CI: Move the documentation check to a separate job

- Cache the used Ruby gems

.github/workflows/ci-yardoc.yml

@@ -0,0 +1,65 @@
+name: "CI - Documentation Check"
+
+on:
+  push:
+    paths:
+      # NOTE: GitHub Actions do not allow using YAML references, the same path
+      # list is used below for the pull request event. Keep both lists in sync!!
+
+      # this file as well
+      - .github/workflows/ci-yardoc.yml
+      # all Ruby files
+      - service/Gemfile*
+      - service/*.gemspec
+      - service/**.rb
+      # the D-Bus introspection files
+      - doc/dbus/**.xml
+
+  pull_request:
+    paths:
+      # NOTE: GitHub Actions do not allow using YAML references, the same path
+      # list is used above for the push event. Keep both lists in sync!!
+
+      # this file as well
+      - .github/workflows/ci-yardoc.yml
+      # all Ruby files
+      - service/Gemfile*
+      - service/*.gemspec
+      - service/**.rb
+      # the D-Bus introspection files
+      - doc/dbus/**.xml
+
+jobs:
+  ruby_doc:
+    runs-on: ubuntu-latest
+
+    container:
+      image: registry.opensuse.org/opensuse/tumbleweed:latest
+
+    steps:
+
+    - name: Git Checkout
+      uses: actions/checkout@v3
+
+    - name: Configure and refresh repositories
+      # disable unused repositories to have faster refresh
+      run: zypper modifyrepo -d repo-non-oss repo-openh264 repo-update && zypper ref
+
+    - name: Install Ruby development files and XML tooling
+      run: zypper --non-interactive install gcc gcc-c++ make openssl-devel augeas-devel xmlstarlet
+
+    - uses: ruby/setup-ruby@v1
+      with:
+        working-directory: ./service
+        # the current TW version
+        ruby-version: "3.2"
+        # runs 'bundle install' and caches installed gems automatically
+        bundler-cache: true
+
+    - name: Generate doc
+      working-directory: ./service
+      run: bundle exec yardoc --fail-on-warning
+
+    - name: Check that introspected API and its docs have not diverged
+      working-directory: ./doc
+      run: make check

.github/workflows/ci.yml

@@ -98,44 +98,6 @@ jobs:
         flag-name: backend
         parallel: true
 
-  ruby_doc:
-    runs-on: ubuntu-latest
-    env:
-      COVERAGE: 1
-
-    defaults:
-      run:
-        working-directory: ./service
-
-    strategy:
-      fail-fast: false
-      matrix:
-        distro: [ "tumbleweed" ]
-
-    container:
-      image: registry.opensuse.org/yast/head/containers_${{matrix.distro}}/yast-ruby
-
-    steps:
-
-    - name: Git Checkout
-      uses: actions/checkout@v3
-
-    - name: Configure and refresh repositories
-      # disable unused repositories to have faster refresh
-      run: zypper modifyrepo -d repo-non-oss repo-openh264 repo-update && ( zypper ref || zypper ref || zypper ref )
-
-    - name: Install Ruby development files and XML tooling
-      run: zypper --non-interactive install gcc gcc-c++ make openssl-devel ruby-devel npm augeas-devel xmlstarlet
-
-    - name: Install RubyGems dependencies
-      run: bundle config set --local with 'development' && bundle install
-
-    - name: Generate doc
-      run: bundle exec yardoc --fail-on-warning
-
-    - name: Check that introspected API and its docs have not diverged
-      run: make -C ../doc check
-
   rust_ci:
     runs-on: ubuntu-latest
     env: