Gitea Actions: Automatically increase image tag by one

.gitea/workflows/build.yaml

@@ -0,0 +1,35 @@
+name: Build & Publish to GHCR
+
+on:
+  push:
+    branches:
+      - main
+
+env:
+  IMAGE_NAME: app-notifications-backend-api
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Log in to GHCR
+        run: echo "${{ secrets.GHCR_TOKEN }}" | docker login ghcr.io -u ${{ secrets.GHCR_USERNAME }} --password-stdin
+
+      - name: Get Latest Tag
+        id: get_tag
+        run: |
+          BASE64_TOKEN=$(echo "${{ secrets.GHCR_TOKEN }}" | base64)
+          LATEST_TAG=$(curl -s -H "Authorization: Bearer $BASE64_TOKEN" \
+            https://ghcr.io/v2/gansejunge/${{ env.IMAGE_NAME }}/tags/list \
+            | jq -r '.tags | map(select(test("^[0-9]+$"))) | map(tonumber) | max // 0')
+          NEXT_TAG=$((LATEST_TAG + 1))
+          echo "latest=$LATEST_TAG" >> $GITHUB_OUTPUT
+          echo "next=$NEXT_TAG" >> $GITHUB_OUTPUT
+
+      - name: Build and Push Docker Image
+        run: |
+          docker build -t ghcr.io/gansejunge/${{ env.IMAGE_NAME }}:${{ steps.get_tag.outputs.next }} .
+          docker push ghcr.io/gansejunge/${{ env.IMAGE_NAME }}:${{ steps.get_tag.outputs.next }}