Understand Layer 7 load balancing to route HTTP requests to specialized back-end pools based on application data such as URIs, hostnames, and headers.

You can use the RHOSO Load-balancing service (octavia) with layer 7 policies to redirect HTTP requests to particular application server pools.

Layer 7 (L7) load balancing takes its name from the Open Systems Interconnection (OSI) model, indicating that the load balancer distributes requests to back end application server pools based on layer 7 (application) data.

The following are different terms that all mean L7 load balancing: request switching, application load balancing, and content-based- routing, switching, or balancing. The Red Hat OpenStack Services on OpenShift (RHOSO) Load-balancing service (octavia) provides robust support for L7 load balancing.

An L7 load balancer consists of a listener that accepts requests on behalf of several back end pools and distributes those requests based on policies that use application data to determine which pools service any given request. This allows for the application infrastructure to be specifically tuned and optimized to serve specific types of content. For example, you can tune one group of back end servers (a pool) to serve only images; another for execution of server-side scripting languages such as PHP and ASP; and another for static content such as HTML, CSS, and JavaScript.

Unlike lower-level load balancing, L7 load balancing does not require that all pools behind the load balancing service have the same content. L7 load balancers can direct requests based on URI, host, HTTP headers, and other data in the application message.