In this method, all responses from HAProxy to the client will contain a Set-Cookie: header with the name of a backend server as its cookie value.
Install haproxy on kubernetes code#
This code creates a PHP session and displays the number of page views in a single session. We’ll use the following PHP code to demonstrate how session stickiness works. This is possible by tagging each backend server with a cookie. Session stickiness ensures that a visitor sticks on to the VPS which served their first request.
If your web application serves dynamic content based on users’ login sessions (which application doesn’t), visitors will experience odd things due to continuous switching between VPS. Send requests with curl again to see how things work. To see how failover works, go to a web server and stop the service: apache2 stop The client IP we see here is the Private IP address of the load balancer and the X-Forwarded-For header is your IP. Notice here how HAProxy alternatively toggled the connection between LAMP1 and LAMP2, this is how Round Robin works. Now we will use curl and request this file multiple times.
To test this setup, create a PHP script on all your web servers (backend servers - LAMP1 and LAMP2 here). Once you’re done configuring start the HAProxy service: service haproxy start The check option enables health checks on the VPS otherwise, the VPS is There are many paratmeters supported by this directive and we’ll be using the check and cookie parameters in this article. The name we mention here will appear in logs and alerts.
The server directive declares a backend server, the syntax is: server Information about each algorithm can be obtained from the official documentation. Options available are Round Robin ( roundrobin), Static Round Robin ( static-rr), Least Connections ( leastconn), Source ( source), URI ( uri) and URL parameter ( url_param). The balance directive specifies the load balancing algorithm to use. This page can viewed with the URL mentioned in stats uri so in this case, it is a demo of this page can be viewed here. The stats directives enable the connection statistics page and protects it with HTTP Basic authentication using the credentials specified by the stats auth directive. We are configuring HAProxy to listen on port 80 for appname which is just a name for identifying an application. This contains configuration for both the frontend and backend. So session stickness is overriden if a VPS goes down. The option redispatch enables session redistribution in case of connection failures. The retries directive sets the number of retries to perform on a VPS after a connection failure. HAProxy recommends setting the client and server timeouts to the same value. The client and server timeouts apply when the client or server is expected to acknowledge or send data during the TCP process. The connect option specifies the maximum time to wait for a connection attempt to a VPS to succeed. The values to be modified are the various timeout directives. We’re specifying default values in this section. The user and group directives changes the HAProxy process to the specified user/group. The default value is 2000 and should be tuned according to your VPS’ configuration. The maxconn directive specifies the number of concurrent connections on the frontend. We’ll modify the config files of rsyslog later. On Ubuntu rsyslog is already installed and running but it doesn’t listen on any IP address. The log directive mentions a syslog server to which log messages will be sent. Let us begin by adding configuration block by block to this file: global Usage: /etc/init.d/haproxy Ĭreate and edit a new configuration file: nano /etc/haproxy/haproxy.cfg To check if this change is done properly execute the init script of HAProxy without any parameters. We need to enable HAProxy to be started by the init script.
Install haproxy on kubernetes install#
Use the apt-get command to install HAProxy. We will be using three VPS (droplets) here: With DigitalOcean Private Networking, HAProxy can be configured as a front-end to load balance two VPS through private network connectivity. It is particularly suited for HTTP load balancing as it supports session persistence and layer 7 processing. HAProxy(High Availability Proxy) is an open source load balancer which can load balance any TCP service.