-state new
–data-dir=/data/etcdir/ > /var/log/etcd.log 2>&1 &
#### mt2 上执行
nohup etcd –name infra1 –initial-advertise-peer-urls http://10.105.90.27:2380
–listen-peer-urls http://10.105.90.27:2380
–listen-client-urls http://10.105.90.27:2379,http://127.0.0.1:2379
–advertise-client-urls http://10.105.90.27:2379
–initial-cluster-token etcd-cluster-1
–initial-cluster infra0=http://10.105.79.74:2380,infra1=http://10.105.90.27:2380,infra2=http://10.154.6.123:2380
–initial-cluster-state new
–data-dir=/data/etcdir/ > /var/log/etcd.log 2>&1 &
#### mt3 上执行
nohup etcd –name infra2 –initial-advertise-peer-urls http://10.154.6.123:2380
–listen-peer-urls http://10.154.6.123:2380
–listen-client-urls http://10.154.6.123:2379,http://127.0.0.1:2379
–advertise-client-urls http://10.154.6.123:2379
–initial-cluster-token etcd-cluster-1
–initial-cluster infra0=http://10.105.79.74:2380,infra1=http://10.105.90.27:2380,infra2=http://10.154.6.123:2380
–initial-cluster-state new
–data-dir=/data/etcdir/ > /var/log/etcd.log 2>&1 &
```
MarkDown表格表示
http://xianbai.me/learn-md/article/extension/table.html
5、etcd 角色控制
http://www.huweihuang.com/article/etcd/etcd-auth&security/
6、etcd 客户端介绍
参考：https://yuerblog.cc/2017/12/12/etcd-v3-sdk-usage/
7、使用etcd作为服务注册的例子
参考：
https://ralphbupt.github.io/2017/05/04/etcd-%E6%9C%8D%E5%8A%A1%E6%B3%A8%E5%86%8C%E4%B8%8E%E5%8F%91%E7%8E%B0/
https://daizuozhuo.github.io/etcd-service-discovery/
8、使用etcd作为gRPC服务发现&负载均衡的例子
https://segmentfault.com/a/1190000008672912#articleHeader3
9、etcd：从应用场景到实现原理的全方位解读
http://www.infoq.com/cn/articles/etcd-interpretation-application-scenario-implement-principle