Shulou(Shulou.com)06/02 Report--

Preface

Nginx+Tomcat has always known about the management of Session, but has never done it again. This article starts from the simplest installation startup, and introduces several ways to manage session step by step through examples.

Nginx installation configuration

1. Install nginx

[root@localhost ~] # yum install nginx

Prompt to report the following error:

No package nginx available.

Solution installation epel:EPEL is short for Enterprise Linux add-on package. EPEL is a high-quality add-on package project for Red Hat Enterprise Linux (RHEL) and its derivative distributions (such as CentOS, Scientific Linux, Oracle Enterprise Linux) created, maintained and managed by the Fedora special interest group.

[root@localhost ~] # yum install epel-release

After the installation, you can successfully install nginx

two。 Start and stop nginx

Enter the directory of nginx first.

[root@localhost nginx] # cd / usr/sbin/

Execute a command

. / nginx open. / nginx-s stop uses the kill command to force the killing of the process. / nginx-s quit stops when the nginx process finishes processing the task. / nginx-s reload

Nginx+tomcat load balancing

1. Prepare 2 tomcat with designated port of 8081 and 8082 respectively

Drwxr-xr-x. 9 root root 4096 May 7 14:16 apache-tomcat-7.0.88_8081drwxr-xr-x. 9 root root 4096 May 7 14:16 apache-tomcat-7.0.88_8082

Modify the index.jsp of webapps/ROOT to facilitate testing

SessionID:

SessionCreateTime:

The final output specifies the respective port numbers 8081 and 8082 under the two tomcat

2.nginx configure load balancing (default policy)

Modify the nginx.conf under / etc/nginx/

Upstream tomcatTest {server 127.0.0.1 server 8081; # tomcat-8081 server 127.0.0.1 tomcat-8081 server 8082; # tomcat-8082} server {listen 80 [:]: 80 default_server; server_name _; root / usr/share/nginx/html; # Load configuration files for the default server block. Include / etc/nginx/default.d/*.conf; location / {proxy_pass http://tomcatTest;} error_page 404 / 404.html; location = / 40x.html {} error_page 500502503504 / 50x.hml; location = / 50x.html {}}

The load balancing policy configured here is the default polling policy. Other policies supported by nginx include: ip_hash, weight, fair (third party), url_hash (third party)

The default policy is that each web request is assigned to a different backend server one by one in chronological order. In this case, a new session is created for each request. Here is a simple test:

Request http://ip/ for the first time

Key is null,ready init. SessionID:E7A9782DED29FF04E21DF94078CB4F62 sessionCreateTime:1527732911441tomcat port 8082

Refresh http://ip/ for the second time

Key is null,ready init. SessionID:7812E8E21DBB74CC7FBB75A0DFF2E9CB sessionCreateTime:1527732979810tomcat port 8081

Refresh http://ip/ for the third time

Key is null,ready init. SessionID:8895F41E299785A21995D5F8BB734B86 sessionCreateTime:1527733011878tomcat port 8082

It can be found that a new session is generated each time, and messages are distributed to different back-end servers one by one in chronological order. Websites that generally need to maintain session sessions are not allowed to generate a session for each request.

3.nginx configure load balancer (sticky Session)

Each request is allocated according to the hash result of accessing the ip, so that each visitor accesses a back-end server regularly, which can solve the session problem. Nginx can implement sticky Session by configuring ip_hash in the upstream module.

Upstream tomcatTest {ip_hash; server 127.0.0.1 tomcat-8081 server 8081; # tomcat-8081 server 127.0.0.1 virtual 8082; # tomcat-8082}

Here's a simple test:

Request http://ip/ for the first time

Key is null,ready init. SessionID:859BADFB09A4ECEAEC5257F518C228A0 sessionCreateTime:1527734181450tomcat port 8081

Refresh http://ip/ for the second time

Key is not null,key=value sessionID:859BADFB09A4ECEAEC5257F518C228A0 sessionCreateTime:1527734181450tomcat port 8081

Refresh http://ip/ for the third time

Key is not null,key=value sessionID:859BADFB09A4ECEAEC5257F518C228A0 sessionCreateTime:1527734181450tomcat port 8081

You can find that the key=value is set for the first request, and then the key value can be obtained every time. The sessionId and tomcat have not changed, and the sticky Session has been realized.

At this point, you can stop the tomcat of port=8081, and then observe

Refresh http://ip/ for the fourth time

Key is null,ready init. SessionID:3C15FE2C8E8A9DCDC6EAD48180B78B80 sessionCreateTime:1527735994476tomcat port 8082

Refresh http://ip/ for the fifth time

Key is not null,key=value sessionID:3C15FE2C8E8A9DCDC6EAD48180B78B80 sessionCreateTime:1527735994476tomcat port 8082

You can find that the message was forwarded to tomcat-8082, and the session was lost, and a new session was recreated.

There are two ways to make sure that session is not lost in this situation: Session replication and Session sharing; Session sharing is better in terms of scalability and performance.

The following focuses on how to implement Session sharing

Session sharing based on nginx+tomcat

The idea of Session sharing is to save session to a public place, and then take it out of it when you use it. The specific common place can be: redis,db,memcached, etc. The following is redis as an example

1.redis installation configuration

Yum install redis

Configuration file / etc/redis.conf after installation is complete

Start the redis server

Redis-server / etc/redis.conf

Start the client

Redis-cli

2.Tomcat introduces dependent jar

$TOMCAT_HOME/lib add the following jar package

Com.bluejeans tomcat-redis-session-manager 2.0.0 redis.clients jedis 2.5.2 org.apache.commons commons-pool2 2.2

3.Tomcat modifies configuration

Modify the context.xml file in the $TOMCAT_HOME/conf directory

Tomcat provides an open session management and persistent org.apache.catalina.session.ManagerBase. Inheriting this abstract class and doing some simple configuration, you can let your session management class take over the session reading and persistence of Tomcat. Here, tomcat-redis-session-manager is used to manage session.

RedisSessionManager inherits from the org.apache.catalina.session.ManagerBase class, and the related operations on session are all in this class.

4. test

Request http://ip/ for the first time

Key is null,ready init. SessionID:1131499E5A65DE1591152465E7B24B1F sessionCreateTime:1527740273682tomcat port 8081

Refresh http://ip/ for the second time

Key is not null,key=value sessionID:1131499E5A65DE1591152465E7B24B1F sessionCreateTime:1527740273682tomcat port 8081

Stop tomcat-8081 and refresh http://ip/ for the third time

Key is not null,key=value sessionID:1131499E5A65DE1591152465E7B24B1F sessionCreateTime:1527740273682tomcat port 8082

You can find that the message has been forwarded to the tomcat-8082 node, but the session has not changed, and the key can get the value.

5. View redis

[root@localhost ~] # redis-cli127.0.0.1:6379 > keys * 1) "1131499E5A65DE1591152465E7B24B1F" 127.0.0.1 keys 6379 > get 1131499E5A65DE1591152465E7B24B1F "\ xac\ xed\ X00\ x05sr\ x00Dcom.orangefunction.tomcat.redissessions.SessionSerializationMetadataB\ xd9\ xf7v\ xa2\ xdbL\ x03\ X01 [Bxpw\ x14\ x00\ x10}\ xc8\ xc9\ xcf\ xc3\ xb5Y\ xc7\ X0c\ x8eF\ xa5\ xfaQ\ xe8xsr\ X00\ x0ejava.lang.Long \ x8b\ xe4\ x90\ xcc\ x8f#\ xdf\ X00\ x01J\ X00\ x05valuexr\ X00\ x10java.lang.Number\ x86\ xac\ x95\ x1d\ x94\ xe0\ x8b\ x02\ x00xp\ X00\ X01c\ xb4j\ X00c\ X003\ X00\ x01c\ xb4j\ x94\ x12sr\ x11java.lang.Integer\ X12\ xe2\ xa0\ xa4\ xf7\ x81\ x878\ X02\ x01I\ x00\ x05valuexq\ x001c X04\ X00\ a\ bsr\ X00\ x11java.lang.Boolean\ xcd r\ X80\ xd5\ X9c\ xfa\ xee\ X02\ x05valuexp\ x01q\ x00~\ X00\ nsq\ X003\ x00\ x01c\ xb4j\ x94t\ X00 1131499E5A65DE1591152465E7B24B1Fsq\ X00~\ X00\ a\ X00\ X00\ X01t\ x03keyt\ X00\ x05valuew\ b\ X00\ X01c\ xb4j\ x94\ x12 "

You can find that session objects have been stored in redis, and sessionId is used as the key value to store the binary data of session.

Summary

This article briefly introduces the integration of Tomcat with Nginx and the load balancing strategy of Nginx, and demonstrates the management of session by default policy and ip_hash policy by an example. Finally, it introduces the use of session sharing to solve the disadvantages of the first two ways of session management. In the future, we will continue to learn how Tomcat transfers session reading and persistence to other systems, whether session updates are real-time, serialization scheme, validity period and so on.

The above is the whole content of this article, I hope it will be helpful to your study, and I also hope that you will support it.

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