Move checks from unused validate_config.yml file elsewhere

roles/matrix-base/tasks/sanity_check.yml

@@ -39,9 +39,11 @@
     msg: |
       The `matrix_homeserver_generic_secret_key` variable must be defined and have a non-null and non-empty value.
 
-      If you're seeing this error on an existing homeserver installation, you can fix it easily this error by adding
+      If you're observing this error on a new installation, you should ensure that the `matrix_homeserver_generic_secret_key` is defined.
+
+      If you're observing this error on an existing homeserver installation, you can fix it easily and in a backward-compatible way by adding
       `{% raw %}matrix_homeserver_generic_secret_key: "{{ matrix_synapse_macaroon_secret_key }}"{% endraw %}`
-      to your vars.yml file. Using another secret for the new variable is also possible and shouldn't cause any trouble.
+      to your `vars.yml` file. Using another secret value for the new variable is also possible and shouldn't cause any trouble.
   when: "matrix_homeserver_generic_secret_key is none or matrix_homeserver_generic_secret_key == ''"
 
 - name: Fail if required variables are undefined
@@ -51,6 +53,8 @@
     - {'var': matrix_domain, 'value': "{{ matrix_domain|default('') }}"}
     - {'var': matrix_server_fqn_matrix, 'value': "{{ matrix_server_fqn_matrix|default('') }}"}
     - {'var': matrix_server_fqn_element, 'value': "{{ matrix_server_fqn_element|default('') }}"}
+    - {'var': matrix_homeserver_container_url, 'value': "{{ matrix_homeserver_container_url|default('') }}"}
+    - {'var': matrix_homeserver_container_federation_url, 'value': "{{ matrix_homeserver_container_federation_url|default('') }}"}
   when: "item.value is none or item.value == ''"
 
 - name: Fail if uppercase domain used

roles/matrix-base/tasks/validate_config.yml

@@ -1,10 +0,0 @@
----
-
-- name: Fail if required Matrix Base settings not defined
-  fail:
-    msg: >-
-      You need to define a required configuration setting (`{{ item }}`) for using this playbook.
-  when: "vars[item] == ''"
-  with_items:
-    - "matrix_homeserver_container_url"
-    - "matrix_homeserver_container_federation_url"