Blazor WASM build unable to find `python` in $PATH on CBL Mariner 2.0 with .NET 6

[lbussell]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

The emsdk fails to build the blazorwasm template using the wasm-tools workload on CBL Mariner 2.0 and .NET 6.0 because it cannot find python on the $PATH.

Expected Behavior

The build is successful.

Steps To Reproduce

Build the following Dockerfile:

FROM mcr.microsoft.com/dotnet/sdk:6.0-cbl-mariner2.0

ARG TARGETARCH

WORKDIR /source

RUN . /etc/os-release \
    && case $ID in \
        alpine) apk add --no-cache python3 ;; \
        debian | ubuntu) apt-get update \
            && apt-get install -y --no-install-recommends python3 \
            && rm -rf /var/lib/apt/lists/* ;; \
        mariner) tdnf install -y python3 \
            && tdnf clean all ;; \
        esac \
    && dotnet workload install --skip-manifest-update wasm-tools

RUN dotnet new blazorwasm -o app --no-restore

WORKDIR /source/app

RUN dotnet restore -r linux-x64

RUN dotnet build --no-restore

RUN dotnet publish -r linux-x64 -c Release --self-contained true -o out

Try out 7.0/8.0 in the FROM instruction and see that it works for .NET versions > 6.0. Other operating systems also work with this Dockerfile.

Exceptions (if any)

The error presents as an issue with emcc:

/usr/share/dotnet/packs/Microsoft.NET.Runtime.WebAssembly.Sdk/6.0.5/Sdk/WasmApp.Native.targets(429,5): error MSB3073: The command "emcc --version" exited with code 1. [/source/app/app.csproj]

Enabling diagnostic output then reveals the actual error:

emcc --version (TaskId:227)
unable to find python in $PATH (TaskId:227)

python3 is installed on Mariner 2.0. Other distros alias python > python3, but not Mariner 2.0. I am guessing this is a fix that didn't get backported to .NET 6.0?

.NET Version

SDK 6.0.418, Runtime 6.0.26

Anything else?

I also found this similar PR: dotnet/emsdk#19

[wtgodbe]

Looks like this should be moved to emsdk

[wtgodbe]

@radical who owns EMSDK these days?

[radical]

Cc @lewing

[wtgodbe]

@lewing should the issue be moved to https://github.com/emscripten-core/emsdk? I see that https://github.com/dotnet/emsdk doesn't have an Issues section

[wtgodbe]

Moved to runtime as that's closer to EMSDK than aspnetcore is

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

The emsdk fails to build the blazorwasm template using the wasm-tools workload on CBL Mariner 2.0 and .NET 6.0 because it cannot find python on the $PATH.

Expected Behavior

The build is successful.

Steps To Reproduce

Build the following Dockerfile:

FROM mcr.microsoft.com/dotnet/sdk:6.0-cbl-mariner2.0

ARG TARGETARCH

WORKDIR /source

RUN . /etc/os-release \
    && case $ID in \
        alpine) apk add --no-cache python3 ;; \
        debian | ubuntu) apt-get update \
            && apt-get install -y --no-install-recommends python3 \
            && rm -rf /var/lib/apt/lists/* ;; \
        mariner) tdnf install -y python3 \
            && tdnf clean all ;; \
        esac \
    && dotnet workload install --skip-manifest-update wasm-tools

RUN dotnet new blazorwasm -o app --no-restore

WORKDIR /source/app

RUN dotnet restore -r linux-x64

RUN dotnet build --no-restore

RUN dotnet publish -r linux-x64 -c Release --self-contained true -o out

Try out 7.0/8.0 in the FROM instruction and see that it works for .NET versions > 6.0. Other operating systems also work with this Dockerfile.

Exceptions (if any)

The error presents as an issue with emcc:

/usr/share/dotnet/packs/Microsoft.NET.Runtime.WebAssembly.Sdk/6.0.5/Sdk/WasmApp.Native.targets(429,5): error MSB3073: The command "emcc --version" exited with code 1. [/source/app/app.csproj]

Enabling diagnostic output then reveals the actual error:

emcc --version (TaskId:227)
unable to find python in $PATH (TaskId:227)

python3 is installed on Mariner 2.0. Other distros alias python > python3, but not Mariner 2.0. I am guessing this is a fix that didn't get backported to .NET 6.0?

.NET Version

SDK 6.0.418, Runtime 6.0.26

Anything else?

I also found this similar PR: dotnet/emsdk#19

Author:	lbussell
Assignees:	-
Labels:	arch-wasm, untriaged, needs-area-label
Milestone:	-