5th February 2016

in Linux

Supporting two default gateways on your Loadbalancer with PBR(Policy Based Routing)

Posted by Aaron West 5th February in Linux

Occasionally we get asked questions about supporting multiple default gateways. Customers may have our appliance in two networks, each with it’s own gateway to the internet. Alternatively it may just be a big complex network with multiple routing paths and stateful devices which are fussy about seeing the whole connection so things get dropped.

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1st November 2013

in HAProxy

3 Ways To Send HAProxy Health Check Email Alerts

Posted by Ben Cabot 1st November in HAProxy

To follow up to Aarons blog on HAProxy emails alerts using logwatch I was looking into different ways to achieve the same results. Now the ideal way to monitor the health of the real servers is to to have a dedicated monitoring system in place such as Nagios( It even has a HAProxy plugin). However this is not always an option for some so they require the loadbalancer to send an alert. So I investigated some different options.

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28th August 2013

in AWS

Load balancing UDP on EC2

Posted by Ben Cabot 28th August in AWS

I had been tasked with finding a way to load balance UDP on AWS. Normally we would use ipvsadm in at layer 4 DR but because of the limitations in ec2 this is not possible so another method was needed. So this is a short guide on how to get a simple UDP load balancer running. We will be using pen, it is described as a simple tcp load balancer and has been around for a while.

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15th August 2013

in HAProxy

Open Source Windows service for reporting server load back to HAProxy (load balancer feedback agent).

Posted by Malcolm Turnbull 15th August in HAProxy

In general when you are load balancing a cluster you can evenly spread the connections through the cluster and you get pretty consistent and even load balancing. However with some applications such as RDS (Microsoft Terminal Servers), you can get very high load from just a  few users doing heavy work. The solution to this is to use some kind of server load feedback agent. We've had one of these for a while in our product but now with a lot of help from Simon Horman we've managed to integrate the functionality into the main branch (well soon anyway) of HAproxy. We thought it would be a good idea to open source the previous work on Ldirectord/LVS, make it compatible with HAProxy, and release our Windows service code as GPL.

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23rd April 2013

in Linux

Look why can’t you just tell me how many people are connected to the load balancer?

Posted by Malcolm Turnbull 23rd April in Linux

I must confess, at certain times it has looked like open warfare would break out between the support team and development team at over the last few months. One reason being that a major change in v7.5 is that all connection information is now displayed as a graph (rather than a static number). The support team was convinced that customers just wanted a number, a single number , a golden number... The development team was convinced that such a number was illogical irrelevant and meaningless.... It will be very interesting to see what the customers think!

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22nd February 2013

in HAProxy

HAProxy Email Alerts Guide

Posted by Aaron West 22nd February in HAProxy

In this guide I show a very simple solution to get HAProxy email alerts configured using Logwatch. While the first part is aimed at users of our V7 appliance I think anyone wanting to get email alerts for HAProxy will also find this a good example.

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12th November 2012

in HAProxy

Setting up HAProxy with Transparent Mode on Centos 6.x

Posted by Andrei Grigoraş 12th November in HAProxy

Transparent mode with HAProxy allows you to see the IP Address of the clients computer while still having a high availability service using HAProxy. This posting shows how to setup a blank virgin installation of Centos 6.3 64bit minimum installation.

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30th May 2012

in Linux

Upstart Script for Collectd

Posted by Mark Brookes 30th May in Linux

We have been doing some internal testing with Collectd. "collectd gathers statistics about the system it is running on and stores this information. Those statistics can then be used to find current performance bottlenecks (i.e. performance analysis) and predict future system load (i.e. capacity planning). Or if you just want pretty graphs of your private server and are fed up with some homegrown solution you're at the right place, too ;)." (taken from their website) Anyway we are quite impressed with it but during the configuration I couldn't locate an upstart script for it so I made my own

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20th July 2009

in HAProxy

Transparent proxy of SSL traffic using Pound to HAProxy backend patch and howto

Posted by Malcolm Turnbull 20th July in HAProxy

OK so I've previously blogged about how to get TPROXY and HAProxy working nicely together. But what if you want to terminate SSL traffic on the load balancer in order to use HaProxy to insert cookies in the standard HTTP stream to the backend servers? Many thanks to Krisztián Ivancsó  for working on the TPROXY patch for Pound for us, we can finally do this!

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13th May 2009

in Linux

How to upgrade VMware tools on ClusterLoad ESX or VA

Posted by Malcolm Turnbull 13th May in Linux

UPDATED November 2014 - Most versions of the appliance come with VMware tools pre-installed by default. These tools enable functions such as controlled OS shutdown, controlled OS restart etc. When installing or updating the tools it's also possible to update various kernel modules and drivers, but this is not recommended by as it can potentially cause issues for the load balancer. Important drivers will be updated as and when necessary via the online or offline software update feature available in the WUI on the appliance.

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11th February 2009

in HAProxy

Configure HAProxy with TPROXY kernel for full transparent proxy

Posted by Malcolm Turnbull 11th February in HAProxy

Standard Kernel builds don't support TPROXY ( 2.6.28 does now!). For example if you use HaProxy as the load balancer then all of the backend servers see the traffic coming from the IP address of the load balancer. TPROXY allows you to make sure the backend servers see the true client IP address in the logs. Ps. An easier alternative is inserting the clients ip in the x-forwarded-for header (option forwardfor). For TPROXY to work you need three things: 1) TPROXY compiled into the linux kernel 2) TPROXY / Socket compiled into netfilter / iptables (due in v1.4.3?) 3) HaProxy compiled with the USE_LINUX_TPROXY option The TPROXY patch for Linux Kernel is here: The following is a guide how to install on Centos 5.1:

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28th July 2008

in Linux

LVS Local node patch for Linux 2.6.25, Centos 5 kernel build how-to

Posted by Malcolm Turnbull 28th July in Linux

Standard Kernel builds of LVS (Linux Vitual Server) don't have the ability to load balance traffic that is from the local node. For example if you terminated some SSL traffic using stunnel or pound on the load balancer you then wouldn't be able to forward that traffic to a backend real server through LVS. First many thanks to Siim Põder for helping to port Carlos Lozano's patch from 2.4 -> 2.6 In order to run an SSL reverse proxy on the same node that is running LVS i.e. External client ---> pound:443 --> Local:443 ---> IPVS:80 ---> RealServer The patch for Linux Kernel 2.6.25 is here: The following is a guide how to install on Centos 5.1:

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