proxies.json to "Azure API Management" in v4 migration guide? Local execution?

[JasonKleban]

I found this statement that Azure Functions v4 doesn't support proxies.json. Is there an explanation for this change? Is there a migration guide to Azure API Management? Is there a way to run the Azure API Management locally for apps that require the proxy behavior to operate correctly?

I see there is some idea of automatic migration Import an Azure Function App as an API in Azure API Management but I'm weary of even experimenting with changes to even the Dev environment of my Terraform-managed app for fear of corrupting it (could it be 100% undone after collecting the auto-migrated configurations?)

Here is a representation of the various proxies.json features I currently use. Default document, many-to-one resolution, wildcards, external routing, environment variable injection, query parameter passthrough. API Management can do these, and emulate them on the local developer machine?

{
  "$schema": "http://json.schemastore.org/proxies",
  "proxies": {
    "public-default": {
      "matchCondition": {
        "route": "/"
      },
      "backendUri": "http://localhost/api/assets/index.html"
    },
    "public-index": {
      "matchCondition": {
        "route": "/index.html"
      },
      "backendUri": "http://localhost/api/assets/index.html"
    },
    "other_assets": {
      "matchCondition": {
        "route": "/assets/{*any}"
      },
      "backendUri": "http://localhost/api/assets/other/{any}"
    },
    "third_party": {
      "matchCondition": {
        "methods": [ "GET" ],
        "route": "/example/third_party"
      },
      "backendUri": "https://www.example.com?auth=%example_license_key%&query={request.querystring.query}"
    }
  }
}

[v-bbalaiagar]

Tagging @anthonychu , for more inputs

[aiden-liu]

I also see no way of solving this issue locally, however if turning head to API Management (as official recommend) for alternative, can set redirect policy for operation(s), say index, acting like proxy.

<policies>
      <inbound>
          <base />
          <rewrite-uri template="/assets/index.html" />
      </inbound>
      <backend>
          <base />
      </backend>
      <outbound>
          <base />
      </outbound>
      <on-error>
          <base />
      </on-error>
  </policies>

Again, this could be a far simple solution that not apply to all scenarios, as I only dived deep enough to solve my problem.

[JasonKleban]

@anthonychu?

[anthonychu]

For serving static files, better options would be either hosting them in blob storage or using Azure Static Web Apps.

@kulkarnisonia16

[JasonKleban]

Better for whom?

For this application, some assets are dynamic, at least in the sense of a custom security check.

[JasonKleban]

Update your Azure Functions apps to use runtime version 4.x before 3 December 2022

On 3 December 2022, .NET Core 3.1 will be retired. As a result, Azure Functions runtime versions 2.x and 3.x, which use .NET Core 3.1, will also be retired on that date.

Your Functions applications that use runtime version 2.x or 3.x will continue to run and your existing workloads won't be affected. However, we'll no longer provide updates or customer service for applications that use these versions.

This issue is a blocker for Functions v4 adoption.

[JasonKleban]

@kulkarnisonia16 ?

[JasonKleban]

There is still no migration guide that I can find. How can this proxies.json wildcard path prefix redirect be expressed in api_management_api_operation & operation policy?

    "other_assets": {
      "matchCondition": {
        "route": "/assets/{*restOfPath}"
      },
      "backendUri": "http://localhost/api/assets/other/{restOfPath}"
    },

this seems to me to need some kind of support like:

resource "azurerm_api_management_api_operation" "example" {
  ...
  method              = "*"
  url_template        = "/assets/{*restOfPath}"
}

resource "azurerm_api_management_api_operation_policy" "example" {
  ...

  xml_content = <<XML
<policies>
  <inbound>
    <rewrite-uri template="/api/assets/other/{any}" />
    # or perhaps
    <set-backend-service base-url="/api/assets/other/" />
  </inbound>
</policies>
XML

}

but I cannot find documentation or examples on a wildcard method nor a {*restOfPath} concept on url_template. I cannot find relevant documentation on Operation Template Parameters in case it supports a {*restOfPath} analog.

[JesseDeBruijne]

Gonna have to second this issue.

It's weird to recommend that you switch to Azure API Management because it "provides the same capabilities as Functions Proxies" but then provide no migration guide or as @JasonKleban already mentioned not even provide the same capabilities (wildcard forwarding is something I need as well).

[isaacrlevin]

FWIW I added my Function to a new API Management Instance and I have no idea what policies to set. My use case is that I have a UrlShortener that takes a url like this

https://isaacl.dev/presence-light

and transforms it into

https://www.theurlist.com/presencelight

I WAS doing this in Functions v3 with proxies like so

{
  "$schema": "http://json.schemastore.org/proxies",
  "proxies": {
    "Domain Redirect": {
      "disabled": false,
      "matchCondition": {
        "route": "/{*shortUrl}"
      },
      "backendUri": "http://localhost/api/UrlRedirect/{shortUrl}"
    },
    "Api": {
      "disabled": false,
      "matchCondition": {
        "route": "/api/{*path}"
      },
      "backendUri": "http://localhost/api/{path}"
    }
  }
}

I have no idea how to use this with transform policies. If I just test, it doesn't seem to do the rewrite and I just get routed to a fallback url I set in the Function. Some help would be greatly appreciated

[JasonKleban]

Hello? @kulkarnisonia16? @anthonychu? @v-bbalaiagar? Time's ticking toward this December Drop-Dead date. While this is github and open source, it exists solely to support Microsoft's Azure paid platform. Long-term stability of APIs that enable businesses to operate is a crucial responsibility of this product team (I'm not sure if any of the tagged folks are on that team).

Note to that product team - It would be my preference to carry the proxies.json support forward because it is a good and useful tool and you still get paid for it as function executions.

[JesseDeBruijne]

I have now made the switch to an Azure Static Web App for my app. They provide Routing Configuration within the app which was enough to satisfy the needs for my app. It includes stuff like wildcard routing, response headers, URL rewrites/redirects, even Authentication and Authorization.

Maybe it helps someone else.

[vyzvam]

as for the deprecation on December. it is mentioned that "Extended support for .NET Core 3.1 in Azure Functions is retiring on December 3rd 2022" Will i still be able to provision function apps using runtime version 2. My existing apps are still using proxies and expecting to use the same code for new provisioning.

[MacMcDell]

We really need some support on this issue. I have read rumours that proxy support is returning to V4. We need to understand when proxy support is returning. Not being able to test functions/route paths locally is at least for me a show stopper. Can this thread please by updated.

[shambhu-svyc]

As per latest update, proxy can be re-enable usingAzureWebJobsFeatureFlags = EnableProxies see: https://learn.microsoft.com/en-us/azure/azure-functions/legacy-proxies

[jlocans]

Added "AzureWebJobsFeatureFlags": "EnableProxies" to local.settings.json, but now the application won't start.

This is the log I get.

Azure Functions Core Tools
Core Tools Version:       4.0.4895 Commit hash: N/A  (64-bit)
Function Runtime Version: 4.13.0.19486

Warning: Proxies are not supported in Azure Functions v4. Instead of 'proxies.json', try Azure API Management: https://aka.ms/AAfiueq
[2022-11-23T14:47:37.661Z] Found C:\work\my-proj\MyProj.Api\MyProj.Api.csproj. Using for user secrets file configuration.
[2022-11-23T14:47:38.697Z] Unsupported service transport type: . Use default Transient instead.
[2022-11-23T14:47:41.618Z] A host error has occurred during startup operation '30720274-af87-45ce-a08c-1a51d03fa49e'.
[2022-11-23T14:47:41.619Z] Autofac: An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = ProxyHandler (ReflectionActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.ProxyHandler], Lifetime = Autofac.Core.Lifetime.RootScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = ITelemetryListener[] (DelegateActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.Logging.ITelemetryListener[]], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = ExternallyOwned ---> An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = KpiLogService (ReflectionActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.Logging.ITelemetryListener], Lifetime = Autofac.Core.Lifetime.RootScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> An exception was thrown while invoking the constructor 'Void .ctor(Microsoft.Azure.AppService.Proxy.Runtime.Settings)' on type 'KpiLogService'. ---> Could not load file or assembly 'System.Reactive.Core, Version=3.0.3000.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified. (See inner exception for details.) (See inner exception for details.) (See inner exception for details.) (See inner exception for details.). Autofac: An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = ITelemetryListener[] (DelegateActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.Logging.ITelemetryListener[]], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = ExternallyOwned ---> An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = KpiLogService (ReflectionActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.Logging.ITelemetryListener], Lifetime = Autofac.Core.Lifetime.RootScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> An exception was thrown while invoking the constructor 'Void .ctor(Microsoft.Azure.AppService.Proxy.Runtime.Settings)' on type 'KpiLogService'. ---> Could not load file or assembly 'System.Reactive.Core, Version=3.0.3000.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified. (See inner exception for details.) (See inner exception for details.) (See inner exception for details.). Autofac: An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = KpiLogService (ReflectionActivator), Services = [Microsoft.Azure.AppService.Proxy.Runtime.Logging.ITelemetryListener], Lifetime = Autofac.Core.Lifetime.RootScopeLifetime, Sharing = Shared, Ownership = OwnedByLifetimeScope ---> An exception was thrown while invoking the constructor 'Void .ctor(Microsoft.Azure.AppService.Proxy.Runtime.Settings)' on type 'KpiLogService'. ---> Could not load file or assembly 'System.Reactive.Core, Version=3.0.3000.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified. (See inner exception for details.) (See inner exception for details.). Autofac: An exception was thrown while invoking the constructor 'Void .ctor(Microsoft.Azure.AppService.Proxy.Runtime.Settings)' on type 'KpiLogService'. ---> Could not load file or assembly 'System.Reactive.Core, Version=3.0.3000.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified. (See inner exception for details.). Microsoft.Azure.AppService.Proxy.Runtime: Could not load file or assembly 'System.Reactive.Core, Version=3.0.3000.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263'. The system cannot find the file specified.
[2022-11-23T14:47:41.636Z] Failed to stop host instance 'bd4f2f1a-92b7-4121-bf35-99eecdfd8c78'.
[2022-11-23T14:47:41.637Z] Microsoft.Azure.WebJobs.Host: The host has not yet started.
Value cannot be null. (Parameter 'provider')
Press any key to continue....

And it goes in an endless cycle trying to start. I'm also not sure how to target the latest Function Runtime Version. I've specified "FUNCTIONS_EXTENSION_VERSION": "4.15.0" in local settings, but as you can see, it is still using 4.13.0.19486

Can't find which is the version where this is supposed to be fixed either. None of the releases mention anything about proxies.