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At a high level, load balancing is typically accomplished by having a load balancer or set of load balancers present on a virtual server to a set of clients. This virtual server is backed by a pool of “real” servers that provide some type of resource to those clients. The role of the load balancer is to distribute client requests across the pool of servers including rerouting requests when a member of the pool fails. Clients are not aware which “real” server in the pool are servicing their requests, since they are only aware of the virtual server presented by the load balancer. By leveraging load balancers, client requests can be serviced in such a way as to mitigate against bottlenecks, due to resource contention on any given server or against failed requests due to failures on any given servers. The former use case is what is often considered scaling out while the latter is about creating a fault tolerant service. The canonical example is the use of load balancers in front of a pool of web servers, to serve out web pages to incoming clients via the internet.
Create a Load Balancer
Log in to the OpenStack dashboard.
On the Project tab, open the Network tab, and click the Load Balancers category.
Click the Create Load Balancer button.
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This object representing the grouping of members to which the listener forwards client requests. Note that a pool is associated with only one listener, but a listener might refer to several pools (and switch between them, as we will see later, using layer 7 policies). Assign a name to the Pool and choose the method with which the incoming requests will be distributed. We can choose between 3 algorithms:
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Members may go offline from time to time and health monitors diverts traffic away from members that are not responding properly. Health monitors are associated with pools. We assign a name, choose the HTTP type and, leaving the default values on the other parameters, we create, therefore, our LB.
Associate Floating IP
After creating the LB, we assign a FIP. Then click on Associate Floating IP and, in the screen that appears, select a free FIP to associate with the LB.
Delete a Load Balancer
Log in to the OpenStack dashboard.
On the Project tab, open the Network tab, and click the Load Balancers category.
- Select the load balancer you want to delete and click the Delete Load Balancer button.
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