Fusion gateway schema hot reload not working with ConfigureFromFile

[interad-woergoetter]

Is there an existing issue for this?

• I have searched the existing issues

Product

Hot Chocolate

Describe the bug

When I configure my fusion gateway server from a file, changes to the file don't take effect until the server is restarted.

services
    .AddFusionGatewayServer()
    .ConfigureFromFile("gateway.fgp", watchFileForUpdates: true)

The issue occurred in version 13.5.1. After downgrading to 13.2.1, when the configuration looked slightly differently, hot reload worked without needing to restart.

Steps to reproduce

1. Set up a HotChocolate Fusion gateway server with services.AddFusionGatewayServer().ConfigureFromFile("gateway.fgp", watchFileForUpdates: true).
2. Create a valid gateway.fgp file.
3. Start the GraphQL Fusion server.
4. Confirm in BananaCakePop that the schema was loaded correctly from the gateway.fgp file.
5. Replace the gateway.fgp file with a different valid configuration.
6. Reload the schema in BananaCakePop and notice that the schema hasn't changed.
7. Restart the GraphQL Fusion server.
8. Confirm that BananaCakePop now shows the new schema.

Relevant log output

No response

Additional Context?

.ConfigureFromCloud() seems to work. So I assume the error might be related to the file watcher.

Version

13.5.1

[jeroenbongers]

Just wanted to add that we have the same issue. I can even delete the gateway.fgp file and it keeps working.

However if I restart it after deleting the file it can't load the schema, so I'm sure that the same file is being loaded and the correct directory is being used.

[furystormss]

@michaelstaib any update on this? This problem has been in the package since sep 2023, was wondering when this will be scheduled or fixed.

Right now I don't think there is any out of the box way to make it work, exect for the hochocolate cloud or by restarting the entire gateway every time.

[interad-woergoetter]

Right now I don't think there is any out of the box way to make it work, exect for the hochocolate cloud or by restarting the entire gateway every time.

@furystormss for us, we decided that restarting the gateway is a sufficient workaround until someone gets around to fixing the bug.
As far as I know, hot reloading works on Mac, but not on Windows. So switching OS could fix it for you xD

If that is not an option for you, you can implement your own file watcher and use the ConfigureFromDocument() method instead of ConfigureFromFile() You can use ChilliCreams implementation of the https://github.com/ChilliCream/graphql-platform/blob/14.3.0/src/HotChocolate/Fusion/src/Core/DependencyInjection/GatewayConfigurationFileObserver.cs as inspiration. Just be aware that the bug causing this issue is also somewhere in that class or its dependencies, I think 😅
Although, now that I think about it, the bug could also be somewhere else in which case, writing your own file watcher and registering it with ConfigureFromDocument wouldn't even help.

I heard HC v15 will come with a lot of changes for Fusion. Maybe this will be fixed too.