How CBS Sports Digital Leverages Fastly Media Shield
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Taylor Busch: Media Shield is a Fastly product that sat in front of the AWS origins, and it's essentially another caching layer, but it has a number of advantages. And this is actually where quite a bit of the magic happened as far as our ability to you know, provide failovers and whatnot.
So, we had Fastly Media Shield and we also had CloudFront as a backup, because we didn't want to have Media Shield as a single point of failure. If we did have a problem with it, we'd be able to switch to CloudFront and it would all basically work the same way. So, we had two different implementations.
On the Fastly side it was VCL, Varnish Configuration Language, and on the CloudFront side it was the Lambda at Edge. But they're essentially functionally equivalent, doing the same things. And so what it does is when requests come in to the Media Shield we look at things like, "Okay, is the manifest within a certain TTL?" Because, for example, if the encoder stops outputting or if there's network latency, if it dies, if there's some issue, then we know that the content that we're trying to request is gonna be old, right?
So we do that test and we obviously do a test for unhealthy backends in general, right? So, if there's an error retrieving any of the content from the origin we can automatically fail over and try another origin. I think this is a great solution because we had done some testing with putting more of this failover onto the client. So, you know, we extensively tried to pay with advertising more of the available streams in the actual manifest and then simulating issues where the video player would be forced to switch between the different streams.
What we found is every client was a little bit different, we couldn't find the consistency there where we had a clear cause and effect--if this particular platform is forced to switch versus another platform, we weren't able to guarantee the same result. But here this was all obviously invisible to the player. So, you know, we had a extremely simple manifest and all of this was able to happen under the hood seamlessly.
A lot of the testing we would do here would be around origins, you know. For example, turning off a particular origin and having it fail over to another, turning off a region, you know, stopping an output on an encoder to force staleness, things of that nature. You know, we extensively tested this in order to make sure that this was working.
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