Use sanitized github.ref

.gitea/workflows/build-and-push.yaml

@@ -25,6 +25,30 @@ jobs:
           # echo "MY_LOWER=$lower_value" >> $GITHUB_ENV
           # If you want to use it as an output of this step:
           echo "lowercase=$lower_value" >> $GITHUB_OUTPUT
+      - name: Convert ref to buildx safe value
+        id: docker_tag_from_ref
+        shell: bash
+        run: |
+          # Grab the raw ref
+          REF="${{ github.ref }}"
+
+          # Strip the "refs/*/" prefix (refs/heads/, refs/tags/…)
+          TAG=${REF#refs/*/}
+
+          # Replace characters that Docker tags disallow
+          #   * "/"  → "-"
+          #   * ":"  → "-"
+          #   * Any other non‑alphanumeric / . / _ / - → "-"
+          TAG=${TAG//\//-}
+          TAG=${TAG//:/-}
+          TAG=${TAG//[^a-zA-Z0-9._-]/-}
+
+          # (Optional) force lower‑case – Docker tags are case‑sensitive,
+          #   but many people prefer lower‑case
+          TAG=${TAG,,}
+
+          # Export to the action's output
+          echo "docker-tag=${TAG}" >> $GITHUB_OUTPUT
       # ------------------------------------------------------------------
       # 1. Checkout repository
       # ------------------------------------------------------------------
@@ -70,7 +94,7 @@ jobs:
           push: false
           tags: |
             ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.sha }}
-            ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.ref_name }}
+            ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ steps.docker_tag_from_ref.outputs.docker-tag }}
             ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:latest
           build-args: |
             # Add any build args here
@@ -89,7 +113,7 @@ jobs:
           push: true
           tags: |
             ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.sha }}
-            ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.ref_name }}
+            ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ steps.docker_tag_from_ref.outputs.docker-tag }}
             ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:latest
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache
@@ -108,5 +132,5 @@ jobs:
         run: |
           echo "Pushed image tags:"
           echo "- ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.sha }}"
-          echo "- ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ github.ref_name }}"
+          echo "- ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:${{ steps.docker_tag_from_ref.outputs.docker-tag }}"
           echo "- ${{ vars.REGISTRY_HOST }}/${{ steps.github_repository_to_lowercase.outputs.lowercase }}:latest"