{"id":222,"date":"2016-01-17T22:36:04","date_gmt":"2016-01-17T20:36:04","guid":{"rendered":"http:\/\/www.systemcodegeeks.com\/?p=222"},"modified":"2016-01-17T22:36:04","modified_gmt":"2016-01-17T20:36:04","slug":"sticky-session-load-balancer-nginx","status":"publish","type":"post","link":"https:\/\/www.systemcodegeeks.com\/web-servers\/nginx\/sticky-session-load-balancer-nginx\/","title":{"rendered":"Sticky Session Load Balancer with Nginx"},"content":{"rendered":"

Load balancer distributes incoming requests across multiple computing application servers. It aims to optimize resource use, maximize throughput, minimize response time, and avoid overload of any single resource.<\/p>\n

Nginx supports below\u00a0load balancing mechanisms:<\/p>\n

    \n
  1. Round-Robin<\/strong> \u2014 Requests to the application servers are distributed in a round-robin fashion.<\/li>\n
  2. Least-Connected<\/strong> \u2014 Next request is assigned to the server with the least number of active connections.<\/li>\n
  3. Ip-Hash<\/strong> \u2014 A hash-function is used to determine what server should be selected for the next request (based on the client\u2019s IP address).<\/li>\n<\/ol>\n

    In this post, we will learn how to configure\u00a0<\/strong>Ip-Hash\u00a0<\/strong>Load Balancing with Nginx<\/a>, following below steps:<\/p>\n

    Step 1:<\/strong> Download Nginx<\/strong> from here<\/a>.<\/p>\n

    Step 2:<\/strong> Unzip the nginx-*.tar.gz<\/strong> and install the it using command:<\/p>\n

    $ cd nginx-1.9.6\r\n$ .\/configure\r\n$ make\r\n$ make install<\/pre>\n
    By default, Nginx will be installed in directory \/usr\/local\/nginx<\/strong>, but Nginx provides the ability to specify a directory where it is to be installed, and same you can do it by providing additional compile option \u2013 \u2013prefix<\/strong>\u00a0as follows:<\/p>\n
    .\/configure --prefix=\/Users\/ArpitAggarwal<\/pre>\n
    For all available compile options use below command:<\/p>\n
    .\/configure --help<\/pre>\n
    Step 3:<\/strong> Start any number of tomcat instances<\/strong> which are a part of a cluster, for me it\u2019s 3 running on a localhost on port 8080<\/strong>, 8081<\/strong>, 8082<\/strong> and define upstream block in \/usr\/local\/nginx<\/strong>\/conf\/nginx.conf<\/strong> file, as follows:<\/p>\n
    upstream cluster-tomcat {\r\n server 127.0.0.1:8080;\r\n server 127.0.0.1:8081;\r\n server 127.0.0.1:8082;\r\n}<\/pre>\n
    Above all requests are proxied to the server group cluster-tomcat<\/strong> in a round-robin fashion and Nginx applies HTTP load balancing to distribute the requests.<\/p>\n
    Step 4:<\/strong> Replace location block under server with below:<\/p>\n
    location \/ {\r\n proxy_pass http:\/\/cluster-tomcat;\r\n}<\/pre>\n
    Step 5:<\/strong> Enable Sticky Session adding ip_hash<\/strong> directive to the server (upstream) group configuration, as follows:<\/p>\n
    upstream cluster-tomcat {\r\n ip_hash;\r\n server 127.0.0.1:8080;\r\n server 127.0.0.1:8081;\r\n server 127.0.0.1:8082;\r\n}<\/pre>\n
    After making changes, complete http block should look like:<\/p>\n
    http {\r\n include mime.types;\r\n default_type application\/octet-stream;\r\n sendfile on;\r\n keepalive_timeout 65;\r\n upstream cluster-tomcat {\r\n  ip_hash;\r\n  server 127.0.0.1:8080;\r\n  server 127.0.0.1:8081;\r\n  server 127.0.0.1:8082;\r\n }\r\n server {\r\n  listen 80;\r\n  server_name localhost;\r\n  location \/ {\r\n    proxy_pass http:\/\/cluster-tomcat;\r\n  }\r\n }\r\n}<\/pre>\n