r/v-m: Add role for Victoria Metrics

The *victoria-metrics* role deploys a single-server instance of the
Victoria Metrics time series database server.  It installs the selected
version by downloading the binary release from Github and copying it to
`/usr/local/sbin` on the managed node.  Scrape configuration is optional
and can be specified with the `scrape_configs` variable.

roles/victoria-metrics/tasks/install.yml

@@ -0,0 +1,61 @@
+- name: load installation variables
+  include_vars: install.yml
+
+- name: load architecture variables
+  include_vars: '{{ item }}'
+  with_first_found:
+  - '{{ ansible_architecture }}.yml'
+  - arch-defaults.yml
+
+- name: ensure victoria metrics release archive is available
+  delegate_to: localhost
+  become: false
+  get_url:
+    url: '{{ vm_tar_url }}'
+    checksum: 'sha256:{{ vm_cksm_url }}'
+    dest: '{{ playbook_dir }}/{{ vm_tar_name }}'
+  tags:
+  - download
+
+- name: ensure victoria metrics unpack dir exists locally
+  delegate_to: localhost
+  become: false
+  file:
+    path: '{{ vm_extract_dir }}'
+    mode: '0755'
+    state: directory
+  tags:
+  - unarchive
+
+- name: ensure victoria metrics archive is unpacked locally
+  delegate_to: localhost
+  become: false
+  unarchive:
+    src: '{{ playbook_dir }}/{{ vm_tar_name }}'
+    dest: '{{ vm_extract_dir }}'
+    remote_src: true
+    creates: '{{ vm_extract_dir }}/victoria-metrics-prod'
+  tags:
+  - unarchive
+
+- name: ensure victoria metrics is installed
+  copy:
+    src: '{{ vm_extract_dir }}/victoria-metrics-prod'
+    dest: /usr/local/sbin/victoria-metrics
+    mode: '0755'
+  diff: false
+  notify:
+  - restart victoria-metrics
+
+- name: ensure victoria metrics systemd unit is installed
+  file:
+    src: victoria-metrics.service
+    dest: /etc/systemd/system/victoria-metrics.service
+    mode: '0644'
+  notify:
+  - reload systemd
+  - restart victoria-metrics
+  tags:
+  - service
+  - systemd
+