Can I access extensions.http.routePrefix at runtime?

[martinjt]

Is there anyway to access to the routePrefix set in host.json at the runtime?

{
    "version": "2.0",
    "extensions": {
      "http": {
        "routePrefix": ""
      }
    }
}

I'm trying to establish the actual route of a HttpTrigger function, which I can't do without the routePrefix as the method's route attribute doesn't include it.

[fabiocav]

@martinjt this information is not made available to the worker today. The simplest way to get this information, today, would be to read the host.json file and get that information directly.

[fabiocav]

Another option is to define the route prefix as an app setting/environment variable (i.e., AzureFunctionsJobHost__extensions__http__routePrefix), and this would be automatically used by the host (no need to define that in host.json) and automatically added as a configuration value in the worker, accessible through IConfiguration

[lmolkova]

I might miss some Functions context, but Isn't it something that ASP.NET Core instrumentation should populate along with http.route ?

[martinjt]

This is specific to functions.

The wider host takes a config that will essentially add a base path to all routes. If you don't supply it, it adds /api/ to what the client would call.

http.route is what I want to populate with the route template from the function, so it get /company/{companyId:int}, and not /company/123 which is http.route vs http.url

When the function has been selected, we can get the attributes and find the route, but that doesn't take into account if someone has passed a routePrefix to the runtime.

[lmolkova]

I believe with this recent change open-telemetry/opentelemetry-specification#3164 introduced in OTel HTTP spec http.route should have it captured.

Once Functions support OTel, I assume it should be possible to update http.route Activity tag to include the prefix.

[martinjt]

This is purely "how do we get the prefix", the attribute is there, we can use it... but I can't get access to the prefix in order to add it to the attrivute.

[lmolkova]

I mean functions can populate the attribute once they support OTel and adopt conventions, but today yes, no way.

[martinjt]

To be clear, I'm not asking for it on an Activity. I'm asking where it exists so that the Runtime can have access to it outside the worker host.

[fabiocav]

Reviewing open items and this is still a gap.

@martinjt are the options I've shared above viable workarounds in the meantime?

[martinjt]

I haven't looked at this recently, however, this wasn't viable at the time. I could look into why though.

[jviau]

@martinjt were you able to see if the proposed workarounds from @fabiocav work for you? Reading from host.json manually or using an appsetting.

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This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment.

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[microsoft-github-policy-service]

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment.

[microsoft-github-policy-service]

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment.