Fix error when publishing charmcraft.yaml only charm

Since charmcraft 2.5, the files: metadata.yaml, actions.yaml, and
config.yaml have been merged into charmcraft.yaml.
The publishing job fails because it expects the metadata.yaml to be
present.
This change checks for which file to use.
The keys looked up in metadata.yaml for this specific task have the same
schema in charmcraft.yaml

Change-Id: I94ea3b8230e5dbf7d2474410fba7acc5e0836a63

roles/charm-publish/tasks/publish.yaml

@@ -19,10 +19,28 @@
       include_role:
         name: ensure-docker
 
+    - name: Get metadata.yaml information
+      stat:
+        path: "{{ zuul.executor.work_root+'/'+zuul.project.src_dir+'/charms/'+charm_build_name+'/metadata.yaml'"
+      register: metadata_file
+
+    - name: Get charmcraft.yaml information
+      stat:
+        path: "zuul.executor.work_root+'/'+zuul.project.src_dir+'/charms/'+charm_build_name+'/charmcraft.yaml'"
+      register: charmcraft_file
+
+    - name: Register resource file
+      set_fact:
+        resource_file: "{{ metadata_file.stat.exists | ternary(metadata_file.stat.path, charmcraft_file.stat.path) }}"
+
+    - name: Which metadata file is used
+      debug:
+        msg: "{{ resource_file }}"
+
     - name: Upload oci-image to charmhub
       register: upload_oci_image_output
       vars:
-        metadata: "{{ lookup('file', zuul.executor.work_root+'/'+zuul.project.src_dir+'/charms/'+charm_build_name+'/metadata.yaml') | from_yaml }}"
+        metadata: "{{ lookup('file', resource_file) | from_yaml }}"
       args:
         executable: /bin/bash
       shell: |
@@ -52,8 +70,7 @@
       # TODO: The below command can error out with a message that says
       # upload with that digest already exists. This case need to be handled.
       # More details https://github.com/canonical/charmcraft/issues/826
-      command:
-        charmcraft upload -v --name {{ charm_build_name }} {{ charm_build_name }}.charm
+      command: charmcraft upload -v --name {{ charm_build_name }} {{ charm_build_name }}.charm
       retries: 3
       until: >
         ("Revision" in upload_charm_output.stdout)
@@ -64,8 +81,7 @@
 
     - name: Release charm
       register: release_charm_output
-      command:
-        charmcraft release {{ charm_build_name }} --revision {{ charm_revision }} --channel {{ publish_channel }} {{ resource_revision_flags | default("") }}
+      command: charmcraft release {{ charm_build_name }} --revision {{ charm_revision }} --channel {{ publish_channel }} {{ resource_revision_flags | default("") }}
       retries: 3
       until: >
         ("Revision" in release_charm_output.stdout)