Fallback to the YARP hosted endpoints

[mtamrakar]

I'm trying to use YARP as a means to slowly transition .NET Framework MVC into .NET 7.

The .NET 7 will be the front facing app and the YARP middleware by default proxy everything into the old site at it's inception. This part is working just fine.

As I start rewriting different pages in the .NET 7, I'd like it to NOT redirect those pages. What do I put as a cluster destination for such a setup? Note that the new .NET 7 MVC app and the YARP is being implemented in the same app. We can alternative just have YARP as a separate application but I figured it would more sense to have this setup since we're doing this just for the transition development.

Example of the config I have is below. Here, I have a /home/privacy implemented inside the .NET 7 app that I'd like to go to, as opposed to it getting proxied to the oldsite.com, but I'm not sure what to put as the cluster destination for it

"ReverseProxy": {
    "Routes": {
      "route1": {
        "ClusterId": "cluster1",
        "Match": {
          "Path": "/home/privacy",
          "Order": 1
        }
      },
      "route2": {
        "ClusterId": "cluster2",
        "Match": {
          "Path": "{**catch-all}",
          "Order": 999
        }
      }
    },
    "Clusters": {
      "cluster1": {
        "Destinations": {
          "destination1": {
            "Address": "??"
          }
        }
      },
      "cluster2": {
        "Destinations": {
          "destination1": {
            "Address": "https://oldsite.com"
          }
        }
      }
    }

[MihaZupan]

You should only define routes that you do want to proxy in the YARP config.
By using a lower priority (higher number) for those YARP routes, routing will prefer your local controllers if they exist.

In your case, you should be able to simply remove the cluster1 definition, and let routing pick cluster2 only if that route does not have an implementation in the same project yet.

[mtamrakar]

Yup that was it! route1 was apparently completely unnecessary and anything that's available in the new app would wake the precendence. Thank you!

[cosmoKenney]

Old issue, but I am confused about the same thing. Does route1 stay in place with just the Match property but no "ClusterId"?:

      "route1": {
        "Match": {
          "Path": "/home/privacy",
          "Order": 1
        }
      },

[MihaZupan]

If you define a route with no cluster id, that route will still exist but any requests that match it will return a 503 and log a message about a missing cluster. See #797

[cosmoKenney]

If you define a route with no cluster id, that route will still exist but any requests that match it will return a 503 and log a message about a missing cluster. See #797

Thanks. I still need to figure out how to have local paths in the yarp project. Since the whole point is to incrementally migrate a legacy WebForms site to angular with .net 8.0 for the web api.