摘要：實現無需動態負載均衡實現無需動態負載均衡環境搭建出現下面提示說明成功啟動是新浪微博開源的基于實現動態配置的三方模塊。配置動態負載均衡創建指定從拉取的上游服務器后持久化到的位置，這樣即使服務器出問題了，本地還有一個備份。

傳統的負載均衡，如果Upstream參數發生變化，每次都需要重新加載nginx.conf文件,因此擴展性不是很高，所以我們可以采用動態負載均衡，實現Upstream可配置化、動態化，無需人工重新加載nginx.conf，類似分布式的配置中心

Consul+Consul-template 每次發現配置更改需要raload nginx，重啟Nginx。

Consul+OpenResty 實現無需raload動態負載均衡

Consul+upsync+Nginx 實現無需raload動態負載均衡

https://releases.hashicorp.com/consul/0.7.5/consul_0.7.5_linux_amd64.zip

yum -y install unzip

unzip consul_0.7.5_linux_amd64.zip

./consul 出現下面提示說明成功

[root@localhost local]# ./consul
usage: consul [--version] [--help]  []

Available commands are:
    agent          Runs a Consul agent
    configtest     Validate config file
    event          Fire a new event
    exec           Executes a command on Consul nodes
    force-leave    Forces a member of the cluster to enter the "left" state
    info           Provides debugging information for operators
    join           Tell Consul agent to join cluster
    keygen         Generates a new encryption key
    keyring        Manages gossip layer encryption keys
    kv             Interact with the key-value store
    leave          Gracefully leaves the Consul cluster and shuts down
    lock           Execute a command holding a lock
    maint          Controls node or service maintenance mode
    members        Lists the members of a Consul cluster
    monitor        Stream logs from a Consul agent
    operator       Provides cluster-level tools for Consul operators
    reload         Triggers the agent to reload configuration files
    rtt            Estimates network round trip time between nodes
    snapshot       Saves, restores and inspects snapshots of Consul server state
    version        Prints the Consul version
    watch          Watch for changes in Consul

5.啟動consul
./consul agent -dev -ui -node=consul-dev -client=192.168.102.129

Upsync是新浪微博開源的基于Nginx實現動態配置的三方模塊。Nginx-Upsync-Module的功能是拉取Consul的后端server的列表，并動態更新Nginx的路由信息。此模塊不依賴于任何第三方模塊。Consul作為Nginx的DB，利用Consul的KV服務，每個Nginx Work進程獨立的去拉取各個upstream的配置，并更新各自的路由。
nginx-upsync-module:

cd /usr/local

wget https://github.com/weibocom/nginx-upsync-module/archive/master.zip

unzip master.zip

unzip consul_0.7.1_linux_amd64.zip

tar -zxvf nginx-1.9.9.tar.gz

groupadd nginx

useradd -g nginx -s /sbin/nologin nginx

mkdir -p /var/tmp/nginx/client/

mkdir -p /usr/local/nginx

cd nginx-1.9.9/

./configure --prefix=/usr/local/nginx --user=nginx --group=root --with-http_ssl_module --with-http_flv_module --with-http_stub_status_module --with-http_gzip_static_module --with-http_realip_module --http-client-body-temp-path=/var/tmp/nginx/client/ --http-proxy-temp-path=/var/tmp/nginx/proxy/ --http-fastcgi-temp-path=/var/tmp/nginx/fcgi/ --http-uwsgi-temp-path=/var/tmp/nginx/uwsgi --http-scgi-temp-path=/var/tmp/nginx/scgi --with-pcre --add-module=../nginx-upsync-module-master

make && make install

創建upsync_dump_pathmkdir /usr/local/nginx/conf/servers/

upsync_dump_path指定從consul拉取的上游服務器后持久化到的位置，這樣即使consul服務器出問題了，本地還有一個備份。

添加nginx Upstream服務

使用linux命令方式發送put請求
curl -X PUT http://192.168.102.129:8500/v1/kv/upstreams/tmp/192.168.102.128:8081
curl -X PUT http://192.168.102.129:8500/v1/kv/upstreams/tmp/192.168.102.128:8081

使用postmen 發送put請求
http://192.168.102.129:8500/v1/kv/upstreams/tmp/192.168.102.128:8081
http://192.168.102.129:8500/v1/kv/upstreams/tmp/192.168.102.128:8081

負載均衡信息參數
{"weight":1, "max_fails":2, "fail_timeout":10, "down":0}

Upstream 動態配置
##動態去consul 獲取注冊的真實反向代理地址
upstream tmpup{

    server 127.0.0.1:11111;
    upsync 192.168.212.134:8500/v1/kv/upstreams/tmp upsync_timeout=6m upsync_interval=500ms upsync_type=consul strong_dependency=off;
    upsync_dump_path /usr/local/nginx/conf/servers/servers_test.conf;
}

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_pass http://tmpup;
        index  index.html index.htm;
    }
}

upsync指令指定從consul哪個路徑拉取上游服務器配置；upsync_timeout配置從consul拉取上游服務器配置的超時時間；upsync_interval配置從consul拉取上游服務器配置的間隔時間；upsync_type指定使用consul配置服務器；strong_dependency配置nginx在啟動時是否強制依賴配置服務器，如果配置為on，則拉取配置失敗時nginx啟動同樣失敗。upsync_dump_path指定從consul拉取的上游服務器后持久化到的位置，這樣即使consul服務器出問題了，本地還有一個備份。