Replace cronjobs with systemd timers

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/756

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/737

I feel like timers are somewhat more complicated and dirty (compared to
cronjobs), but they come with these benefits:

- log output goes to journald
- on newer systemd distros, you can see when the timer fired, when it
will fire, etc.
- we don't need to rely on cron (reducing our dependencies to just
systemd + Docker)

Cronjobs work well, but it's one more dependency that needs to be
installed. We were even asking people to install it manually
(in `docs/prerequisites.md`), which could have gone unnoticed.

Once in a while someone says "my SSL certificates didn't renew"
and it's likely because they forgot to install a cron daemon.

Switching to systemd timers means that installation is simpler
and more unified.

roles/matrix-nginx-proxy/tasks/init.yml

@@ -1,3 +1,8 @@
 - set_fact:
     matrix_systemd_services_list: "{{ matrix_systemd_services_list + ['matrix-nginx-proxy.service'] }}"
   when: matrix_nginx_proxy_enabled|bool
+
+- set_fact:
+    matrix_systemd_services_list: "{{ matrix_systemd_services_list + [item.name] }}"
+  when: "item.applicable|bool and item.enableable|bool"
+  with_items: "{{ matrix_ssl_renewal_systemd_units_list }}"

roles/matrix-nginx-proxy/tasks/ssl/setup_ssl_lets_encrypt.yml

@@ -10,53 +10,56 @@
     - "{{ matrix_local_bin_path }}/matrix-ssl-certificates-renew"
     - "{{ matrix_cron_path }}/matrix-ssl-certificate-renewal"
     - "{{ matrix_cron_path }}/matrix-nginx-proxy-periodic-restarter"
+    - "/etc/cron.d/matrix-ssl-lets-encrypt"
+    - "{{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew"
 
 #
 # Tasks related to setting up Let's Encrypt's management of certificates
 #
 
-- name: Ensure certbot Docker image is pulled
-  docker_image:
-    name: "{{ matrix_ssl_lets_encrypt_certbot_docker_image }}"
-    source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
-    force_source: "{{ matrix_ssl_lets_encrypt_certbot_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_ssl_lets_encrypt_certbot_docker_image_force_pull }}"
-  when: "matrix_ssl_retrieval_method == 'lets-encrypt'"
+- block:
+    - name: Ensure certbot Docker image is pulled
+      docker_image:
+        name: "{{ matrix_ssl_lets_encrypt_certbot_docker_image }}"
+        source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
+        force_source: "{{ matrix_ssl_lets_encrypt_certbot_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_ssl_lets_encrypt_certbot_docker_image_force_pull }}"
 
-- name: Obtain Let's Encrypt certificates
-  include_tasks: "{{ role_path }}/tasks/ssl/setup_ssl_lets_encrypt_obtain_for_domain.yml"
-  with_items: "{{ matrix_ssl_domains_to_obtain_certificates_for }}"
-  loop_control:
-    loop_var: domain_name
-  when: "matrix_ssl_retrieval_method == 'lets-encrypt'"
+    - name: Obtain Let's Encrypt certificates
+      include_tasks: "{{ role_path }}/tasks/ssl/setup_ssl_lets_encrypt_obtain_for_domain.yml"
+      with_items: "{{ matrix_ssl_domains_to_obtain_certificates_for }}"
+      loop_control:
+        loop_var: domain_name
 
-- name: Ensure Let's Encrypt SSL renewal script installed
-  template:
-    src: "{{ role_path }}/templates/usr-local-bin/matrix-ssl-lets-encrypt-certificates-renew.j2"
-    dest: "{{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew"
-    mode: 0750
-  when: "matrix_ssl_retrieval_method == 'lets-encrypt'"
+    - name: Ensure Let's Encrypt SSL renewal script installed
+      template:
+        src: "{{ role_path }}/templates/usr-local-bin/matrix-ssl-lets-encrypt-certificates-renew.j2"
+        dest: "{{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew"
+        mode: 0750
 
-- name: Ensure periodic SSL renewal cronjob configured
-  template:
-    src: "{{ role_path }}/templates/cron.d/matrix-ssl-lets-encrypt.j2"
-    dest: /etc/cron.d/matrix-ssl-lets-encrypt
-    mode: 0644
+    - name: Ensure SSL renewal systemd units installed
+      template:
+        src: "{{ role_path }}/templates/systemd/{{ item.name }}.j2"
+        dest: "{{ matrix_systemd_path }}/{{ item.name }}"
+        mode: 0644
+      when: "item.applicable|bool"
+      with_items: "{{ matrix_ssl_renewal_systemd_units_list }}"
   when: "matrix_ssl_retrieval_method == 'lets-encrypt'"
 
-
 #
 # Tasks related to getting rid of Let's Encrypt's management of certificates
 #
 
-- name: Ensure matrix-ssl-lets-encrypt-renew cronjob removed
-  file:
-    path: /etc/cron.d/matrix-ssl-lets-encrypt
-    state: absent
-  when: "matrix_ssl_retrieval_method != 'lets-encrypt'"
+- block:
+    - name: Ensure matrix-ssl-lets-encrypt-renew cronjob removed
+      file:
+        path: "{{ matrix_systemd_path }}/{{ item.name }}"
+        state: absent
+      when: "{{ not item.applicable }}"
+      with_items: "{{ matrix_ssl_renewal_systemd_units_list }}"
 
-- name: Ensure Let's Encrypt SSL renewal script removed
-  file:
-    path: "{{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew"
-    state: absent
+    - name: Ensure Let's Encrypt SSL renewal script removed
+      file:
+        path: "{{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew"
+        state: absent
   when: "matrix_ssl_retrieval_method != 'lets-encrypt'"