read rake secret from file

playbook.yml

@@ -221,11 +221,10 @@
       shell: '{{ bundle }} exec rake secret | tee /opt/greenlight/rake_secret'
       args:
         creates: /opt/greenlight/rake_secret
-      register: rake_secret
     - name: assert rake secret was created
       assert:
         that:
-          - rake_secret.stdout != ''
+          - lookup('file', '/opt/greenlight/rake_secret') != ''
     - name: obtain BBB API secret
       shell: "bbb-conf --secret | grep -oP 'Secret: \\K[[:alnum:]]+'"
       register: api_secret
@@ -242,7 +241,7 @@
         regexp: '^{{ item.key }}=.*$'
         replace: '{{ item.key }}={{ item.value }}'
       with_dict:
-        SECRET_KEY_BASE: "{{ rake_secret.stdout }}"
+        SECRET_KEY_BASE: "{{ lookup('file', '/opt/greenlight/rake_secret') }}"
         BIGBLUEBUTTON_ENDPOINT: 'https://{{ ansible_fqdn }}/bigbluebutton/'
         BIGBLUEBUTTON_SECRET: '{{ api_secret.stdout }}'
         SAFE_HOSTS: '{{ ansible_fqdn }}'