[ci] Add tests for non-native architectures

This change introduces a new job to the CI to test the SDK on non-native
architectures. Github CI ATM provides amd64 runners by default, so the
new job targets testing on arch64 for now.

The tests are run in containers running on the target platform(s). The
container definitions are supposed to exist in the directory
.github/containers/nox-cross-arch. A definition for an
arm64-ubuntu20.04-python3.11 container can be found there.

Since the tests take quite a while to run, given that they run on
emulations, this step runs only on the `merge_group` event.

Signed-off-by: Tiyash Basu <[email protected]>

.github/containers/nox-cross-arch/README.md

@@ -0,0 +1,21 @@
+# Cross-Arch Testing Containers
+
+This directory containers dockerfiles that can be used in the CI to test the
+python package in non-native machine architectures, e.g., `aarch64`.
+
+The dockerfiles here follow a naming scheme so that they can be easily used in
+build matrices in the CI, in `nox-cross-arch` job. The naming scheme is:
+
+```
+<arch>-<os>-python-<python-version>.Dockerfile
+```
+
+E.g.,
+
+```
+arm64-ubuntu-20.04-python-3.11.Dockerfile
+```
+
+If a dockerfile for your desired target architecture, OS, and python version
+does not exist here, please add one before proceeding to add your options to the
+test matrix.

.github/containers/nox-cross-arch/arm64-ubuntu-20.04-python-3.11.Dockerfile

@@ -0,0 +1,28 @@
+FROM docker.io/library/ubuntu:20.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install Python 3.11 and curl to install pip later
+RUN apt-get update -y && \
+    apt-get install --no-install-recommends -y \
+        software-properties-common && \
+    add-apt-repository ppa:deadsnakes/ppa && \
+    apt-get install --no-install-recommends -y \
+        ca-certificates \
+        curl \
+        git \
+        python3.11 \
+        python3.11-distutils && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Install pip
+RUN curl -sS https://bootstrap.pypa.io/get-pip.py | python3.11
+
+RUN update-alternatives --install \
+        /usr/local/bin/python python /usr/bin/python3.11 1 && \
+    python -m pip install --upgrade --no-cache-dir pip
+
+COPY entrypoint.bash /usr/bin/entrypoint.bash
+
+ENTRYPOINT ["/usr/bin/entrypoint.bash"]

.github/containers/nox-cross-arch/entrypoint.bash

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -e
+
+echo "System details:" $(uname -a)
+echo "Machine:" $(uname -m)
+
+pip install -e .[dev-noxfile]
+
+exec "$@"

.github/workflows/ci.yaml

@@ -79,6 +79,86 @@ jobs:
         run: nox -R -e "$NOX_SESSION"
         timeout-minutes: 10
 
+  nox-cross-arch:
+    name: Cross-arch tests with nox
+    if: github.event_name == 'merge_group'
+    strategy:
+      fail-fast: false
+      # Before adding new items to this matrix, make sure that a dockerfile
+      # exists for the combination of items in the matrix.
+      # Refer to .github/containers/nox-cross-arch/README.md to learn how to
+      # add and name new dockerfiles.
+      matrix:
+        arch:
+          - arm64
+        os:
+          - ubuntu-20.04
+        python:
+          - "3.11"
+        nox-session:
+          - "pytest_min"
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Fetch sources
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+        with:
+          platforms: linux/${{ matrix.arch }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      # This is a workaround to prevent the cache from growing indefinitely.
+      # https://docs.docker.com/build/ci/github-actions/cache/#local-cache
+      # https://github.com/docker/build-push-action/issues/252
+      # https://github.com/moby/buildkit/issues/1896
+      - name: Cache container layers
+        uses: actions/cache@v3
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-nox-${{ matrix.arch }}-${{ matrix.os }}-${{ matrix.python }}
+
+      - name: Build image
+        uses: docker/build-push-action@v4
+        with:
+          context: .github/containers/nox-cross-arch
+          file: .github/containers/nox-cross-arch/${{ matrix.arch }}-${{ matrix.os }}-python-${{ matrix.python }}.Dockerfile
+          platforms: linux/${{ matrix.arch }}
+          tags: localhost/nox-cross-arch:latest
+          push: false
+          load: true
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache-new,mode=max
+
+      # Refer to the workaround mentioned above
+      - name: Move cache
+        run: |
+          rm -rf /tmp/.buildx-cache
+          mv /tmp/.buildx-cache-new /tmp/.buildx-cache
+
+      # Cache nox downloads
+      - name: Cache nox downloads
+        uses: actions/cache@v3
+        with:
+          path: |
+            .nox/${{ matrix.nox-session }}
+          key: nox-${{ matrix.nox-session }}-${{ matrix.arch }}-${{ matrix.os }}-${{ matrix.python }}-${{ hashFiles('**/pyproject.toml') }}
+
+      - name: Run nox
+        run: |
+          docker run \
+            --rm \
+            -v $(pwd):/${{ github.workspace }} \
+            -w ${{ github.workspace }} \
+            --net=host \
+            --platform linux/${{ matrix.arch }} \
+            localhost/nox-cross-arch:latest \
+            nox -R -e ${{ matrix.nox-session }}
+        timeout-minutes: 30
+
   build:
     name: Build distribution packages
     runs-on: ubuntu-20.04

CONTRIBUTING.md

@@ -115,6 +115,10 @@ That said, if you want to test the actual website in **your fork**, you can
 always use `mike deploy --push --remote your-fork-remote`, and then access the
 GitHub pages produced for your fork.
 
+##  Cross-Arch Testing
+
+This project has built-in support for testing across multiple architectures. Currently, our CI conducts tests on `aarch64` machines using QEMU emulation. We also have the flexibility to expand this support to include additional architectures in the future. For more information, see [Cross-Arch Testing](.github/containers/nox-cross-arch/README.md).
+
 ## Releasing
 
 These are the steps to create a new release:

RELEASE_NOTES.md

@@ -18,6 +18,7 @@
 
 - A new class `Fuse` has been added to represent fuses. This class has a member variable `max_current` which represents the maximum current that can course through the fuse. If the current flowing through a fuse is greater than this limit, then the fuse will break the circuit.
 
+- The CI now runs cross-arch tests on `aarch64` architectures.
 
 ## Bug Fixes
 

docs/.github/containers/nox-cross-arch/README.md

@@ -0,0 +1 @@
+--8<-- ".github/containers/nox-cross-arch/README.md"