The so-called reverse proxy is to replace the server to accept the user's request , obtain the user's required resources from the target server, and then send it to the user

1.2 What is load balancing

The data traffic is distributed to multiple servers for execution, reducing the pressure on each server, and multiple servers work together to complete the task, thus improving the data throughput.

1.3 What is dynamic and static separation

Dynamic and static separation: put static resources on the reverse proxy server to save users' access time

Nginx classifies and forwards client requests, and requests for static resources are processed by the static resource server (web server).

Dynamic resource requests are processed by tomcat (web application server), which can improve the performance of the entire service

web application server, such as:
- tomcat
- resin
- jetty
web server, such as:
- Apache server
- Nginx
- IIS

Distinction: The web server cannot parse pages such as jsp, but can only process static resources such as js, css, and html.

Concurrency: The concurrency capability of web servers is much higher than that of web application servers.

1.4 Install Nginx

Download the nginx installation package

Install nginx dependencies

yum -y install gcc pcre pcre-devel zlib zlib-devel openssl openssl-devel

Unzip the installation package

tar -zxvf nginx-1.10.0.tar.gz

Configure nginx installation package

cd nginx-1.10.0

//Install nginx to the /usr/java/nginx directory

./configure --prefix=/usr/local/nginx

compile and install

make && make install

1.5 Startup and shutdown of Nginx

start up

#There is a sbin directory under the nginx directory, and there is an nginx executable program under the sbin
directory./nginx

closure

./nginx -s stop

Load configuration files dynamically (restart)

#You can update the configuration file without closing nginx./nginx
-s reload

1.6 Configuration file introduction (nginx.conf)

#user  nobody;
#工作进程
worker_processes  1;

events {
    #连接池连接数
    worker_connections  1024;
}
#请求方式
http {
    #媒体类型
    include       mime.types;
    #默认媒体类型 二进制
    default_type  application/octet-stream;
    #上传文件
    sendfile        on;
    #超时时间
    keepalive_timeout  65;

    #gzip  on;
    #服务器配置
	server {
        #监听端口
        listen       80;
        #监听域名
        server_name  localhost;
        #请求头信息
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        #请求映射规则，/代表所有请求路径
        location / {
             #请求转发地址
             #root html;
			 proxy_pass http://manage.powershop.com:8080;
             #欢迎页
             #index  index.html index.htm;
             #转发连接超时时间
			proxy_connect_timeout 600;
             #转发读取超时时间
			proxy_read_timeout 600;
        }
    }
}

1.7 Nginx proxy tomcat

Install two tomcats in linux and modify the port number

Proxy a tomcat (reverse proxy)

Modify the nginx/conf/nginx.conf file:

location / { #Request forwarding address root html; proxy_pass http://127.0.0.1:8080; #Welcome page index index.html index.htm; }

Proxy multiple tomcats (load balancing)

1. Add an upstream to the http node

2. Modify the reverse proxy under location /

1.8 Six load balancing strategies of Nginx

load balancing strategy	illustrate
polling	default
weight	weight method
ip_hash	According to the ip allocation method
least_conn	By number of connections
fair	by response time
url_hash	Assign by URL

Weights

upstream server_list{

server localhost:8080 weight=5;

server localhost:8090 weight=1;

}

ipash

upstream server_list{

ip_hash

server localhost:8080;

server localhost:8090;

}

1.9 Session sharing of Tomcat cluster

1. Add ip_hash to the upstream of nginx (this is not session sharing. Personal understanding is a tricky way, and after one side of the server goes down, the login status will be lost.) 2. The session sharing method that comes with the tomcat
cluster (When I tried it personally, I confirmed that the tomcat cluster in this way needs to be deployed on the same server, so that high availability cannot be achieved after the server is down, but it is indeed very convenient. The scalability is not high, and it can be used as a small cluster 3.
Tomcat cluster and redis realize session sharing (highly recommended)

The first type (ip_hash above)

the second

Enter the installation path of tomcat, find the conf file and modify conf/server.xml.

Add the following code to <Engine name="Catalina" defaultHost="localhost"> in the configuration file

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"

channelSendOptions="8">

<Manager className="org.apache.catalina.ha.session.DeltaManager"

expireSessionsOnShutdown="false"

notifyListenersOnReplication="true"/>

<Channel className="org.apache.catalina.tribes.group.GroupChannel">

<Membership className="org.apache.catalina.tribes.membership.McastService"

address="228.0.0.4"

port="45564"

frequency="500"

dropTime="3000"/>

<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"

address="auto"

port="4000"

autoBind="100"

selectorTimeout="5000"

maxThreads="6"/>

<Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">

<Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>

</Sender>

<Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>

<Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>

</Channel>

<Valve className="org.apache.catalina.ha.tcp.ReplicationValve"

filter=""/>

<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>

<Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer"

tempDir="/opt/tomcat/tmp/war-temp/"

deployDir="/opt/tomcat/tmp/war-deploy/"

watchDir="/opt/tomcat/tmp/war-listen/"

watchEnabled="false"/>

<ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener"/>

<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>

</Cluster>

After saving, modify the deployed project and add tags in web.xml

<distributable/>

Restart the tomcat cluster to realize session sharing, please pay attention! ! The tomcat cluster needs to be on the same server , otherwise session sharing cannot be achieved.

third

1.redis配置（192.168.159.131:16300）（v2.8.3）

2.tomcat配置

tomcat1（192.168.159.130:8081）

tomcat2（192.168.159.130:8082）

3.nginx安装在192.168.159.131。

       首先，是配置tomcat，使其将session保存到redis上。有两种方法，也是在server.xml或context.xml中配置，不同的是memcached只需要添加一个manager标签，而redis需要增加的内容如下：（注意：valve标签一定要在manager前面。）

<Valve className="com.radiadesign.catalina.session.RedisSessionHandlerValve" />
<Manager className="com.radiadesign.catalina.session.RedisSessionManager"
         host="192.168.159.131"
         port="16300" 
         database="0" 
         maxInactiveInterval="60"/>
其次，配置nginx，用于测试session保持共享。

upstream  redis.xxy.com  {
      server   192.168.159.130:8081;
      server   192.168.159.130:8082;
}

log_format  www_xy_com  '$remote_addr - $remote_user [$time_local] $request '
               '"$status" $body_bytes_sent "$http_referer"' 
               '"$http_user_agent" "$http_x_forwarded_for"';

server
{
      listen  80;
      server_name redis.xxy.com; 

      location / {
               proxy_pass        http://redis.xxy.com;
               proxy_set_header   Host             $host;
               proxy_set_header   X-Real-IP        $remote_addr;
               proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
      }

      access_log  /data/base_files/logs/redis.xxy.log  www_xy_com;
}
最后，将你的应用放到两个tomcat中，并依次启动redis、tomcat、nginx。访问你的nginx，可以发现两个tomcat中的session可以保持共享了。
如果tomcat配置中，将manager放在server.xml中，那么使用maven做热部署时，会发生失败。所以，推荐放在context.xml中。

2.0 static and dynamic separation

Create static resources

Create a new images folder in the virtual machine and upload pictures

Configure the nginx.conf of nginx

location ~* \.(gif|jpg|png|jpeg)$ {
root /usr/upload/images;
}

test

http://192.168.202.129/atm.jpg

2.1 nginx solves the port problem

example:

For example, the address accessed by one of our local projects is: 127.0.0.1:8080

We can use the following settings to access www.powershop.com

1. Modify local files

C:/Windows/System32/drivers/etc/hosts

2. Set the proxy ip and port number in the nginx.conf file in nginx

server {
listen 80;
server_name localhost;

       location / {

#If you are using nginx on linux, here the ip is set to the local ip
           proxy_pass http://127.0.0.1:8080;
           proxy_connect_timeout 600;
           proxy_read_timeout 600;
       }
}

3. Process flow

1. The browser is ready to initiate a request to visit http://powershop.com , but domain name resolution is required

2. Because we have set it in the hosts file, the local domain name resolution will be prioritized, and the obtained ip address is:

127.0.0.1

3. The request is sent to the parsed ip, and port 80 is used by default: http://127.0.0.1:80

The local nginx has been listening to port 80, so capture this request

4. Reverse proxy rules are configured in nginx to proxy powershop.com to 127.0.0.1:8080, so the request is forwarded

5. The background management system gets the 127.0.0.1:8080 request and processes it, and returns the response to nginx after completion

6. nginx returns the result to the browser

Nginx (reverse proxy, load balancing, dynamic and static separation, tomcat cluster session sharing)

1. What is Nginx?

1.1 What is a reverse proxy