ci: login to OpenStack provider

.github/actions/login_openstack/action.yml

@@ -0,0 +1,16 @@
+name: OpenStack login
+description: "Login to OpenStack"
+inputs:
+  clouds_yaml:
+    description: "Credentials authorized to create Constellation on OpenStack."
+    required: true
+runs:
+  using: "composite"
+  steps:
+   - name: Login to OpenStack
+     env:
+       CLOUDS_YAML: ${{ inputs.clouds_yaml }}
+     shell: bash
+     run: |
+        mkdir -p ~/.config/openstack
+        echo "${CLOUDS_YAML}" > ~/.config/openstack/clouds.yaml

.github/workflows/build-os-image.yml

@@ -162,6 +162,11 @@ jobs:
         with:
           service_account: "image-uploader@constellation-images.iam.gserviceaccount.com"
 
+      - name: Login to OpenStack
+        uses: ./.github/actions/login_openstack
+        with:
+          clouds_yaml: ${{ secrets.STACKIT_IMAGE_UPLOAD_CLOUDS_YAML }}
+
       - name: Build and upload
         id: build
         shell: bash