Configure Load Balancers


Prerequisites

To follow this guide, you need to create a Load Balancer on your account.

Configure Load Balancer features

The Load Balancer Details page enables you to fine tune behaviors of both the Load Balancer instance and the nodes behind it.

Edit Load Balancer details

Click EDIT DETAILS to display the Edit Load Balancer Details dialog box:

Enter new details dialog box

You can change protocol and port here at any time after the initial build.

You can set a timeout value to control how long the Load Balancer waits for responses from its nodes, with a default of 30 seconds and a maximum of 120 seconds.

You can also change to any of the following algorithms to distribute traffic to the nodes:

  • Round robin: Sends requests to nodes in the order the nodes are listed, with each node treated equally.
  • Weighted round robin: Similar to round robin, except assigns weights to the nodes so that one can receive proportionally more traffic than others.
  • Random: Sends requests to nodes with no regard for the node list order, and treats all nodes equally.
  • Least Connections: Prioritizes nodes with the fewest current connections for new requests.
  • Weighted least connections: Similar to least connections, except assigns weights to the nodes so that one can receive proportionally more traffic than others.

HTTPS redirect allows you to reroute all requests that come to the Load Balancer for HTTP to be rerouted to the HTTPS version of that same URL, returning a 301 Moved Permanently response code. This function only works with HTTPS Load Balancers.

Enable additional features

On the Load Balancer Details page, you can also enable the following additional functions at any time:

  • Content Caching: Enables the load balancer to store frequently accessed content and store it for up to 10 minutes, serving it directly to requesters and therefore reducing the workload of the nodes. Files up to 2MB in size can be cached. Files served from your web servers with a no-cache header are excluded, allowing you to control what is stored.
  • Health Monitoring: Enables either a simple connection or HTTP-based health monitoring service to the nodes. For more help with health monitor configuration and tips on how to use this feature, refer to Load Balancer Health Monitoring.
  • SSL Termination: Sets a load balancer to decrypt HTTPS traffic and pass unencrypted HTTP traffic to the back-end nodes. This feature can only be enabled on HTTP load balancers. For more help on configuring this option, refer to SSL Termination.
  • Custom Error Page: Allows you to set a customized HTML error page for requests that go to an unresponsive node. Disabling the feature after it is set removes all custom content and reverts to the default error page.
  • Session persistence: Enables you to force all requests of the same protocol from one client to the same node, which is commonly used with any applications that are not designed to share their application state among back-end servers. HTTP cookie is available only with HTTP load balancers and inserts a browser-based cookie to identify clients. Source IP is available with HTTPS passthrough load balancers and other non-HTTP protocols and uses the load balancer’s internal services to track the source IP in order to maintain session persistence.

Node options

Use the following additional options to fine-tune how nodes behave when the load balancer serves traffic to them. Click the pencil icon next to any of your Load Balancer’s nodes to bring up the Edit Node Details dialog box, as shown in the following image:

Edit node details dialog box

Condition: Allows for a specified server to handle incoming requests from the Load Balancer differently. The default is enabled and permits all inbound traffic as assigned from the Load Balancer. Setting nodes to disabled immediately stops all requests from going to the node. Setting node condition to draining means that new connections are not sent to the node, but existing sessions are honored. Adding a new node to the Load Balancer with the draining condition set also allows health monitoring to successfully connect to the node, while it still denies inbound traffic.

Weight: Can be used with Load Balancer algorithms with the “weighted” description. Use this value to assign proportionally more traffic to some nodes than others, with a higher number value representing more traffic going to the node.

Node type: Is set to primary by default when you add new nodes. You can configure secondary nodes in this section to redirect traffic to those secondary nodes should all of the primary nodes fail to respond.

Note

To edit the port number that nodes use to receive traffic, delete those nodes from the Load Balancer and re-add them with the desired port.


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