Add support to build with Cargo

Adds the ability to build both with Bazel and Cargo. Bazel will
still be the primary and Cargo will be the secondary. All
files required by Cargo will be generated from Bazel.

closes: #231

.github/workflows/main.yml

@@ -8,6 +8,49 @@ on:
     branches: [ main ]
 
 jobs:
+  cargo-tests:
+    # The type of runner that the job will run on.
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        # Which OS versions we will test on.
+        os_version: [ 20.04 ]
+    steps:
+    - uses: actions/checkout@v3.5.3
+      with:
+        fetch-depth: 0
+
+    - uses: docker/setup-buildx-action@v2
+    - uses: docker/build-push-action@v4
+      with:
+        context: .
+        file: ./deployment-examples/docker-compose/Dockerfile
+        build-args: |
+          OPT_LEVEL=fastbuild
+          OS_VERSION=${{ matrix.os_version }}
+        # The `builder` stage is pointless to be cached because any change to the
+        # PR invalidates it. So to save the limited cache space we skip it.
+        no-cache-filters: |
+          builder-final
+        target: builder-externals-built
+        load: true # This brings the build into `docker images` from buildx.
+        tags: allada/turbo-cache:test
+        cache-from: type=gha,scope=main
+        cache-to: type=gha,scope=main,mode=max
+
+    - name: Cargo.toml is up to date
+      run: |
+        docker run --rm -e CC=clang -v $PWD:/root/turbo-cache allada/turbo-cache:test python3 ./tools/build_cargo_manifest.py && \
+        git diff --exit-code || \
+        (echo "Cargo.toml is out of date. Please run: python ./tools/build_cargo_manifest.py" && exit 1)
+    - name: Compile & test with cargo
+      run: |
+        docker run --rm -e CC=clang -v $PWD:/root/turbo-cache allada/turbo-cache:test sh -c ' \
+          apt-get update && apt-get install cargo -y && \
+          cargo build --all && \
+          cargo test --all \
+        '
+
   unit-test:
     # The type of runner that the job will run on.
     runs-on: ubuntu-22.04

.gitignore

@@ -5,3 +5,4 @@ target/
 .config
 terraform.tfstate*
 .update_scheduler_ips.zip
+__pycache__