Provide MUSL-based build

Fixes #408

Author: cretz

.github/workflows/package.yml

@@ -1,5 +1,6 @@
 name: Build Package
 on:
+  pull_request:
   push:
     branches:
       - main
@@ -10,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, ubuntu-arm, macos-intel, macos-arm, windows-latest]
+        os: [ubuntu-latest, ubuntu-arm, alpine-latest, macos-intel, macos-arm, windows-latest]
         include:
           - os: ubuntu-latest
             out-file: libtemporal_sdk_bridge.so
@@ -25,6 +26,13 @@ jobs:
             # We use the Python manylinux image for glibc compatibility
             container: quay.io/pypa/manylinux2014_aarch64
             protobuf-url: https://github.com/protocolbuffers/protobuf/releases/download/v22.3/protoc-22.3-linux-aarch_64.zip
+          - os: alpine-latest
+            out-file: libtemporal_sdk_bridge.so
+            out-prefix: linux-musl-x64
+            # Need Alpine container since GH runner doesn't have one
+            container: mcr.microsoft.com/dotnet/sdk:8.0-alpine
+            protobuf-url: https://github.com/protocolbuffers/protobuf/releases/download/v22.3/protoc-22.3-linux-x86_64.zip
+            runsOn: ubuntu-latest
           - os: macos-intel
             out-file: libtemporal_sdk_bridge.dylib
             out-prefix: osx-x64
@@ -68,8 +76,8 @@ jobs:
         if: ${{ !matrix.container }}
         run: cargo build --manifest-path src/Temporalio/Bridge/Cargo.toml --release
 
-      - name: Build (Docker)
-        if: ${{ matrix.container }}
+      - name: Build (Docker non-Alpine)
+        if: ${{ matrix.container && matrix.os != 'alpine-latest' }}
         run: |
           docker run --rm -v "$(pwd):/workspace" -w /workspace \
             ${{ matrix.container }} \
@@ -82,6 +90,22 @@ jobs:
              && cargo build --manifest-path src/Temporalio/Bridge/Cargo.toml --release \
             '
 
+      - name: Build (Docker Alpine)
+        if: ${{ matrix.container && matrix.os == 'alpine-latest' }}
+        run: |
+          docker run --rm -v "$(pwd):/workspace" -w /workspace \
+            ${{ matrix.container }} \
+            sh -c ' \
+                curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain stable -y \
+             && . $HOME/.cargo/env \
+             && rustup target add x86_64-unknown-linux-musl \
+             && apk add --no-cache build-base musl-dev musl-gcc \
+             && curl -LO ${{ matrix.protobuf-url }} \
+             && unzip protoc-*.zip -d /usr/local/protobuf \
+             && export PATH="$PATH:/usr/local/protobuf/bin" \
+             && cargo build --manifest-path src/Temporalio/Bridge/Cargo.toml --release --target x86_64-unknown-linux-musl \
+            '
+
       - name: Upload bridge library
         uses: actions/upload-artifact@v4
         with:
@@ -129,15 +153,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, ubuntu-arm, macos-intel, macos-arm, windows-latest]
+        os: [ubuntu-latest, ubuntu-arm, alpine-latest, macos-intel, macos-arm, windows-latest]
         include:
           - os: ubuntu-arm
             runsOn: buildjet-4vcpu-ubuntu-2204-arm
+          - os: alpine-latest
+            container: mcr.microsoft.com/dotnet/sdk:8.0-alpine
           - os: macos-intel
             runsOn: macos-13
           - os: macos-arm
             runsOn: macos-14
     runs-on: ${{ matrix.runsOn || matrix.os }}
+    container: ${{ matrix.container }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -151,6 +178,7 @@ jobs:
           path: nuget-package
 
       - name: Setup .NET
+        if: ${{ !matrix.container }}
         uses: actions/setup-dotnet@v4
         with:
           # Specific .NET version required because GitHub macos ARM image has

README.md

@@ -815,6 +815,8 @@ reimplementation of the Temporal server with special time skipping capabilities.
 to run when first called. Note, this class is not thread safe nor safe for use with independent tests. It can be reused,
 but only for one test at a time because time skipping is locked/unlocked at the environment level.
 
+⚠️ WARNING - at this time, the time-skipping test server does not work on musl-based environments like Alpine.
+
 ##### Automatic Time Skipping
 
 Anytime a workflow result is waiting on, the time-skipping server automatically advances to the next event it can. To
@@ -1130,8 +1132,8 @@ included when using modern versions of .NET on a common platform. If you are usi
 explicitly set the platform to `x64` or `arm64` because `AnyCPU` will not choose the proper library.
 
 Currently we only support [RIDs](https://learn.microsoft.com/en-us/dotnet/core/rid-catalog) `linux-arm64`,
-`linux-x64`, `osx-arm64`, `osx-x64`, and `win-x64`. Any other platforms needed (e.g. `linux-musl-x64` on Alpine) will
-require a custom build.
+`linux-x64`, `linux-musl-x64`, `osx-arm64`, `osx-x64`, and `win-x64`. Any other platforms needed (e.g. `linux-musl-x64`
+on Alpine) will require a custom build.
 
 The native shared library on Windows does require a Visual C++ runtime. Some containers, such as Windows Nano Server, do
 not include this runtime. If not available, users may have to manually copy this runtime (usually just

src/Temporalio/Testing/WorkflowEnvironment.cs

@@ -85,6 +85,19 @@ public static async Task<WorkflowEnvironment> StartTimeSkippingAsync(
             WorkflowEnvironmentStartTimeSkippingOptions? options = null)
         {
             options ??= new();
+
+            // If they did not provide a binary to use, eagerly fail on musl since musl
+            // time-skipping is not supported at this time. We can only do this check in .NET 5+,
+            // otherwise we assume it is not musl for now since this is just a temporary situation.
+            // TODO(cretz): Remove when musl-support for time-skipping test server is present.
+#if NET5_0_OR_GREATER
+            if (System.Runtime.InteropServices.RuntimeInformation.Contains("-musl", StringComparison.OrdinalIgnoreCase))
+            {
+                throw new InvalidOperationException(
+                    "Time-skipping test server not currently supported in musl-based environments");
+            }
+#endif
+
             var runtime = options.Runtime ?? TemporalRuntime.Default;
             var server = await Bridge.EphemeralServer.StartTestServerAsync(
                 runtime.Runtime,