Add initial role for Dendrite as alternative Matrix server

roles/matrix-dendrite/tasks/self_check_federation_api.yml

@@ -0,0 +1,25 @@
+---
+- name: Check Matrix Federation API
+  uri:
+    url: "{{ matrix_dendrite_federation_api_url_endpoint_public }}"
+    follow_redirects: none
+    validate_certs: "{{ matrix_dendrite_self_check_validate_certificates }}"
+  register: result_matrix_dendrite_federation_api
+  ignore_errors: true
+  check_mode: no
+  when: matrix_dendrite_enabled|bool
+
+- name: Fail if Matrix Federation API not working
+  fail:
+    msg: "Failed checking Matrix Federation API is up at `{{ matrix_server_fqn_matrix }}` (checked endpoint: `{{ matrix_dendrite_federation_api_url_endpoint_public }}`). Is Dendrite running? Is port {{ matrix_federation_public_port }} open in your firewall? Full error: {{ result_matrix_dendrite_federation_api }}"
+  when: "matrix_dendrite_enabled|bool and matrix_dendrite_federation_enabled|bool and (result_matrix_dendrite_federation_api.failed or 'json' not in result_matrix_dendrite_federation_api)"
+
+- name: Fail if Matrix Federation API unexpectedly enabled
+  fail:
+    msg: "Matrix Federation API is up at `{{ matrix_server_fqn_matrix }}` (checked endpoint: `{{ matrix_dendrite_federation_api_url_endpoint_public }}`) despite being disabled."
+  when: "matrix_dendrite_enabled|bool and not matrix_dendrite_federation_enabled|bool and not result_matrix_dendrite_federation_api.failed"
+
+- name: Report working Matrix Federation API
+  debug:
+    msg: "The Matrix Federation API at `{{ matrix_server_fqn_matrix }}` (checked endpoint: `{{ matrix_dendrite_federation_api_url_endpoint_public }}`) is working"
+  when: "matrix_dendrite_enabled|bool and matrix_dendrite_federation_enabled|bool"