propagate support for 'latest' version specifier from ansible-prometheus

README.md

@@ -24,7 +24,7 @@ All variables which can be overridden are stored in [defaults/main.yml](defaults
 
 | Name           | Default Value | Description                        |
 | -------------- | ------------- | -----------------------------------|
-| `alertmanager_version` | 0.16.1 | Alertmanager package version |
+| `alertmanager_version` | 0.16.1 | Alertmanager package version. Also accepts `latest` as parameter. |
 | `alertmanager_listen_address` | '0.0.0.0:9093' | Address on which alertmanager will be listening |
 | `alertmanager_external_url` | 'http://localhost:9093/' | External address on which alertmanager is available. Useful when behind reverse proxy. Ex. example.org/alertmanager |
 | `alertmanager_config_dir` | /etc/alertmanager | Path to directory with alertmanager configuration |

tasks/install.yml

@@ -27,26 +27,34 @@
 
 - name: download alertmanager binary to local folder
   become: false
-  unarchive:
-    src: "https://github.com/prometheus/alertmanager/releases/download/v{{ alertmanager_version }}/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch_map[ansible_architecture] | default(ansible_architecture) }}.tar.gz"
-    dest: "/tmp"
-    remote_src: true
-    creates: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch_map[ansible_architecture] | default(ansible_architecture) }}/alertmanager"
-  register: _download_binary
-  until: _download_binary is succeeded
+  get_url:
+    url: "https://github.com/prometheus/alertmanager/releases/download/v{{ alertmanager_version }}/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch }}.tar.gz"
+    dest: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch }}.tar.gz"
+    checksum: "sha256:{{ alertmanager_checksum }}"
+  register: _download_archive
+  until: _download_archive is succeeded
   retries: 5
   delay: 2
-  # run_once: true
+  # run_once: true # <-- this can't be set due to multi-arch support
+  delegate_to: localhost
+  check_mode: false
+
+- name: unpack alertmanager binaries
+  become: false
+  unarchive:
+    src: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch }}.tar.gz"
+    dest: "/tmp"
+    creates: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch }}/alertmanager"
   delegate_to: localhost
   check_mode: false
 
 - name: propagate alertmanager and amtool binaries
   copy:
-    src: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch_map[ansible_architecture] | default(ansible_architecture) }}/{{ item }}"
+    src: "/tmp/alertmanager-{{ alertmanager_version }}.linux-{{ go_arch }}/{{ item }}"
     dest: "/usr/local/bin/{{ item }}"
     mode: 0755
-    owner: alertmanager
-    group: alertmanager
+    owner: root
+    group: root
   with_items:
     - alertmanager
     - amtool
@@ -76,12 +84,3 @@
   when:
     - ansible_version.full is version_compare('2.4', '>=')
     - ansible_selinux.status == "enabled"
-
-- name: remove alertmanager binaries from old location
-  file:
-    path: "{{ item }}"
-    state: absent
-  with_items:
-    - /opt/alertmanager/alertmanager
-    - /opt/alertmanager/amtool
-    - /opt/alertmanager

tasks/preflight.yml

@@ -1,4 +1,49 @@
 ---
+- name: Assert usage of systemd as an init system
+  assert:
+    that: ansible_service_mgr == 'systemd'
+    msg: "This module only works with systemd"
+
+- name: Get systemd version
+  command: systemctl --version
+  changed_when: false
+  check_mode: false
+  register: __systemd_version
+  tags:
+    - skip_ansible_lint
+
+- name: Set systemd version fact
+  set_fact:
+    alertmanager_systemd_version: "{{ __systemd_version.stdout_lines[0].split(' ')[-1] }}"
+
+- block:
+    - name: Get latest release
+      uri:
+        url: "https://api.github.com/repos/prometheus/alertmanager/releases/latest"
+        method: GET
+        return_content: true
+        status_code: 200
+        body_format: json
+        validate_certs: false
+        user: "{{ lookup('env', 'GH_USER') | default(omit) }}"
+        password: "{{ lookup('env', 'GH_TOKEN') | default(omit) }}"
+      no_log: true
+      register: _latest_release
+      until: _latest_release.status == 200
+      retries: 5
+
+    - name: "Set prometheus version to {{ _latest_release.json.tag_name[1:] }}"
+      set_fact:
+        alertmanager_version: "{{ _latest_release.json.tag_name[1:] }}"
+  when: alertmanager_version == "latest"
+
+- name: "Get checksum for {{ go_arch }} architecture"
+  set_fact:
+    alertmanager_checksum: "{{ item.split(' ')[0] }}"
+  with_items:
+    - "{{ lookup('url', 'https://github.com/prometheus/alertmanager/releases/download/v' + alertmanager_version + '/sha256sums.txt', wantlist=True) | list }}"
+  when: "('linux-' + go_arch + '.tar.gz') in item"
+
 - name: Backward compatibility of variable [part 1]
   set_fact:
     alertmanager_config_flags_extra: "{{ alertmanager_cli_flags }}"

vars/main.yml

@@ -5,3 +5,5 @@ go_arch_map:
   aarch64: 'arm64'
   armv7l: 'armv7'
   armv6l: 'armv6'
+
+go_arch: "{{ go_arch_map[ansible_architecture] | default(ansible_architecture) }}"