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Running Isolated-worker Azure Function in Docker Container

I’m trying to get an isolated worker model Azure function to run in a container, but it fails with the following error:

Unhandled exception. System.InvalidOperationException: The gRPC channel URI ‘http://:’ could not be parsed.

Here is my dockerfile

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build

WORKDIR /src

COPY ["Email.Function/Email.Function.csproj", "Email.Function/"]
RUN dotnet restore "Email.Function/Email.Function.csproj"

COPY . .

RUN dotnet build "Email.Function/Email.Function.csproj" -c Release -o /app/build

RUN dotnet publish "Email.Function/Email.Function.csproj" -c Release -o /app/publish

FROM mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0

WORKDIR /home/site/wwwroot

COPY --from=build /app/publish .

CMD ["dotnet", "Email.Function.dll", "--dotnet-isolated"]

I saw some workarounds was to add the following environment variables but this also didn’t work

ENV FUNCTIONS_WORKER_GRPC_URI=http://127.0.0.1:5000
ENV WEBSITE_USE_PLACEHOLDER_DOTNETISOLATED=0

I can run and debug the function without using docker, but it fails inside a container.

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2

Answers


  1. 0

    Unhandled exception. System.InvalidOperationException: The gRPC channel URI ‘http://:’ could not be parsed.

    The error could be due to the misconfiguration with the communication between the Azure Functions worker and the runtime.

    I have created a .NET 8.0 Dotnet-isolated Azure function and dockerized the function using the Dockerfile as below:

    Dockerfile:

    # This stage is used when running from VS in fast mode (Default for Debug configuration)

FROM mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0 AS base
WORKDIR /home/site/wwwroot
EXPOSE 8080

# This stage is used to build the service project
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
ARG BUILD_CONFIGURATION=Release
WORKDIR /src
COPY ["FunctionApp/FunctionApp.csproj", "FunctionApp/"]
RUN dotnet restore "./FunctionApp/FunctionApp.csproj"
COPY . .
WORKDIR "/src/FunctionApp"
RUN dotnet build "./FunctionApp.csproj" -c $BUILD_CONFIGURATION -o /app/build

# This stage is used to publish the service project to be copied to the final stage
FROM build AS publish
ARG BUILD_CONFIGURATION=Release
RUN dotnet publish "./FunctionApp.csproj" -c $BUILD_CONFIGURATION -o /app/publish /p:UseAppHost=false

# This stage is used in production or when running from VS in regular mode
FROM base AS final
WORKDIR /home/site/wwwroot
COPY --from=publish /app/publish .
ENV AzureWebJobsScriptRoot=/home/site/wwwroot 
    AzureFunctionsJobHost__Logging__Console__IsEnabled=true

    Docker image for the function:

    4-dotnet-isolated8.0: Pulling from azure-functions/dotnet-isolated
302e3ee49805: Pull complete
fd3debd68516: Pull complete
e31c284582ca: Pull complete
ed4b264aaa40: Pull complete
6abaf3c9f6d3: Pull complete
11f569edae72: Pull complete
dcd258fee610: Pull complete
85cdbb6993b0: Pull complete
e821cb5f22ed: Pull complete
fe23fcab6c1a: Pull complete
Digest: sha256:eeb2724e49f0e7c8c978bd60ee15a2b87714b2376bcc0731af9e09c34385ae1a
Status: Downloaded newer image for mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0
mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0

    Able to run the function in container:

    Azure Functions Core Tools
Core Tools Version:       4.0.6280 Commit hash: N/A +421f0144b42047aa289ce691dc6db4fc8b6143e6 (64-bit)
Function Runtime Version: 4.834.3.22875

[2024-10-14T13:29:31.498Z] Found /home/site/wwwroot/FunctionApp57.csproj. Using for user secrets file configuration.
Skipping 'AzureWebJobsStorage' from local settings as it's already defined in current environment variables.
Skipping 'FUNCTIONS_WORKER_RUNTIME' from local settings as it's already defined in current environment variables.
Skipping 'AzureWebJobsScriptRoot' from local settings as it's already defined in current environment variables.
[2024-10-14T13:29:38.042Z] Extension Bundle not loaded. Loading extensions from /home/site/wwwroot/bin/Debug/net8.0. BundleConfigured: False, PrecompiledFunctionApp: False, LegacyBundle: False, DotnetIsolatedApp: True, isLogicApp: False
[2024-10-14T13:29:38.046Z] Script Startup resetting load context with base path: '/home/site/wwwroot/bin/Debug/net8.0/.azurefunctions'.
[2024-10-14T13:29:38.072Z] Loading startup extension 'Startup'
[2024-10-14T13:29:38.674Z] Loaded extension 'Startup' (1.0.0.0)
[2024-10-14T13:29:40.912Z] Worker indexing is enabled
[2024-10-14T13:29:40.926Z] Fetching metadata for workerRuntime: dotnet-isolated
[2024-10-14T13:29:40.927Z] Reading functions metadata (Worker)
{ "name":"dotnet-worker-startup", "workerProcessId" : 109 }
[2024-10-14T13:29:46.936Z] 1 functions found (Worker)
[2024-10-14T13:29:47.041Z] Azure Functions .NET Worker (PID: 109) initialized in debug mode. Waiting for debugger to attach...
[2024-10-14T13:29:47.200Z] Worker process started and initialized.

Functions:

    Function1: [GET,POST] http://localhost:32047/api/Function1

For detailed output, run func with --verbose flag.
[2024-10-14T13:29:52.541Z] Host lock lease acquired by instance ID '0000000000000000000000004720E01E'.
[2024-10-14T13:30:14.263Z] Executing HTTP request: {

[2024-10-14T13:30:14.263Z]   "requestId": "d2d043f7-de5e-4b5c-be15-ceff675a5e1c",

[2024-10-14T13:30:14.263Z]   "method": "GET",

[2024-10-14T13:30:14.263Z]   "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36",

[2024-10-14T13:30:14.263Z]   "uri": "/api/Function1"

[2024-10-14T13:30:14.263Z] }
[2024-10-14T13:30:14.806Z] Executing 'Functions.Function1' (Reason='This function was programmatically called via the host APIs.', Id=7e0e50d7-cdfb-44d0-966c-bd7cc405a456)
[2024-10-14T13:30:15.688Z] C# HTTP trigger function processed a request.
[2024-10-14T13:30:15.709Z] Executing OkObjectResult, writing value of type 'System.String'.
[2024-10-14T13:30:16.001Z] Executed 'Functions.Function1' (Succeeded, Id=7e0e50d7-cdfb-44d0-966c-bd7cc405a456, Duration=1281ms)
[2024-10-14T13:30:16.108Z] Executed HTTP request: {

[2024-10-14T13:30:16.108Z]   "requestId": "d2d043f7-de5e-4b5c-be15-ceff675a5e1c",

[2024-10-14T13:30:16.108Z]   "identities": "",

[2024-10-14T13:30:16.108Z]   "status": "200",

[2024-10-14T13:30:16.108Z]   "duration": "1841"

[2024-10-14T13:30:16.108Z] }
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  2. 0

    I have a local Docker host running a container with a .NET8 Isolated Azure Functions project. It has HTTP Trigger and Timer Trigger functions.

    My Dockerfile for x64 is as follows:

    FROM mcr.microsoft.com/dotnet/sdk:8.0 AS installer-env

COPY --from=mcr.microsoft.com/dotnet/sdk:8.0 /usr/share/dotnet /usr/share/dotnet

COPY . /src/dotnet-function-app
RUN cd /src/dotnet-function-app && 
    mkdir -p /home/site/wwwroot && 
    dotnet publish ./Your.Api.ProjectName/*.csproj --output /home/site/wwwroot

FROM mcr.microsoft.com/azure-functions/dotnet-isolated:4-dotnet-isolated8.0
ENV AzureWebJobsScriptRoot=/home/site/wwwroot 
    TZ=Europe/London 
    AzureWebJobsStorage= #your storage string

COPY --from=installer-env ["/home/site/wwwroot", "/home/site/wwwroot"]
EXPOSE 80

    In my case I’m running it in a slightly unusual way: in a local Docker host, rather than in Azure. So, it might not be close enough to your environment. But hopefully you can at least take some inspiration from it, if it’s not a perfect match.

    I’ve used this same Dockerfile successfully on local Docker hosts for both x64 and also ARM64v8 on RPi. (although for the latter there’s no official Docker image for .NET8 Isolated, so I’m using a 3rd party one.)

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