Cloud Bursting using Auto Scale, RackConnect, and F5 Load Balancers


You can use Auto Scale and RackConnect for “cloud bursting”: adding cloud servers dynamically in response to demand, and removing them after they are no longer needed. This article provides information about configuring Auto Scale to use RackConnect to perform cloud bursting with an F5® BIG-IP® Local Traffic Manager (LTM) load balancer. Using these technologies together, you can automatically scale your dedicated infrastructure to the Rackspace cloud by using scaling policies. In this way, RackConnect and Auto Scale enable you to realize the power of the Hybrid Cloud.

The following diagram shows the path that inbound (and return) load balancer pool traffic follows to your cloud servers when you use Auto Scale with a F5 BIG-IP load balancer and RackConnect.


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Configure Auto Scale to use RackConnect to perform cloud bursting

You provision RackConnect for auto scaling by setting a metadata key for a RackConnect load balancer pool in Auto Scale. You set this key in the metadata option of the server argument in the launchConfiguration parameter for scaling groups. When that metadata is set properly and Auto Scale scales up a scaling group, RackConnect modifies new servers to disable their public interface and to enable them to begin receiving your private cloud traffic from the RackConnect load balancer pool. When you delete the cloud servers, they are automatically removed from the load balancer pool.

The metadata key must be RackConnectLBPool. The value for the RackConnectLBPool key must be the exact name of the pool as defined on the load balancer. Use a semicolon-separated list for more than one pool.  Following is an example RackConnect metadata key/value pair for Auto Scale:

"metadata": {
"RackConnectLBPool": "MyRCPoolName"
}

For more information see the Auto Scale API Developer Guide: Set Launch Configuration.

Important notes

When setting metadata for Auto Scale-created servers, consider the following requirements:

  • Verify that an appropriate health check has been configured for members of the load balancer pool or pools being used. The health check should confirm that the website or application is fully ready to accept end-user traffic, because the cloud server might be added almost immediately after creation but before your application is ready to accept traffic, depending on the timing of the automation. For example, it would be advisable to use a URL content check instead of a TCP port check to confirm that a web application is ready to accept end-user requests.
  • The service port for each member of the load balancer pool must match or the automation will not be able to determine which service port to use. For this same reason, there should always be at least one member in the pool. If a common service port cannot be determined, a notification will be routed to your Support team for manual intervention.
  • To learn more about cloud bursting see Using Dedicated Load Balancers with RackConnect.

To get the name of one or more load balancer pools, contact your Support team.



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