ci: Add github actions for CI & nightly tests

.github/actions/setup-nix/action.yml

@@ -0,0 +1,40 @@
+name: Setup Nix
+description: Install Nix with dev shell and optional KVM support
+
+inputs:
+  enable-kvm:
+    description: Enable KVM for NixOS VM tests
+    default: 'false'
+
+runs:
+  using: composite
+  steps:
+    - name: Enable KVM group permissions
+      if: inputs.enable-kvm == 'true'
+      shell: bash
+      run: |
+        echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules
+        sudo udevadm control --reload-rules
+        sudo udevadm trigger --name-match=kvm
+
+    - name: Install Nix
+      uses: cachix/install-nix-action@v31
+      with:
+        extra_nix_config: |
+          experimental-features = nix-command flakes
+          system-features = nixos-test benchmark big-parallel kvm
+
+    - name: Setup magic-nix-cache
+      uses: DeterminateSystems/magic-nix-cache-action@main
+
+    - name: Install direnv
+      shell: bash
+      run: |
+        nix profile install nixpkgs#direnv nixpkgs#nix-direnv
+        echo 'source $HOME/.nix-profile/share/nix-direnv/direnvrc' >> "$HOME/.direnvrc"
+
+    - name: Load dev shell environment
+      shell: bash
+      run: |
+        direnv allow .
+        direnv export json | jq -r 'to_entries[] | select(.value | contains("\n") | not) | "\(.key)=\(.value)"' >> "$GITHUB_ENV"

.github/workflows/ci.yml

@@ -0,0 +1,91 @@
+name: CI
+
+on:
+  push:
+    branches: [master, main]
+  pull_request:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "-D warnings"
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+
+      - name: Check formatting
+        run: cargo fmt --all -- --check
+
+      - name: Run clippy
+        run: cargo clippy --all-targets --all-features -- -D warnings
+
+      - name: Build all crates
+        run: cargo build --all-targets
+
+      - name: Run unit tests
+        run: cargo test --workspace --exclude portalbd-dst
+
+  dst-quick:
+    runs-on: ubuntu-latest
+    needs: [check]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+
+      - name: Run quick DST (100 iterations)
+        env:
+          RUSTFLAGS: "--cfg tokio_unstable"
+        run: cargo test -p portalbd-dst simulation
+
+  build:
+    runs-on: ubuntu-latest
+    needs: [check]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+
+      - name: Build portalbd
+        run: nix build
+
+  nixos-tests:
+    runs-on: ubuntu-latest
+    needs: [build]
+    strategy:
+      fail-fast: false
+      matrix:
+        test:
+          - basic
+          - crash-recovery
+          - snapshot-semantics
+          - resource-exhaustion
+          - pjdfs
+          - csi-node
+          - csi-k3s
+          - trace-mkfs
+          - trace-pgbench
+          - trace-minecraft
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+        with:
+          enable-kvm: 'true'
+
+      - name: Run ${{ matrix.test }} test
+        run: nix run -L .#test-${{ matrix.test }}

.github/workflows/nightly.yml

@@ -0,0 +1,43 @@
+name: Nightly DST
+
+on:
+  schedule:
+    # Run at 2 AM UTC every day
+    - cron: '0 2 * * *'
+  workflow_dispatch:
+    inputs:
+      seed:
+        description: 'Optional seed for reproducible DST run'
+        required: false
+        type: string
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  dst-nightly:
+    runs-on: ubuntu-latest
+    timeout-minutes: 120
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+
+      - name: Run nightly DST (long-running)
+        env:
+          RUSTFLAGS: "--cfg tokio_unstable"
+          DST_SEED: ${{ inputs.seed }}
+        run: |
+          echo "Starting nightly DST run at $(date)"
+          cargo test -p portalbd-dst simulation -- --ignored --nocapture
+          echo "Completed nightly DST run at $(date)"
+
+      - name: Upload failure artifacts
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: dst-failure-${{ github.run_id }}
+          path: target/dst-failures/
+          if-no-files-found: ignore
+          retention-days: 30