To do this properly, you need to have: Two seperate instances in two datacenters (as you’ve already determined) Synchronisation between the two datacenters (as you’ve already determined) A way of re-directing clients from one to the other in the event of a failure There are two common ways of doing this. One simple, one… not. … Read more
If you have so much load that you need to load balance across two haproxy instances then DNS round robin isn’t a bad idea (I would be surprised if you have this load though). DNS round robin won’t provide good failover though. At Stack Overflow we use heartbeat to provide a single virtual IP, this … Read more
I haven’t tested this specific use case but haproxy does support a “hot reload”: 2.4.1) Hot reconfiguration ————————– The ‘-st’ and ‘-sf’ command line options are used to inform previously running processes that a configuration is being reloaded. They will receive the SIGTTOU signal to ask them to temporarily stop listening to the ports so … Read more
Check out this config: listen my-server 0.0.0.0:80 balance roundrobin server web01 10.10.10.1:80 check inter 10s fall 3 rise 99999999 server web02 10.10.10.2:80 check backup All requests will hit web01 by default. web02 will not be used. If web01 stops responding, after 30s (3 checks at 10 seconds intervals) the server will be taken offline. web02 … Read more
I haven’t experimented with leastconn, but my understanding is that the typical use case for leastconn is when you are load balancing something that can have long lived connections. The reason for this is that leastconn focus on ensuring balanced concurrency where as road robin is going provide a more balanced arrival rate. If this … Read more
We have a similar setup using the HTTP / HTTPS load balancer and we managed to force HTTPS. Its not possible directly from the load balancer but you can set it up from your backend service. The Google Cloud load balancer will set the X-Forwarded-Proto http header with either the value http or https. You … Read more
HAProxy (like many load balancers) generally maintain two conversations. The Proxy has a session (tcp in this case) with the client, and another session with the server. Therefore with proxies you end up seeing 2x the connections on the load balancer. Therefore all traffic flows through the load balancer. When it comes to scaling across … Read more
The most important thing that differentiates the two solutions (LVS, HAproxy) is that one is working at layer 4 (LVS) and the other at layer 7 (HAproxy). Note that the layers references are from OSI networking model. If you understand this, you’ll be able to use one in the right place. For example : if … Read more
http://en.wikipedia.org/wiki/Anycast Anycast is a network addressing and routing methodology in which datagrams from a single sender are routed to the topologically nearest node in a group of potential receivers, though it may be sent to several nodes, all identified by the same destination address. … Nearly all Internet root nameservers are implemented as clusters of … Read more
The distinction between “hardware” and “software” load balancers is no longer meaningful. A so-called “hardware” load balancer is a PC class CPU, network interfaces with packet processing capabilities, and some software to bind it all together. A “software” load balancer realized on a good server with modern NICs is … the same. What you get … Read more