Add Dockerfile for arm64 compilation

Add a Dockerfile to compile for arm64 AoT on GitHub Actions (until they have a native arm64 runner).

.dockerignore

@@ -0,0 +1,26 @@
+**/.DS_Store
+**/.dockerignore
+**/.env
+**/.git
+**/.gitignore
+**/.project
+**/.settings
+**/.toolstarget
+**/.vs
+**/.vscode
+**/*.*proj.user
+**/*.dbmdl
+**/artifacts
+**/bin
+**/charts
+**/docker-compose*
+**/compose*
+**/Dockerfile*
+**/obj
+**/secrets.dev.yaml
+**/values.dev.yaml
+LICENSE
+README.md
+!.git/HEAD
+!.git/config
+!.git/refs/heads/

.github/workflows/build.yml

@@ -68,6 +68,11 @@ jobs:
         file: ./artifacts/coverage/coverage.cobertura.xml
         flags: ${{ matrix.os_name }}
 
+    - name: Build for arm64 with Docker
+      if: runner.os == 'Linux'
+      run: |
+        docker build --platform linux/arm64 --output . .
+
     - name: Publish artifacts
       uses: actions/upload-artifact@a8a3f3ad30e3422c9c7b888a15615d19a852ae32 # v3.1.3
       with:
@@ -77,7 +82,7 @@ jobs:
     - name: Create Lambda ZIP file
       if: runner.os == 'Linux'
       run: |
-        cd "./artifacts/publish/LondonTravel.Skill/release_linux-x64" || exit
+        cd "./artifacts/publish/LondonTravel.Skill/release_linux-arm64" || exit
         if [ -f "./bootstrap" ]
         then
           chmod +x ./bootstrap

Dockerfile

@@ -0,0 +1,15 @@
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:8.0@sha256:bb65e39b662be0265f780afae9cdbfcaa315ef63edb245ad9fb2aa1aabca0b6b AS build
+ARG TARGETARCH
+
+RUN dpkg --add-architecture arm64
+RUN apt update && apt install --yes clang gcc-aarch64-linux-gnu llvm zlib1g-dev zlib1g-dev:arm64
+
+WORKDIR /source
+
+COPY . .
+RUN --mount=type=cache,id=nuget,target=/root/.nuget/packages \
+    dotnet publish ./src/LondonTravel.Skill --runtime linux-arm64 --self-contained true /p:AssemblyName=bootstrap /p:PublishAot=true /p:PublishReadyToRun=true
+
+FROM scratch AS export
+ARG TARGETARCH
+COPY --from=build /source/artifacts/publish/LondonTravel.Skill/release_*/ ./artifacts/publish/LondonTravel.Skill/release_arm64

src/LondonTravel.Skill/aws-lambda-tools-defaults.json

@@ -3,7 +3,7 @@
   "region": "eu-west-1",
   "configuration": "Release",
   "framework": "net8.0",
-  "function-architecture": "x86_64",
+  "function-architecture": "arm64",
   "function-handler": "LondonTravel.Skill",
   "function-memory-size": 192,
   "function-runtime": "provided.al2023",