ci: Auto-determine checks to run

This will allow us to support multiple platforms easily.

.github/workflows/build.yaml

@@ -36,44 +36,4 @@ jobs:
           name: fossar
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
 
-      - name: Set job parameters
-        id: params
-        run: |
-          branch=${{ matrix.php.branch }}
-          major=${branch%%.*}
-          minor=${branch#*.}
-          attr=php$major$minor
-          echo "::set-output name=major::$major"
-          echo "::set-output name=attr::$attr"
-
-      - name: Build PHP
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-php
-
-      - name: Build Imagick extension
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-imagick
-
-      - name: Build Redis extension
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-redis
-
-      - name: Build Redis 3 extension
-        if: ${{ steps.params.outputs.major < 8 }}
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-redis3
-
-      - name: Build MySQL extension
-        if: ${{ steps.params.outputs.major < 7 }}
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-mysql
-
-      - name: Build Xdebug extension
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-xdebug
-
-      - name: Build Tidy extension
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-tidy
-
-      - name: Check that composer PHAR works
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-composer-phar
-
-      - name: Validate php.extensions.mysqli default unix socket path
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-mysqli-socket-path
-
-      - name: Validate php.extensions.pdo_mysql default unix socket path
-        run: nix-build -A outputs.checks.x86_64-linux.${{ steps.params.outputs.attr }}-pdo_mysql-socket-path
+      - run: nix-shell run-flake-checks.nix --argstr branch "${{ matrix.php.branch }}"

flake.nix

@@ -66,7 +66,8 @@
                             }:
 
                             drv // {
-                              description = "PHP ${phpVersion} – ${description}";
+                              inherit description;
+                              phpBranch = phpVersion;
                             }
                           )
                           supportedChecks;

run-flake-checks.nix

@@ -0,0 +1,67 @@
+# Runs Nix flake checks individually with group markers for GitHub Actions.
+# Invoke with `nix-shell run-flake-checks.nix --argstr branch "8.1"`
+{
+  # PHP attribute to run checks for. `null` for all checks.
+  branch ? null,
+}:
+
+let
+  self = import ./.;
+
+  pkgs = self.inputs.nixpkgs.legacyPackages.${builtins.currentSystem};
+  inherit (self.inputs.nixpkgs) lib;
+
+  checks = self.outputs.checks.${builtins.currentSystem};
+
+  phpName =
+    assert lib.assertMsg (builtins.match "[0-9]+.[0-9]+" branch != null) "Branch name “${builtins.toString branch}” does not match a version number.";
+
+    "php${lib.versions.major branch}${lib.versions.minor branch}";
+
+  relevantChecks =
+    if branch == null
+    then checks
+    else lib.filterAttrs (key: value: lib.hasPrefix "${phpName}-" key) checks;
+in
+
+assert lib.assertMsg (relevantChecks != { }) "No checks found for branch “${builtins.toString branch}”.";
+
+pkgs.stdenv.mkDerivation {
+  name = "run-flake-checks";
+
+  buildCommand = ''
+    echo 'Please run `nix-shell run-flake-checks.nix`, `nix-build` cannot be used.' > /dev/stderr
+    exit 1
+  '';
+
+  shellHook =
+    ''
+      set -o errexit
+    ''
+    + builtins.concatStringsSep
+      "\n"
+      (
+        lib.mapAttrsToList
+          (
+            name:
+            value:
+
+            let
+              description =
+                lib.optionalString (branch == null) "PHP ${value.phpBranch} – "
+                + value.description;
+            in
+            ''
+              echo "::group::${description}"
+              echo Run nix-build -A outputs.checks.${builtins.currentSystem}.${name}
+              nix-build --no-out-link -A outputs.checks.${builtins.currentSystem}.${name}
+              echo "::endgroup::"
+            ''
+          )
+          relevantChecks
+      )
+    + ''
+      exit 0
+    ''
+    ;
+}