Add (native) Traefik support to matrix-client-hydrogen

Previously, it had to go through matrix-nginx-proxy.
It's exposed to Traefik directly via container labels now

Serving at a path other than `/` doesn't work well yet.

roles/custom/matrix-client-hydrogen/tasks/setup_install.yml

@@ -52,7 +52,7 @@
     group: "{{ matrix_user_groupname }}"
   with_items:
     - {src: "{{ role_path }}/templates/nginx.conf.j2", name: "nginx.conf"}
-  when: "item.src is not none"
+    - {src: "{{ role_path }}/templates/labels.j2", name: "labels"}
 
 - name: Ensure Hydrogen Docker image is built
   community.docker.docker_image:
@@ -65,6 +65,11 @@
       pull: true
   when: "matrix_client_hydrogen_container_image_self_build | bool"
 
+- name: Ensure Hydrogen container network is created
+  community.general.docker_network:
+    name: "{{ matrix_client_hydrogen_container_network }}"
+    driver: bridge
+
 - name: Ensure matrix-client-hydrogen.service installed
   ansible.builtin.template:
     src: "{{ role_path }}/templates/systemd/matrix-client-hydrogen.service.j2"

roles/custom/matrix-client-hydrogen/tasks/validate_config.yml

@@ -7,3 +7,34 @@
   when: "(vars[item] == '' or vars[item] is none) and matrix_client_hydrogen_container_image_self_build | bool"
   with_items:
     - "matrix_client_hydrogen_default_hs_url"
+
+- when: matrix_client_hydrogen_container_labels_traefik_enabled | bool
+  block:
+    - name: Fail if required matrix-client-hydrogen Traefik settings not defined
+      ansible.builtin.fail:
+        msg: >-
+          You need to define a required configuration setting (`{{ item }}`).
+      when: "vars[item] == ''"
+      with_items:
+        - matrix_client_hydrogen_container_labels_traefik_hostname
+        - matrix_client_hydrogen_container_labels_traefik_path_prefix
+
+    # We ensure it doesn't end with a slash, because we handle both (slash and no-slash).
+    # Knowing that `matrix_client_hydrogen_container_labels_traefik_path_prefix` does not end with a slash
+    # ensures we know how to set these routes up without having to do "does it end with a slash" checks elsewhere.
+    - name: Fail if matrix_client_hydrogen_container_labels_traefik_path_prefix ends with a slash
+      ansible.builtin.fail:
+        msg: >-
+          matrix_client_hydrogen_container_labels_traefik_path_prefix (`{{ matrix_client_hydrogen_container_labels_traefik_path_prefix }}`) must either be `/` or not end with a slash (e.g. `/hydrogen`).
+      when: "matrix_client_hydrogen_container_labels_traefik_path_prefix != '/' and matrix_client_hydrogen_container_labels_traefik_path_prefix[-1] == '/'"
+
+    # For example, we're getting errors like this:
+    # > main.js:51 Failed to load stylesheet from https://DOMAIN/assets/theme-element-light.5316e268.css:
+    # despite having set a prefix of `/hydrogen`.
+    # This is yet to be investigated and workaround around.
+    - name: Fail if matrix_client_hydrogen_container_labels_traefik_path_prefix is not /
+      ansible.builtin.fail:
+        msg: >-
+          matrix_client_hydrogen_container_labels_traefik_path_prefix can only be set to `/` right now.
+          Serving Hydrogen from another path doesn't work just yet.
+      when: "matrix_client_hydrogen_container_labels_traefik_path_prefix != '/'"