Move roles/matrix* to roles/custom/matrix*

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.

roles/custom/matrix-prometheus/tasks/init.yml

@@ -0,0 +1,5 @@
+---
+
+- ansible.builtin.set_fact:
+    matrix_systemd_services_list: "{{ matrix_systemd_services_list + ['matrix-prometheus.service'] }}"
+  when: matrix_prometheus_enabled | bool

roles/custom/matrix-prometheus/tasks/main.yml

@@ -0,0 +1,23 @@
+---
+
+- ansible.builtin.import_tasks: "{{ role_path }}/tasks/init.yml"
+  tags:
+    - always
+
+- ansible.builtin.import_tasks: "{{ role_path }}/tasks/validate_config.yml"
+  when: "run_setup | bool and matrix_prometheus_enabled | bool"
+  tags:
+    - setup-all
+    - setup-prometheus
+
+- ansible.builtin.import_tasks: "{{ role_path }}/tasks/setup_install.yml"
+  when: "run_setup | bool and matrix_prometheus_enabled | bool"
+  tags:
+    - setup-all
+    - setup-prometheus
+
+- ansible.builtin.import_tasks: "{{ role_path }}/tasks/setup_uninstall.yml"
+  when: "run_setup | bool and not matrix_prometheus_enabled | bool"
+  tags:
+    - setup-all
+    - setup-prometheus

roles/custom/matrix-prometheus/tasks/setup_install.yml

@@ -0,0 +1,58 @@
+---
+
+- name: Ensure matrix-prometheus image is pulled
+  community.docker.docker_image:
+    name: "{{ matrix_prometheus_docker_image }}"
+    source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
+    force_source: "{{ matrix_prometheus_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_prometheus_docker_image_force_pull }}"
+  register: result
+  retries: "{{ matrix_container_retries_count }}"
+  delay: "{{ matrix_container_retries_delay }}"
+  until: result is not failed
+
+- name: Ensure Prometheus paths exists
+  ansible.builtin.file:
+    path: "{{ item }}"
+    state: directory
+    mode: 0750
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+  with_items:
+    - "{{ matrix_prometheus_base_path }}"
+    - "{{ matrix_prometheus_config_path }}"
+    - "{{ matrix_prometheus_data_path }}"
+
+- name: Download synapse-v2.rules
+  ansible.builtin.get_url:
+    url: "{{ matrix_prometheus_scraper_synapse_rules_download_url }}"
+    dest: "{{ matrix_prometheus_config_path }}/synapse-v2.rules"
+    force: true
+    mode: 0440
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+  when: "matrix_prometheus_scraper_synapse_rules_enabled | bool"
+  register: result
+  retries: "{{ matrix_geturl_retries_count }}"
+  delay: "{{ matrix_geturl_retries_delay }}"
+  until: result is not failed
+
+- name: Ensure prometheus.yml installed
+  ansible.builtin.copy:
+    content: "{{ matrix_prometheus_configuration | to_nice_yaml(indent=2, width=999999) }}"
+    dest: "{{ matrix_prometheus_config_path }}/prometheus.yml"
+    mode: 0644
+    owner: "{{ matrix_user_username }}"
+    group: "{{ matrix_user_groupname }}"
+
+- name: Ensure matrix-prometheus.service installed
+  ansible.builtin.template:
+    src: "{{ role_path }}/templates/systemd/matrix-prometheus.service.j2"
+    dest: "{{ matrix_systemd_path }}/matrix-prometheus.service"
+    mode: 0644
+  register: matrix_prometheus_systemd_service_result
+
+- name: Ensure systemd reloaded after matrix-prometheus.service installation
+  ansible.builtin.service:
+    daemon_reload: true
+  when: "matrix_prometheus_systemd_service_result.changed | bool"

roles/custom/matrix-prometheus/tasks/setup_uninstall.yml

@@ -0,0 +1,26 @@
+---
+
+- name: Check existence of matrix-prometheus service
+  ansible.builtin.stat:
+    path: "{{ matrix_systemd_path }}/matrix-prometheus.service"
+  register: matrix_prometheus_service_stat
+
+- name: Ensure matrix-prometheus is stopped
+  ansible.builtin.service:
+    name: matrix-prometheus
+    state: stopped
+    enabled: false
+    daemon_reload: true
+  register: stopping_result
+  when: "matrix_prometheus_service_stat.stat.exists | bool"
+
+- name: Ensure matrix-prometheus.service doesn't exist
+  ansible.builtin.file:
+    path: "{{ matrix_systemd_path }}/matrix-prometheus.service"
+    state: absent
+  when: "matrix_prometheus_service_stat.stat.exists | bool"
+
+- name: Ensure systemd reloaded after matrix-prometheus.service removal
+  ansible.builtin.service:
+    daemon_reload: true
+  when: "matrix_prometheus_service_stat.stat.exists | bool"

roles/custom/matrix-prometheus/tasks/validate_config.yml

@@ -0,0 +1,7 @@
+---
+
+- name: Fail if Synapse metrics or Prometheus Node Exporter not enabled
+  ansible.builtin.fail:
+    msg: >
+      You need to enable `matrix_prometheus_scraper_synapse_enabled` and/or `matrix_prometheus_scraper_node_enabled` for Prometheus grab metrics.
+  when: "not matrix_prometheus_scraper_synapse_enabled and not matrix_prometheus_scraper_node_enabled"