Warning when using unsupported worker runtime.

[peterhuene]

I have a local.settings.json file with the following contents:

{
  "IsEncrypted": false,
  "Values": {
    "languageWorkers:workersDirectory": "/Users/peterhuene/src/azure-functions-rs/examples/http/root/workers",
    "FUNCTIONS_WORKER_RUNTIME": "Rust"
  },
  "ConnectionStrings": {}
}

The workers directory exists and has a rust subdirectory with a valid worker config that points to a worker that starts correctly by the Azure Functions host. I can execute functions in this worker without issue.

Despite this, when I use func host start, I immediately get this warning:

your worker runtime is not set. As of 2.0.1-beta.26 a worker runtime setting is required.
Please run `func settings add FUNCTIONS_WORKER_RUNTIME <option>` or add FUNCTIONS_WORKER_RUNTIME to your local.settings.json
Available options: dotnet, node, python

This is because the worker runtime value gets "normalized" and if isn't in the list of supported worker runtimes it results in the warning.

This is terribly confusing to my users as the value is present in the local.settings.json.

I'm fine with perhaps a Language worker runtime 'Rust' is not officially supported. or some such message, but to imply the setting isn't there simply because it isn't a "known value" to the tools can be confounding.

[peterhuene]

This has now turned into a fatal error from the core tools in 2.7.1468:

Can't determin [sic] project langauge from files. Please use one of [--csharp, --javascript, --typescript, --java, --python, --powershell]

Why is the core-tools restricting the runtime worker like this?

[peterhuene]

Closing this as the Azure Functions for Rust project was abandoned.