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Haproxy+etcd+confd+Docker搭建节点自动发现的高可用负载均衡框架

2019-05-08 09:26 441 查看

操作系统：Centos 7.0

先扔出一张图来解释这四个组件之间的关系

下面细说

1.Haproxy

Haproxy不用多说，负载均衡软件，安装Haproxy

[code]yum -y install haproxy

版本是haproxy-1.5.4-3.el6.x86_64.rpm

2.etcd

etcd，是一个高可用的 Key/Value 的内存数据库，提供发布/订阅模式的操作，每当有新的后端节点加入的时候，我们都会用脚本操作到etcd上去发布新节点信息，而已经订阅该消息的confd客户端就会收到新节点的发布信息，它会修改配置文件且分发去覆盖本机的Haproxy的配置，并且重启Haproxy，以达到给Haproxy新增后端分发节点的目的，安装etcd

[code]

wget https://github.com/coreos/etcd/releases/download/v3.0.3/etcd-v3.0.3-linux-amd64.tar.gz

```
tar xvf etcd-v3.0.3-linux-amd64.tar.gz
```

[root@201 data]# cd etcd-v3.0.3-linux-amd64/

[root@201 etcd-v3.0.3-linux-amd64]# cp etcd* /bin/

[root@201 etcd-v3.0.3-linux-amd64]# etcd -version

```
etcd Version: 3.0.3
```
```
Git SHA: 24a90ba
```
```
Go Version: go1.6.2
```
```
Go OS/Arch: linux/amd64
```

启动etcd

[code]

[root@201 data]# etcd --listen-peer-urls 'http://192.168.1.204:2380' --advertise-client-urls 'http://192.168.1.204:2379' --listen-client-urls 'http://192.168.1.204:2379' -data-dir /data/default.etcd -name etcd1 &

```
查看其监听的端口
```
```
[root@201 data]# netstat -npl|grep etcd
```

tcp 0 0 127.0.0.1:2379 0.0.0.0:* LISTEN 4750/etcd

tcp 0 0 127.0.0.1:2380 0.0.0.0:* LISTEN 4750/etcd

```
设置测试key value
```

[root@201 data]# curl -L http://192.168.1.204:2379/v2/keys/key1 -XPUT -d value="Hello world"

{"action":"set","node":{"key":"/key1","value":"Hello world","modifiedIndex":5,"createdIndex":5}}

```
查询测试key
```

[root@201 data]# curl -L http://192.168.1.204:2379/v2/keys/key1

{"action":"get","node":{"key":"/key1","value":"Hello world","modifiedIndex":5,"createdIndex":5}}

```
删除key
```

curl -XDELETE http://192.168.1.204:2379/v2/keys/app/servers

另外还可以用etcdctl命令来操作，创建一个新的目录和键分别使用 etcdctl mkdir 和 etcdctl mk 命令。

```
[root@201 data]# etcdctl mkdir /demo
```
```
[root@201 data]# etcdctl get /demo
```
```
/demo: is a directory
```

[root@201 data]# etcdctl mk /demo/hello "Hello Etcd" # 实际情况中这里会回显输出“Hello Etcd”，省略

[root@201 data]# etcdctl get /demo/hello

```
Hello Etcd
```

3.confd

上面说过了，confd是分发新的配置到Haproxy中，安装confd

[code]

wget https://github.com/kelseyhightower/confd/releases/download/v0.11.0/confd-0.11.0-linux-amd64

[root@201 data]# mv confd-0.11.0-linux-amd64 /usr/local/bin/confd

[root@201 data]# chmod +x /usr/local/bin/confd

```
[root@201 data]# confd -version
```
```
confd 0.11.0
```

confd要与haproxy安装在同一台主机上，以便能生成给Haproxy用的配置。创建confd的默认配置存放路径，confd会根据该文件找到要修改的haproxy文件路径

[code]

[root@201 data]# mkdir -p /etc/confd/templates

```
vim /etc/confd/conf.d/haproxy.toml
```
```
[template]
```
```
#模板文件，基于它进行修改
```
```
src = "haproxy.cfg.tmpl"
```
```
#haproxy的默认配置路径
```
```
dest = "/etc/haproxy/haproxy.cfg"
```
```
#keys是在etcd上订阅消息的前缀
```
```
keys = [
```
```
"/app/servers",
```
```
]
```
```
#更新配置后重启haproxy
```

reload_cmd = "/etc/init.d/haproxy reload"

创建haproxy.cfg的模板文件，以便confd能根据模板生成配置，语法格式是基于Go语言的语法

vim /etc/confd/templates/haproxy.cfg.tmpl

[code]

```
global
```
```
log 127.0.0.1 local3
```
```
maxconn 5000
```
```
uid 99
```
```
gid 99
```
```
daemon
```
```
defaults
```
```
log 127.0.0.1 local3
```
```
mode http
```
```
option dontlognull
```
```
retries 3
```
```
option redispatch
```
```
maxconn 2000
```
```
timeout connect 5000
```
```
timeout client 50000
```
```
timeout server 50000
```
```
frontend myhttp
```
```
mode http
```
```
bind 192.168.1.204:80
```
```
use_backend myserver
```
```
backend myserver
```
```
mode http
```
```
balance roundrobin
```
```
#confd的语法会替换下面的变量
```
```
{{range gets "/app/servers/*"}}
```

server {{base .Key}} {{.Value}} weight 10

```
{{end}}
```

启动con 3ff7 fd

[code]confd -interval 10 -node '192.168.1.204:2379' -confdir /etc/confd > /var/log/confd.log &

这样当我们手动修改haproxy.cfg.tmpl文件以后，每隔不到10s左右的时间，confd都会发现模板文件已经更新，会重新生成配置发布，看到更新时候的日志如下

[code]

2016-07-23T21:45:39+08:00 204.localdomain confd[3317]: INFO /etc/haproxy/haproxy.cfg has md5sum 4b3b5d42ffd945117fe74d5d234ae49b should be e81aa47326241d0d1530c9d4b13e1e39

2016-07-23T21:45:39+08:00 204.localdomain confd[3317]: INFO Target config /etc/haproxy/haproxy.cfg out of sync

2016-07-23T21:45:39+08:00 204.localdomain confd[3317]: INFO Target config /etc/haproxy/haproxy.cfg has been updated

4.docker启动脚本

我们启动docker要写一个脚本，先启动docker，得到容器id。然后更新信息到etcd上，进而出发confd发布新的配置给Haproxy，这样在Haproxy配置文件中将我们新启动的容器ip地址添加到后端列表，以达到注册新节点的目的。记住启动和停止docker都要用这个脚本，不要直接使用docker命令，因为脚本还要处理etcd的信息。

docker.sh

[code]

```
--dns 172.17.42.1
```
```
#!/bin/bash
```
```
if [ -z $1 ]; then
```

echo "Usage: c start <image name>:<version>"

```
echo " c stop <container name>"
```
```
exit 1
```
```
fi
```

# etcd地址我先写死了，最好改成用脚本获取

```
if [ -z $ETCD_HOST ]; then
```
```
ETCD_HOST="192.168.1.204:2379"
```
```
fi
```
```
if [ -z $ETCD_PREFIX ]; then
```
```
ETCD_PREFIX="app/servers"
```
```
fi
```
```
if [ -z $CPORT ]; then
```
```
CPORT="80"
```
```
fi
```
```
# 网卡是eth?要写清楚
```
```
if [ -z $FORREST_IP ]; then
```

FORREST_IP=`ifconfig eth1| grep "inet addr" | head -1 | cut -d : -f2 | awk '{print $1}'`

```
fi
```
```
# 启动docker
```
```
function launch_container {
```

echo "Launching $1 on $FORREST_IP and mapped port $CPORT to ..."

CONTAINER_ID=`docker run -d -P $1 python app.py`

#CONTAINER_ID=`docker run -d -P -v /data:/data -v /etc/httpd/conf:/etc/httpd/conf -v /etc/httpd/conf.d:/etc/httpd/conf.d -v /etc/localtime:/etc/localtime:ro $1 /bin/sh -c "/usr/bin/supervisord -c /etc/supervisord.conf"`

PORT=`docker inspect $CONTAINER_ID|grep "\"Ports\"" -A 50|grep "\"$CPORT/tcp\"" -A 3| grep HostPort|cut -d '"' -f4|head -1`

NAME=`docker inspect $CONTAINER_ID | grep Name | cut -d '"' -f4 | sed "s/\///g"|sed -n 1p`

```
echo "Announcing to $ETCD_HOST..."
```

# 发布到etcd上去，触发confd刷新haproxy的配置，以注册新节点

args="http://$ETCD_HOST/v2/keys/$ETCD_PREFIX/$NAME -d value=$FORREST_IP:$PORT"

```
#echo "curl -XPUT "$args
```
```
curl -XPUT $args
```

echo "$1 running on Port $PORT with name $NAME"

```
}
```
```
# 停止docker
```
```
function stop_container {
```
```
echo "Stopping $1..."
```

CONTAINER_ID=`docker ps -a| grep $1 | awk '{print $1}'`

```
echo "Found container $CONTAINER_ID"
```
```
docker stop $CONTAINER_ID
```

echo http://$ETCD_HOST/v2/keys/$ETCD_PREFIX/$1

curl -XDELETE http://$ETCD_HOST/v2/keys/$ETCD_PREFIX/$1 &> /dev/null

```
echo "Stopped."
```
```
}
```
```
if [ $1 = "start" ]; then
```
```
launch_container $2
```
```
else
```
```
stop_container $2
```
```
fi
```

一开始绑定eth0，发现一直失败，原来网卡绑定错了，后来改成eth1了。

5.测试

启动两个后端镜像试试

[code]

```
启动第一个服务
```

[root@204 data]# ./docker.sh run tutum/lamp

Launching tutum/lamp on 192.168.1.204 and mapped port 80 to ...

```
Announcing to 192.168.1.204:2379...
```

{"action":"set","node":{"key":"/app/servers/boring_goldstine","value":"192.168.1.204:32769","modifiedIndex":4,"createdIndex":4}}

tutum/lamp running on Port 32769 with name boring_goldstine

```
启动第二个服务
```

[root@204 data]# ./docker.sh run tutum/lamp

Launching tutum/lamp on 192.168.1.204 and mapped port 80 to ...

```
Announcing to 192.168.1.204:2379...
```

{"action":"set","node":{"key":"/app/servers/fervent_curie","value":"192.168.1.204:32771","modifiedIndex":5,"createdIndex":5}}

tutum/lamp running on Port 32771 with name fervent_curie

执行上述命令的同时，由于etcd发生了变化，confd订阅的消息会被触发更新Haproxy的配置，以下日志表示更新配置

[code]

2016-07-25T16:37:59+08:00 204.localdomain confd[1300]: INFO /etc/haproxy/haproxy.cfg has md5sum b363dce20b5df8e4f82a327532623cd8 should be 2ca9875a74f76e9aa3701c3675d768ed

2016-07-25T16:37:59+08:00 204.localdomain confd[1300]: INFO Target config /etc/haproxy/haproxy.cfg out of sync

2016-07-25T16:37:59+08:00 204.localdomain confd[1300]: INFO Target config /etc/haproxy/haproxy.cfg has been updated

查询下etcd中的配置

[code]

[root@204 data]# etcdctl --endpoints "http://192.168.1.204:2379,http://192.168.1.204:2380" ls /app/servers

```
/app/servers/boring_goldstine
```
```
/app/servers/fervent_curie
```

可见现在有boring_goldstine和fervent_curie两个服务，那么docker中应该也对应这两个NAMES

[code]

```
[root@204 data]# docker ps
```

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

965fceb923a0 tutum/lamp "/run.sh" 52 seconds ago Up 50 seconds 0.0.0.0:32771->80/tcp, 0.0.0.0:32770->3306/tcp fervent_curie

7bedfc46554b tutum/lamp "/run.sh" 54 seconds ago Up 53 seconds 0.0.0.0:32769->80/tcp, 0.0.0.0:32768->3306/tcp boring_goldstine

好，现在我们整套框架都搭建起来了，可以开始测试。

单独在浏览器去访问两个启动的server，都有响应（如果半天卡死先把防火墙关闭了，但是启动docker的时候则需要打开）http://192.168.1.204:32769/

同样另一台机器得到的结果也相同http://192.168.1.204:32771/

刚才是直接分别访问两个后端服务，那么我们从haproxy的入口处，80端口去访问下http://192.168.1.204

测试haproxy转发到后端机器成功了。为了更直观的看到haproxy到底转发到哪台后端服务器了，我们访问http://192.168.1.204/phpinfo.php，可以在输出的信息中看到机器名称 Linux 7bedfc46554b 2.6.32-431

或者Linux 965fceb923a0 2.6.32-431

，机器名称时不时的变化，说明后端访问分发到不同的服务器上去了。

6.遇到问题

etcd cluster is unavailable or misconfigured

操作如下命令的时候出错

[root@204 data]# etcdctl mkdir /app

Error: client: etcd cluster is unavailable or misconfigured

error #0: dial tcp 127.0.0.1:2379: getsockopt: connection refused

error #1: dial tcp 127.0.0.1:4001: getsockopt: connection refused

这是因为没有指定ip信息，加上ip就可以了，比如ls命令，这样写

etcdctl –endpoints “http://192.168.1.204:2379,http://192.168.1.204:2380” ls

停止一个容器，不要直接去操作docker，要用脚本，否则只停了容器而etcd中的配置信息不会删除掉，如下

[code]

[root@204 data]# ./docker.sh stop thirsty_lovelace

```
Stopping thirsty_lovelace...
```
```
Found container 08e68416006a
```
```
08e68416006a
```

http://192.168.1.204:2379/v2/keys/app/servers/thirsty_lovelace

```
Stopped.
```

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