[TT-16285] add s3 assets fetch step before dashboard image build in gateway (#431)

add s3 assets fetch step before dashboard image build in gateway

Author: jeffy-mathew

policy/templates/releng/.github/workflows/release.yml.d/tyk-dashboard-resolver.gotmpl

@@ -238,6 +238,26 @@
           echo "✅ Updated go.mod:"
           grep "github.com/TykTechnologies/tyk" go.mod
 
+      - name: Fetch pre-built UI assets from S3
+        env:
+          AWS_ACCESS_KEY_ID: {{`${{ secrets.AWS_BINDATA_ACCESS_KEY_ID }}`}}
+          AWS_SECRET_ACCESS_KEY: {{`${{ secrets.AWS_BINDATA_SECRET_ACCESS_KEY }}`}}
+          AWS_REGION: eu-central-1
+          AWS_SESSION_TOKEN: ""
+        run: |
+          # Read the vendored commit SHA
+          ASSETS_COMMIT=$(cat .assets_vendor | head -n 1 | tr -d '\n')
+
+          echo "Fetching UI assets for commit: ${ASSETS_COMMIT}"
+          aws s3 sync s3://tyk-dashboard-assets-ci/commits/${ASSETS_COMMIT}/ internal/uiassets/dist/
+
+          if [ ! -f internal/uiassets/dist/_index.html ]; then
+            echo "❌ Failed to fetch assets: _index.html not found"
+            exit 1
+          fi
+
+          echo "✓ Assets fetched successfully to internal/uiassets/dist/"
+
       - name: Configure AWS credentials
         uses: aws-actions/configure-aws-credentials@v4
         with: