Etcd是coreos开发的一个kv的软件，我使用他做存储数据，比如持久化固定ip，就是把固定的docker容器ip信息存放到etcd里，智能配置docker防火墙的信息也是存放到etcd里，这个软件很小型，并且支持集群，很是方便，现在给大家介绍一下如何在centos6系统里安装此软件。
先简单介绍一下etcd，从网上复制的
etcd是一个高可用的键值存储系统，主要用于共享配置和服务发现。 etcd的特性如下： 简单: curl可访问的用户的API（HTTP+JSON） 安全: 可选的SSL客户端证书认证 快速: 单实例每秒 1000 次写操作 可靠: 使用Raft保证一致性
安装环境
系统：centos6.6
etcd版本0.4.6
虽然有最新的版本，但我一直使用这个版本，比较稳定
下面是安装过程
1、下载
curl -L https://github.com/coreos/etcd/releases/download/v0.4.6/etcd-v0.4.6-linux-amd64.tar.gz -o etcd-v0.4.6-linux-amd64.tar.gz
2、解压
tar xzvf etcd-v0.4.6-linux-amd64.tar.gz cd etcd-v0.4.6-linux-amd64
3、复制程序到系统环境
cp etcd /usr/local/bin cp etcdctl /usr/local/bin
4、设置运行脚本，绝对路径是/etc/init.d/etcd
#!/bin/bash
# Copyright 2013, Nathan Milford
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# /etc/init.d/etcd
#
# Startup script for etcd
#
# chkconfig: 2345 20 80
# description: Starts and stops etcd
. /etc/init.d/functions
prog="etcd"
prog_bin="/usr/local/bin/$prog"
desc="etcd shared configuration and service discovery daemon"
if ! [ -f $prog_bin ]; then
echo "$prog binary not found."
exit 5
fi
if [ -f /etc/sysconfig/$prog ]; then
. /etc/sysconfig/$prog
else
echo "No sysconfig file found in /etc/sysconfig/$prog... exiting."
exit 5
fi
start() {
echo "Starting $desc ($prog): "
su $ETCD_USER -c "nohup $prog_bin $ETCD_OPTS >>$ETCD_OUT_FILE 2>&1 &"
RETVAL=$?
return $RETVAL
}
stop() {
echo "Shutting down $desc ($prog): "
pkill -f $prog_bin
}
restart() {
stop
start
}
status() {
if [ -z $pid ]; then
pid=$(pgrep -f $prog_bin)
fi
if [ -z $pid ]; then
echo "$prog is NOT running."
return 1
else
echo "$prog is running (pid is $pid)."
fi
}
case "$1" in
start) start;;
stop) stop;;
restart) restart;;
status) status;;
*) echo "Usage: $0 {start|stop|restart|status}"
RETVAL=2;;
esac
exit $RETVAL
5、设置etcd软件环境配置，根据自己的实际环境修改
09:21:19 # cat /etc/sysconfig/etcd
#!/bin/bash
# Copyright 2014, Nathan Milford
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
lib_dir='/var/lib/etcd/'
# Will be used to populate IP address values below. Setting some items to
# '0.0.0.0' is not compatable with the discovery API.
#_MY_IPADDR=$(/sbin/ifconfig | grep 'inet'| grep -Ev '(127|117|172|::1|fe)' |awk '{print $2}'|head -n 1)
_MY_IPADDR=10.10.29.236
# Daemon User
#ETCD_USER="etcd"
# Cluster Seeds
# You can specify a list here sepearated by commas, or leave it blank if
# you're playing with a single node.
ETCD_SEEDS=""
# Discovery Endpoint
# Leave it as the public URL unless you are running your own.
ETCD_DISCOVER_ENDPOINT="https://discovery.etcd.io/"
# Discovery Token
# If you are using the discovery protocol you can grab your cluster token
# from https://discovery.etcd.io/new if you are not hosting it yourself.
ETCD_DISCOVERY_TOKEN="cb5940a807d44287e05f29f3170883e3"
# This node's name as it represents itself on the cluster.
ETCD_NODE_NAME=$(hostname -s)
# Hostname and port for the etcd server to work on.
ETCD_LISTEN="$_MY_IPADDR:4001"
# Directory to store log and snapshot.
ETCD_DATA_DIR="/var/lib/etcd/"
# File to log stdout/stderr to.
ETCD_OUT_FILE="/var/log/etcd/etcd.log"
# Set logging vebosity for the file above.
# Valid options are "", "v" or "vv"
ETCD_LOGGING=""
# Max size of the cluster.
ETCD_MAXSIZE=9
# Max size of result buffer.
ETCD_MAXRESULT=1024
# Number of retries to attempt while joining a cluster
ETCD_RETRIES=3
# Set security settings for the etcd server.
# Leave blank if you do not plan to use this feature, otherwise add appropriate
# paths.
ETCD_CAFILE=""
ETCD_CERT=""
ETCD_KEY=""
# Toggles snapshotting.
# Keep blank or set to true.
ETCD_SNAPSHOT=""
# Hostname and port for the RAFT server to work on.
RAFT_LISTEN="$_MY_IPADDR:7001"
# Set security settings for the RAFT server.
# Leave blank if you do not plan to use this feature, otherwise add appropriate
# paths.
RAFT_CAFILE=""
RAFT_CERT=""
RAFT_KEY=""
# Below we build the opts to pass to the init script.
ETCD_OPTS="-name=${ETCD_NODE_NAME} \
-addr=${ETCD_LISTEN} \
-peer-addr=${RAFT_LISTEN} \
-data-dir=${ETCD_DATA_DIR} \
-max-result-buffer=${ETCD_MAXRESULT} \
-max-cluster-size=${ETCD_MAXSIZE} \
-max-retry-attempts=${ETCD_RETRIES}"
if [ x$ETCD_SEEDS != "x" ]; then
ETCD_OPTS="$ETCD_OPTS -peers=${ETCD_SEEDS}"
fi
if [ x$ETCD_DISCOVERY_TOKEN != "x" ]; then
ETCD_OPTS="$ETCD_OPTS -discovery=${ETCD_DISCOVER_ENDPOINT}${ETCD_DISCOVERY_TOKEN}"
fi
if [ "$ETCD_LOGGING" == "v" ]; then
ETCD_OPTS="$ETCD_OPTS -v"
elif [ "$ETCD_LOGGING" == "vv" ]; then
ETCD_OPTS="$ETCD_OPTS -vv"
fi
if [ x$ETCD_SNAPSHOT != "x" ]; then
ETCD_OPTS="$ETCD_OPTS -snapshot"
fi
if [ ! -d $lib_dir ];then
mkdir -p $lib_dir
fi
#if [ x$ETCD_CAFILE != "x" ] && [ x$ETCD_CERT != "x" ] && [ x$ETCD_KEY != "x" ]; then
# ETCD_OPTS="$ETCD_OPTS -ca-file=${ETCD_CAFILE} -cert-file=${ETCD_CERT} -key-file=${ETCD_KEY}"
#fi
#if [ x$RAFT_CAFILE != "x" ] && [ x$RAFT_CERT != "x" ] && [ x$RAFT_KEY != "x" ]; then
# ETCD_OPTS="$ETCD_OPTS -peer-ca-file=${RAFT_CAFILE} -peer-cert-file=${RAFT_CERT} -peer-key-file=${RAFT_KEY}"
#fi
#echo $ETCD_OPTS
# TODO
# Add support for:
# -peers-file
# -config
# -cors
# -cpuprofile
如果不想加入集群，就把ETCD_DISCOVER_ENDPOINT与ETCD_DISCOVERY_TOKEN给注释了，另外_MY_IPADDR是本机的ip
6、创建用户
useradd etcd -M -s /sbin/nologin
7、创建日志与数据存放目录
mkdir /var/log/etcd mkdir /var/lib/etcd
8、授予权限
chown -R etcd:etcd /var/log/etcd chown -R etcd:etcd /var/lib/etcd
9、启动
/etcd/init.d/etcd start
10、设置开机启动
chkconfig --level 345 etcd on
11、查看运行情况
查看集群主机ip
12:22:48 # curl -L http://127.0.0.1:4001/v2/machines http://10.10.21.199:4001, http://10.10.27.221:4001, http://10.10.17.3:4001, http://10.10.17.4:4001, http://10.10.29.236:4001
查看集群主机列表（详细）
12:23:07 # curl -L http://127.0.0.1:4001/v2/keys/_etcd/machines
{"action":"get","node":{"key":"/_etcd/machines","dir":true,"nodes":[{"key":"/_etcd/machines/docker-test1","value":"etcd=http%3A%2F%2F10.10.21.199%3A4001\u0026raft=http%3A%2F%2F10.10.21.199%3A7001","modifiedIndex":1,"createdIndex":1},{"key":"/_etcd/machines/docker-test2","value":"etcd=http%3A%2F%2F10.10.27.221%3A4001\u0026raft=http%3A%2F%2F10.10.27.221%3A7001","modifiedIndex":9,"createdIndex":9},{"key":"/_etcd/machines/docker-test3","value":"etcd=http%3A%2F%2F10.10.17.3%3A4001\u0026raft=http%3A%2F%2F10.10.17.3%3A7001","modifiedIndex":16,"createdIndex":16},{"key":"/_etcd/machines/ip-10-10-17-4","value":"etcd=http%3A%2F%2F10.10.17.4%3A4001\u0026raft=http%3A%2F%2F10.10.17.4%3A7001","modifiedIndex":177304,"createdIndex":177304},{"key":"/_etcd/machines/ip-10-10-29-236","value":"etcd=http%3A%2F%2F10.10.29.236%3A4001\u0026raft=http%3A%2F%2F10.10.29.236%3A7001","modifiedIndex":2101510,"createdIndex":2101510}],"modifiedIndex":1,"createdIndex":1}}
查看集群header
12:23:15 # curl -L http://127.0.0.1:4001/v2/leader http://10.10.17.4:7001
详细请参考https://github.com/coreos/etcd