CI: Introduce "Format & Lint" job

There is no need to build and run buildifier for each module and for every
GHC version in order to keep the code base in shape.

Tag the buildifier tests with `manual` and only run the buildifier for the
top-level repository (which formats / lints all files of the git repo).

.github/workflows/workflow.yaml

@@ -10,8 +10,41 @@ env:
   cache-version: 0
 
 jobs:
+  lint:
+    name: Format & Lint
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}-lint
+      cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Configure
+        env:
+          BUILDBUDDY_API_KEY: ${{ secrets.BUILDBUDDY_API_KEY }}
+        run: |
+          # Avoid failures of the form `deadline exceeded after 14999958197ns DEADLINE_EXCEEDED`.
+          # See https://github.com/tweag/rules_haskell/issues/1498 and https://github.com/tweag/rules_haskell/pull/1692.
+          [[ ${{ runner.os }} == Linux ]] && sudo sysctl -w net.ipv4.tcp_keepalive_time=60
+          if [ -z "$BUILDBUDDY_API_KEY" ]; then
+              cache_setting='--noremote_upload_local_results'
+          else
+              cache_setting="--remote_header=x-buildbuddy-api-key=$BUILDBUDDY_API_KEY"
+          fi
+          cat >.bazelrc.local <<EOF
+          common --config=ci
+          build $cache_setting
+          EOF
+          cat >~/.netrc <<EOF
+          machine api.github.com
+                  password ${{ secrets.GITHUB_TOKEN }}
+          EOF
+      - run: |
+          bazelisk test buildifier:buildifier_test
+
   test-nixpkgs:
     name: Build & Test - Nixpkgs
+    needs:
+      - lint
     concurrency:
       group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.os }}-${{ matrix.module }}-${{ matrix.bzlmod }}-${{ matrix.ghc }}-nixpkgs
       cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
@@ -115,6 +148,8 @@ jobs:
 
   test-bindist:
     name: Build & Test - bindist
+    needs:
+      - lint
     concurrency:
       group: ${{ github.workflow }}-${{ github.ref }}-${{ matrix.os }}-${{ matrix.module }}-${{ matrix.bzlmod }}-${{ matrix.ghc }}-bindist
       cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}

buildifier/BUILD.bazel

@@ -45,6 +45,7 @@ buildifier_test(
     mode = "diff",
     tags = [
         "dont_test_on_windows",
+        "manual",
     ],
 )
 

rules_haskell_nix/BUILD.bazel

@@ -17,6 +17,7 @@ buildifier_test(
     buildifier = "@buildifier//:buildifier",
     tags = [
         "dont_test_on_windows",
+        "manual",
     ],
     verbose = True,
 )

rules_haskell_tests/buildifier/BUILD.bazel

@@ -30,6 +30,7 @@ buildifier_test(
     mode = "diff",
     tags = [
         "dont_test_on_windows",
+        "manual",
     ],
 )