github: add buck2 ci build

Signed-off-by: Austin Seipp <[email protected]>

.github/actions/install-dotslash/action.yml

@@ -0,0 +1,26 @@
+name: Install DotSlash
+description: Install DotSlash on the current system
+inputs:
+  version:
+    description: "version of dotslash"
+    required: false
+    default: "0.4.1"
+runs:
+  using: "composite"
+  steps:
+    - name: Install DotSlash
+      shell: bash
+      run: |
+        if [[ "$RUNNER_OS" == "Windows" ]]; then
+          wget https://github.com/facebook/dotslash/releases/download/v0.4.1/dotslash-windows.v0.4.1.tar.gz
+          tar xf dotslash-windows.v0.4.1.tar.gz
+          exit 1
+        elif [[ "$RUNNER_OS" == "macOS" ]]; then
+          wget https://github.com/facebook/dotslash/releases/download/v0.4.1/dotslash-macos.v0.4.1.tar.gz
+          tar xf dotslash-macos.v0.4.1.tar.gz
+          exit 1
+        elif [[ "$RUNNER_OS" == "Linux" ]]; then
+          wget https://github.com/facebook/dotslash/releases/download/v0.4.1/dotslash-ubuntu-22.04.x86_64.v0.4.1.tar.gz
+          tar xf dotslash-ubuntu-22.04.x86_64.v0.4.1.tar.gz
+          mv dotslash /usr/local/bin/dotslash
+        fi

.github/workflows/build-buck2.yml

@@ -0,0 +1,34 @@
+name: buck2
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+permissions: read-all
+
+jobs:
+  nix:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+          - os: windows-latest
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 15 # NOTE (aseipp): keep in-sync with the build.yml timeout limit
+
+    name: build with buck2
+    steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - name: Install DotSlash
+        uses: ./.github/actions/install-dotslash
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@1482605bfc5719782e1267fd0c0cc350fe7646b8
+        with:
+          toolchain: 1.76
+      - name: buck2 build //...
+        run: |
+          dotslash --version
+          dotslash ./tools/bin/buck2 --version