feature/build (#1)

Co-authored-by: Tobias Klemp <tobias.klemp@v-office.com>
Reviewed-on: #1

.gitea/actions/buildDockerImage.yml

@@ -0,0 +1,35 @@
+name: Build docker image
+inputs:
+  tag:
+    description: 'Docker image tag'
+    required: true
+
+outputs:
+  image_url:
+    description: 'Full image URL that was built'
+    value: ${{ steps.build.outputs.image_url }}
+
+jobs:
+  build_docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Build
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ vars.INSTANCE_URL }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.REGISTRY_ACCESS_TOKEN }}
+
+      - name: Build and push image
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          tags: ${{ vars.INSTANCE_URL }}/tech-reborn/phoenix:${{ inputs.tag }}
+
+      - name: Set output
+        shell: bash
+        run: |
+          echo "image_url=${{ vars.INSTANCE_URL }}/tech-reborn/phoenix:${{ inputs.tag }}" >> $GITHUB_OUTPUT