Premise: you need to install java first. Essence: a program running on the java virtual machine

Function: tomcat is a web application server, which runs java programs in tomcat and returns the program results to users in the form of web. The user access results come from the execution results of java; nginx and Apache are static servers, but java does not support them;

Note: after upgrading the web page, you need to clear the cache and save it in the jsp folder with deep work

Root directory structure of tomcat:

Installation path: / usr/local/tomcat/webapps/ROOT

tomcat will think that each directory under webapps is a separate java application, so the ROOT and

Profile:

When modifying a sub configuration file, you need to pay attention to the attributes of the file and modify the group and owner

Implementing tomcat deployment with reverse proxy

nginx+tomcat

tomcat load balancing

Session hold mode:

Session stickiness:

Based on the of session and cookie, the same machine that provides services uniformly is scheduled

session replication: the multicast cluster provided by Tomcat synchronizes the sessions of any server to other nodes through multicast.

shortcoming

There should not be too many synchronization nodes in Tomcat. Mutual instant messaging synchronization sessions require too much bandwidth; Each has all sessions, and the memory consumption is too much

The configuration needs to be modified in two places

Session shared server: memcached and redis are used as shared session servers

memcached: small cache server

Session problem solution summary

1. session binding, based on IP or session cookie. Its deployment is simple, especially based on session stickiness, with small granularity and little impact on load balancing. However, once the back-end server fails, the session on it will be lost.

2. session replication cluster, sharing and synchronizing all sessions in multiple servers based on tomcat. This method can ensure that any back-end server fails, and all sessions are stored on other servers, which has no impact on the business. However, it implements heartbeat based on multicast and replication based on TCP unicast. When there are too many device nodes, this replication mechanism is not a good solution. And when there are many concurrent connections, the memory space occupied by all sessions on the single machine is very huge, or even runs out of memory.

3. The session server stores all sessions in a shared memory space and uses multiple redundant nodes to save sessions, so that the session storage server is highly available and occupies less memory of the business server. It is a better solution for session persistence.

However, the above methods all realize the preservation of session in memory. You can use the database or file system to store and persist the session data. In this way, the session data can also be restored after the server is restarted. However, session data is time sensitive. Whether this is necessary depends on the situation

Experiment: tomcat based high availability + nginx (haproxy) reverse proxy + session server memcached (redis)

Experiment planning:

Tomcat binary installation tomcat1 and tomcat2:

yum -y install java-1.8.0-openjdk.x86_64 java-1.8.0-openjdk-devel

wget http://mirrors.tuna.tsinghua.edu.cn/apache/tomcat/tomcat-8/v8.5.50/bin/apache-tomcat-8.5.50.tar.gz

tar xvf apache-tomcat-8.5.64.tar.gz -C /usr/local/ 

cd /usr/local/

#Specify the PATH variable

ln -s apache-tomcat-8.5.64/ tomcat

echo 'PATH=/usr/local/tomcat/bin:$PATH' > /etc/profile.d/tomcat.sh

. /etc/profile.d/tomcat.sh

useradd -r -s /sbin/nologin tomcat

cat > /usr/local/tomcat/conf/tomcat.conf << EOF

#Set at least one of the two variables to start tomcat. This line is to point out the java path. If yum is installed, use the following path:

JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.181-7.b13.el7.x86_64/

#JAVA_HOME=/usr/local/jdk

#JRE_HOME=/usr/local/jdk/jre

EOF

chown -R tomcat.tomcat /usr/local/tomcat/

#Create Tomcat Service file

cat > /lib/systemd/system/tomcat.service << EOF

[Unit]

Description=Tomcat

After=syslog.target network.target 

[Service]

Type=forking

EnvironmentFile=/usr/local/tomcat/conf/tomcat.conf

ExecStart=/usr/local/tomcat/bin/startup.sh

ExecStop=/usr/local/tomcat/bin/shutdown.sh

PrivateTmp=true

User=tomcat

Group=tomcat

[Install]

WantedBy=multi-user.target

EOF

systemctl daemon-reload

systemctl enable --now tomcat.service

Install tomcat2 in the same situation

nginx+tomcat realizes dynamic and static separation:

tomcat is installed;

yum install nginx -y

#Add 3 pages

echo /usr/local/tomcat/webapps/ROOT/tomcat1_static.html >/usr/local/tomcat/webapps/ROOT/test.html

echo /usr/local/tomcat/webapps/ROOT/tomcat1_dynamic.jsp >/usr/local/tomcat/webapps/ROOT/test.jsp

echo nginx1 > /usr/share/nginx/html/test.html

vim /etc/nginx/nginx.conf

#Add three lines below

location ~* \.jsp$ {

proxy_pass http://127.0.0.1:8080; 

}

curl 192.168.37.105/test.html

curl 192.168.37.105/test.jsp

nginx enables load balancing:

vim /etc/nginx/nginx.conf

#Add the following statement block:

upstream tomcat-server {

#ip_hash; 

server t1.lijian.com:8080;

server t2.lijian.com:8080;

}

location ~* \.(jsp|do)$ {

proxy_pass http://tomcat-server;

}

systemctl restart nginx

Configure the hosts file on agent 103

vim /etc/hosts

192.168.37.105 t1.lijian.com t1

192.168.37.106 t2.lijian.com t2

Install and configure memcached on tomcat1:

yum install memcached -y

Check the configuration file and there is no problem

cat /etc/sysconfig/memcached 

PORT="11211"     #Listening port

USER="memcached" #Start user

MAXCONN="1024"  #maximum connection

CACHESIZE="64"  #Maximum memory used

OPTIONS="-l 127.0.0.1,::1" #Other options

modify tomcat1 Profile:

vim /usr/local/tomcat/conf/server.xml

#Modify default page

<Engine name="Catalina" defaultHost="www.lijian.com">

#Configuring virtual machines

<Host name="www.lijian.com" appBase="/data/webapps"

unpackWARs="true" autoDeploy="true">

</Host>

#To create a test page:

vim /data/webapps/ROOT/index.jsp

<%@ page import="java.util.*" %> 

<!DOCTYPE html>

<html lang="en">

<head>

  <meta charset="UTF-8">

  <title>tomcat test</title>

</head>

<body>

<div>On <%=request.getServerName() %></div>

<div><%=request.getLocalAddr() + ":" + request.getLocalPort() %></div>

<div>SessionID = <span style="color:blue"><%=session.getId() %></span></div>

<%=new Date()%>

</body>

</html>

#Modify permissions

chown -R tomcat.tomcat /data/webapps/

The test session is changing:

#sticky mode configuration msm

vim /usr/local/tomcat/conf/context.xml

###Before the penultimate line, i.e</Context>Front of line,Add the following

<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"

memcachedNodes="n1:192.168.37.105:11211,n2:192.168.37.106:11211"                     

failoverNodes="n1"

requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"

transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"

/>

#Related packages to/usr/local/tomcat/lib lower

asm-5.2.jar

kryo-3.0.3.jar

kryo-serializers-0.45.jar

memcached-session-manager-2.3.2.jar

memcached-session-manager-tc8-2.3.2.jar

minlog-1.3.1.jar

msm-kryo-serializer-2.3.2.jar

objenesis-2.6.jar

reflectasm-1.11.9.jar

spymemcached-2.12.3.jar

tomcat2 Configuration of: according to tomcat to configure

#Configure msm

vim /usr/local/tomcat/conf/context.xml

###Before the penultimate line, i.e</Context>Front of line,Add the following

<Manager className="de.javakaffee.web.msm.MemcachedBackupSessionManager"

memcachedNodes="n1:192.168.37.105:11211,n2:192.168.37.106:11211"                     

failoverNodes="n2"

requestUriIgnorePattern=".*\.(ico|png|gif|jpg|css|js)$"

transcoderFactoryClass="de.javakaffee.web.msm.serializer.kryo.KryoTranscoderFactory"

/>

#non-sticky Mode configuration msm

#Based on the previous experiments, the memcached configuration remains unchanged, and only the tomcat configuration needs to be modified

sticky="false"

sessionBackupAsync="false"

lockingMode="uriPattern:/path1|/path2"

Test:

redis cache

yum -y install redis

sed -i.bak 's/^bind.*/bind 0.0.0.0/' /etc/redis.conf

systemctl enable --now redis

#And non-sticky of memcached comparison,Modify this row only

vim /usr/local/tomcat/conf/context.xml 

memcachedNodes="redis://10.0.0.103:6379"