Add a role to install 'ntfy' push-notification server.

This commit adds a 'matrix-ntfy' role that runs Ntfy server in Docker with
simple configuration, and plumbing to add the role to the playbook.

TODO: documentation, self-check, database persistence.

roles/matrix-ntfy/tasks/init.yml

@@ -0,0 +1,5 @@
+---
+
+- set_fact:
+    matrix_systemd_services_list: "{{ matrix_systemd_services_list + ['matrix-ntfy.service'] }}"
+  when: matrix_ntfy_enabled|bool

roles/matrix-ntfy/tasks/main.yml

@@ -0,0 +1,10 @@
+---
+
+- import_tasks: "{{ role_path }}/tasks/init.yml"
+  tags:
+    - always
+
+- import_tasks: "{{ role_path }}/tasks/setup.yml"
+  tags:
+    - setup-all
+    - setup-ntfy

roles/matrix-ntfy/tasks/setup.yml

@@ -0,0 +1,58 @@
+---
+#
+# Tasks related to setting up matrix-ntfy
+#
+
+- name: Ensure matrix-ntfy image is pulled
+  docker_image:
+    name: "{{ matrix_ntfy_docker_image }}"
+    source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
+    force_source: "{{ matrix_ntfy_docker_image_force_pull if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
+    force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_ntfy_docker_image_force_pull }}"
+  when: "matrix_ntfy_enabled|bool"
+  register: result
+  retries: "{{ matrix_container_retries_count }}"
+  delay: "{{ matrix_container_retries_delay }}"
+  until: result is not failed
+
+- name: Ensure matrix-ntfy.service installed
+  template:
+    src: "{{ role_path }}/templates/systemd/matrix-ntfy.service.j2"
+    dest: "{{ matrix_systemd_path }}/matrix-ntfy.service"
+    mode: 0644
+  register: matrix_ntfy_systemd_service_result
+  when: matrix_ntfy_enabled|bool
+
+- name: Ensure systemd reloaded after matrix-ntfy.service installation
+  service:
+    daemon_reload: true
+  when: "matrix_ntfy_enabled|bool and matrix_ntfy_systemd_service_result.changed"
+
+#
+# Tasks related to getting rid of matrix-ntfy (if it was previously enabled)
+#
+
+- name: Check existence of matrix-ntfy service
+  stat:
+    path: "{{ matrix_systemd_path }}/matrix-ntfy.service"
+  register: matrix_ntfy_service_stat
+
+- name: Ensure matrix-ntfy is stopped
+  service:
+    name: matrix-ntfy
+    state: stopped
+    enabled: false
+    daemon_reload: true
+  register: stopping_result
+  when: "not matrix_ntfy_enabled|bool and matrix_ntfy_service_stat.stat.exists"
+
+- name: Ensure matrix-ntfy.service doesn't exist
+  file:
+    path: "{{ matrix_systemd_path }}/matrix-ntfy.service"
+    state: absent
+  when: "not matrix_ntfy_enabled|bool and matrix_ntfy_service_stat.stat.exists"
+
+- name: Ensure systemd reloaded after matrix-ntfy.service removal
+  service:
+    daemon_reload: true
+  when: "not matrix_ntfy_enabled|bool and matrix_ntfy_service_stat.stat.exists"