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 +26,12 @@ 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
           - os: macos-intel
             out-file: libtemporal_sdk_bridge.dylib
             out-prefix: osx-x64
@@ -129,10 +136,12 @@ 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

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,