r/blackbox-exporter: Rework to run as container

Instead of downloading the `blackbox_exporter` binary from GitHub and
copying it to the managed node, the _blackbox-exporter_ role now
installs _podman_ and configures a systemd container unit (Quadlet) to
run it in a container.  This simplifies the deployment considerably, and
will make updating easier (just run the playbook with `-e
blackbox_exporter_pull_image=true`).

roles/blackbox-exporter/tasks/deploy.yml

@@ -1,3 +1,26 @@
+- name: ensure blackbox container is present
+  podman_image:
+    name: '{{ blackbox_container_image_name }}'
+    tag: '{{ blackbox_container_image_tag }}'
+    state: present
+    pull: '{{ blackbox_exporter_pull_image|d(false)|bool }}'
+  notify:
+  - reload systemd
+  - restart blackbox-exporter
+  tags:
+  - container
+
+- name: ensure blackbox-exporter system container is configured
+  template:
+    src: blackbox-exporter.container.j2
+    dest: /etc/containers/systemd/blackbox-exporter.container
+    mode: u=rw,go=r
+    owner: root
+    group: root
+  notify:
+  - reload systemd
+  - restart blackbox-exporter
+
 - name: ensure /etc/prometheus directory exists
   file:
     path: /etc/prometheus
@@ -6,7 +29,7 @@
     group: root
     state: directory
 
-- name: ensure blackbox_exporter is configured
+- name: ensure blackbox-exporter is configured
   copy:
     dest: /etc/prometheus/blackbox.yml
     content: |
@@ -15,19 +38,22 @@
     owner: root
     group: root
   notify:
-  - reload blackbox_exporter
+  - reload blackbox-exporter
 
-- name: ensure blackbox_exporter starts at boot
+- name: flush handlers
+  meta: flush_handlers
+
+- name: ensure blackbox-exporter starts at boot
   service:
-    name: blackbox_exporter
+    name: blackbox-exporter
     enabled: true
   tags:
   - service
 - name: flush_handlers
   meta: flush_handlers
-- name: ensure blackbox_exporter is running
+- name: ensure blackbox-exporter is running
   service:
-    name: blackbox_exporter
+    name: blackbox-exporter
     state: started
   tags:
   - service