Set Ruby version for Dockerfile from .ruby-version

.github/workflows/rails-integration-tests.yml

@@ -20,6 +20,16 @@ jobs:
         run: |
           rails_versions=$(curl https://rubygems.org/api/v1/versions/rails.json | jq '[.[] | select(.number | test("beta") | not)] | group_by(.number[:1])[] | (.[0].number) | select(.[:1]|tonumber > 5)' | jq -s -c)
           echo "RAILS_VERSIONS=$rails_versions" >> $GITHUB_OUTPUT
+  set-ruby-version:
+    runs-on: ubuntu-latest
+    name: Set Rails versions
+    outputs:
+      RAILS_VERSIONS: ${{ steps.set-ruby-version.outputs.RUBY_VERSION }}
+    steps:
+     -  id: set-ruby-version
+        name: Set Ruby version
+        run: |
+          echo "RUBY_VERSION=$(cat .ruby-version)" >> $GITHUB_OUTPUT
   build-rails:
     strategy:
       fail-fast: false
@@ -28,7 +38,9 @@ jobs:
         rails: ${{ fromJSON(needs.set-matrix.outputs.RAILS_VERSIONS) }}
     runs-on: ubuntu-latest
     name: Build and cache Docker containers
-    needs: set-matrix
+    needs:
+      - set-matrix
+      - set-ruby-version
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -42,6 +54,7 @@ jobs:
           build-args: |
             RAILS_VERSION=${{ matrix.rails }}
             MAIL_NOTIFY_BRANCH=${{ github.ref }}
+            RUBY_VERSION=${{ needs.set-ruby-version.outputs.RUBY_VERSION }}
           push: false
           tags: mail-notify-integration-rails-${{ matrix.rails }}:latest
           outputs: type=docker, dest=/tmp/rails-${{ matrix.rails }}-image.tar
@@ -61,6 +74,7 @@ jobs:
     runs-on: ubuntu-latest
     needs:
       - set-matrix
+      - set-ruby-version
       - build-rails
     steps:
       - name: Download image
@@ -85,6 +99,7 @@ jobs:
     runs-on: ubuntu-latest
     needs:
       - set-matrix
+      - set-ruby-version
       - build-rails
     steps:
       - name: Download image