You can also configure CloudFront origin failover for scenarios that require high availability. To start, create a source group with two origins: one primary and another secondary. If the primary origin is unavailable or returns specific HTTP response status codes that indicate a failure, CloudFront automatically switches to the secondary origin.
To configure source failover, you must have a distribution with at least two sources. Then create a source group for the distribution that includes two sources, defining one of them as the primary. Finally, create or update a cache behavior to use the origin group.
CloudFront routes all incoming requests to the primary origin, even when a previous request has failed over to the secondary origin. CloudFront only sends requests to the secondary origin after a request fails to the primary origin.
The following diagram shows how source failover works.
CloudFront fails over to secondary origin only when the HTTP method of the consumer request is GET, HEAD, or OPTIONS. CloudFront does not fail over when the consumer sends a different HTTP method (for example POST, PUT, etc.).
Expected RTO: A few seconds depending on the configuration of timeout for connection to origin, number of attempts, and response timeout.