tomcat
實驗1：Tomcat安裝css
[root@localhost ~]#cat /etc/centos-release
CentOS Linux release 7.5.1804 (Core)html
[root@localhost ~]#uname -r
3.10.0-862.el7.x86_64前端
使用系統自帶的jdk
yum install -y java-1.8.0-openjdk-devel
vim /etc/profile.d/java.sh
export JAVA_HOME=/usrjava
安裝Tomcat
yum install tomcat-webapps tomcat-admin-webapps tomcat-docs-webapp tomcat -y
systemctl start tomcat
tcp/8005,8009,8080都已打開，tomcat已啓動nginx
提供一測試類應用
cd /var/lib/tomcat/webapps/
mkdir ./test/{classes,lib,META-INF,WEB-INF} -pv
cd test/
vim index.jspgit
<%@ page language="java" %>
<%@ page language="java" %>
<html>
<head><title>TomcatB</title></head>
<body>
<h1><font color="green">TomcatB.magedu.com</font></h1>
<table align="centre" border="1">
<tr>
<td>Session ID</td>
<% session.setAttribute("magedu.com","magedu.com"); %>
<td><%= session.getId() %></td>
</tr>
<tr>
<td>Created on</td>
<td><%= session.getCreationTime() %></td>
</tr>
</table>
</body>
</html>
經過瀏覽器訪問
實驗2：配置nginx反代負載均衡tomcatgithub
按照實驗1搭建好兩臺tomcat主機web
配置nginx
yum install nginx -y
vim /etc/nginx/nginx.conf算法
upstream tomcatsrvs{
server 192.168.91.139:8080;
server 192.168.91.137:8080;
}
server {
server_name www.magedu.com;
location / {
proxy_pass http://tomcatserver;
}
}
實驗3：配置httpd反代負載均衡tomcat
yum install -y httpd
vim /etc/httpd/conf.d/httpd_tomcat.confapache
<proxy balancer://tomcatserver> 定義後端服務器組，名爲tomcatserver
balancermember http://192.168.91.139:8080
balancermember http://192.168.91.137:8080 若是與後端服務器使用ajp協議鏈接，把http改成ajp
proxyset lbmethod=byrequests 至關於輪詢（rr）
</proxy>
<virtualhost *:80>
servername www.magedu.com
proxyrequests off
proxypreservehost on
proxyvia on
<proxy *>
require all granted
</proxy>
proxypass / balancer://tomcatserver/
proxypassreverse / balancer://tomcatserver/
<location />
require all granted
</location>
</virtualhost>
balancermember有後端檢查功能，也可定義權重調度算法等等；參考文檔：
https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#proxypass
httpd反代相關設置：
http集羣調度算法：
byrequests:輪詢(默認)
bybusyness:加權輪詢
bytraffic:基於流量調度
定義後端調度主機狀態status：
D：至關於down不接受請求
I：強行設置爲健康
H：熱備，至關於backup
E：錯誤
N：不接受新請求
實驗4：httpd實現session sticky
vim /etc/httpd/conf.d/httpd_tomcat.conf
Header add Set-Cookie "ROUTEID=.%{BALANCER_WORKER_ROUTE}e; path=/" env=BALANCER_ROUTE_CHANGED
<proxy balancer://tomcatserver>
balancermember http://192.168.91.139:8080 route=TomcatA
balancermember http://192.168.91.137:8080 route=TomcatB
proxyset lbmethod=byrequests
proxyset stickysession=ROUTEID
</proxy>
<virtualhost *:80>
servername www.magedu.com
proxyrequests off
proxypreservehost on
proxyvia on
<proxy *>
require all granted
</proxy>
proxypass / balancer://tomcatserver/
proxypassreverse / balancer://tomcatserver/
<location />
require all granted
</location>
</virtualhost>
發現不論怎麼刷新都只會調度都固定的一臺後端服務器，而且Session ID不會改變
實驗5：Nginx實現session sticky
vim /etc/nginx/nginx.conf
upstream tomcatserver {
server 192.168.91.139:8080;
server 192.168.91.137:8080;
hash $request_uri consistent;
}
實驗6：httpd, tomcat cluster實現session sticky
官方文檔：http://tomcat.apache.org/tomcat-7.0-doc/cluster-howto.html
vim /etc/tomcat/server.xml
在server.xml中的Engine或Host下插入下面的代碼
<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" ##多播地址
port="45564" ##多播地址監聽的端口，同一個集羣必須相同
frequency="500" ##每隔0.5s發送一次心跳檢測
dropTime="3000"/> ##3s沒收到心跳檢測代表對方down
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
address="auto" ##不建議用auto,更改成本機提供服務的IP
port="4000"
autoBind="100" ##自動綁定事件
selectorTimeout="5000"
maxThreads="6"/> ##集羣內部最大線程，代表集羣中最多有7臺主機
<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="/tmp/war-temp/"
deployDir="/tmp/war-deploy/"
watchDir="/tmp/war-listen/"
watchEnabled="false"/>
<ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener"/> ##官方文檔這裏有錯誤，少告終尾的/
<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/> ####官方文檔這裏有錯誤，少告終尾的/
</Cluster>
在對應的站點目錄下，建立WEB-INF/web.xml文件，由於是測試因此直接複製全局的web.xml
cp /etc/tomcat/web.xml /var/lib/tomcat/webapps/test/WEB-INF/
vim /var/lib/tomcat/webapps/test/WEB-INF/web.xml
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<distributable/> ##添加這一段代碼，注意，不要放到註釋內部，開頭和結尾
systemctl restart tomcat
在httpd主機上
vim /etc/httpd/conf.d/vhost.conf
<proxy balancer://tcsrvs>
BalancerMember http://192.168.91.139:8080
BalancerMember http://192.168.91.137:8080
</Proxy>
<VirtualHost *:80>
ServerName www.magedu.com
ProxyVia On
ProxyRequests Off
ProxyPreserveHost On
<proxy *>
require all granted
</proxy>
ProxyPass / balancer://tcsrvs/
ProxyPassReverse / balancer://tcsrvs/
<location />
require all granted
</location>
</VirtualHost>
測試
發現輪詢調度到兩臺服務器上，可是Session ID保持不變
實驗6：使用memcache做爲tomcat的session server
簡述
memcach是 高性能、分佈式的內存對象緩存系統，memcache緩存時鍵和值都在內存中存儲，因此訪問速度很快，memcache緩存時要依賴於客戶端的智能，緩存的過程是客戶端先去訪問後端的tomcat服務器，而後再請求memcache將訪問的數據緩存下來，下次再訪問時就直接會訪問memcache中的緩存，這一點與varnish不一樣，varnish是客戶端直接去訪問varnish緩存服務器，若是緩存上面沒有，varnish會替客戶端到後端服務器上去尋找，而後緩存下來，因此memcache就被稱爲旁掛式緩存，強依賴於客戶端的智能
特性
緩存：cache，無持久存儲功能，由於存儲於內存當中斷電就會丟失；
bypass緩存，依賴於客戶端的智能；
k/v cache，僅支持存儲可流式化數據，也就是發送數據以前打碎，而後到接收端再重組的過程稱爲可流式化。
安裝和配置
yum install memcached
監聽的端口：11211/tcp, 11211/udp
memcached -h —能夠查看程序命令經常使用選項
命令：
統計類：stats, stats items, stats slabs, stats sizes
存儲類：set, add, replace, append在後面插入值, prepend在前面插入值
命令格式:
<command name> <key> <flags標誌位> <exptime> <bytes> <cas unique>
檢索類：get, delete, incr/decr自增和減
清空：flush_all
要想將會話保存至後端memcache中，而且每一個memcache都保存相同的會話，須要一個管理項目memcached-session-manager
項目地址：https://github.com/magro/memcached-session-manager
下載以下jar文件至各tomcat的/usr/share/tomcat/lib/目錄中，其中的
{6,7,8}要換成與tomcat版本相同的版本號。
asm-6.0.jar
minlog-1.3.1.jar
kryo-4.0.1.jar
msm-kryo-serializer-2.1.1.jar
kryo-serializers-0.42.jar
objenesis-2.6.jar
memcached-session-manager-2.1.1.jar
reflectasm-1.11.3.jar
memcached-session-manager-tc7-2.1.1.jar
spymemcached-2.11.1.jar
vim /etc/tomcat/context.xml
<Context>
<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"
memcachedNodes="n1:192.168.91.139:11211,n2:192.168.91.137:11211"
lockingMode="auto"
sticky="false"
sessionBackupAsync="false"
sessionBackupTimeout= "1000"
copyCollectionsForSerialization="true"
requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"
transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"
/>
</Context>
yum install -y memcached
systemctl start tomcat memcached
實現前端httpd反代
<proxy balancer://tomcatserver> 定義後端服務器組，名爲tomcatserver
balancermember http://192.168.91.139:8080
balancermember http://192.168.91.137:8080 若是與後端服務器使用ajp協議鏈接，把http改成ajp
proxyset lbmethod=byrequests 至關於輪詢（rr）
</proxy>
<virtualhost *:80>
servername www.magedu.com
proxyrequests off
proxypreservehost on
proxyvia on
<proxy *>
require all granted
</proxy>
proxypass / balancer://tomcatserver/
proxypassreverse / balancer://tomcatserver/
<location />
require all granted
</location>
</virtualhost>
systemctl start httpd
測試
請求輪詢調度到後臺服務器上，Session ID始終不變