I have a web page that works in 1 server. We are in progress to migrate to a new plattform that has 3 servers.
In first step in the migration plan we need to pass make a percent, say 10%, to the new cluster and 90% to the old server. The new plattform not needs to have sticky sessions (shares the sessions with memcached).
Is there a way to do that with haproxy?
This can be achieved by having haproxy connect to itself, giving you two tiers of load balancing.
The first listen uses the balance source option and server weights to split the traffic between your existing server and the cluster.
The second tier uses balance roundrobin with no persistence to rotate incoming connection among cluster members.
Listen 10.0.1.1:80
Balance source
Server oldserver 10.0.1.10 weight 90
Server newcluster 10.0.1.20 weight 10
Listen 10.0.1.20:80
Balance roundrobin
Server cluster1 10.0.1.31
Server cluster2 10.0.1.32
Server cluster3 10.0.1.33
balance source does. Once you read up on that, you will understand that a stick table is unnecessary.
You define weights in haproxy to spread the load according to your needs.
From the official haproxy 1.4 documentation:
weight <weight>
The "weight" parameter is used to adjust the server's weight relative to
other servers. All servers will receive a load proportional to their weight
relative to the sum of all weights, so the higher the weight, the higher the
load. The default weight is 1, and the maximal value is 256. A value of 0
means the server will not participate in load-balancing but will still accept
persistent connections. If this parameter is used to distribute the load
according to server's capacity, it is recommended to start with values which
can both grow and shrink, for instance between 10 and 100 to leave enough
room above and below for later adjustments.
Use weight in the haproxy server section. "Weight 1 represents the lowest frequency and 256 the highest"
server newserver1 192.168.1.1:80 weight 3
server newserver2 192.168.1.2:80 weight 3
server newserver3 192.168.1.3:80 weight 3
server oldserver1 192.168.2.1:80 weight 90
