add promtail role

roles/promtail/defaults/main.yaml

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+---
+promtail_go_arch_map:
+  i386: '386'
+  x86_64: 'amd64'
+
+promtail_go_arch: "{{ promtail_go_arch_map[ansible_architecture] | default('amd64') }}"
+
+promtail_service_name: promtail.service
+promtail_service_enabled: true
+promtail_service_state: started
+
+promtail_version_regex: ^promtail, version ([\d.]+)
+
+promtail_github_project_url: https://github.com/grafana/loki
+promtail_release_file: "promtail-{{ ansible_system | lower }}-{{ promtail_go_arch }}.zip"
+promtail_release_url: "{{ promtail_github_project_url }}/releases/download/v{{ promtail_version }}/{{ promtail_release_file }}"
+promtail_checksum_url: "{{ promtail_github_project_url }}/releases/download/v{{ promtail_version }}/SHA256SUMS"
+promtail_download_path: "/tmp/{{ promtail_release_file }}"
+promtail_unarchive_dest_path: /tmp
+promtail_extracted_path: "{{ promtail_download_path | replace('.zip', '') }}"
+
+promtail_user: promtail
+promtail_user_state: present
+promtail_user_shell: /usr/sbin/nologin
+
+promtail_group: promtail
+promtail_groups: adm
+promtail_group_state: "{{ promtail_user_state | default('present') }}"
+
+promtail_config_path: /etc/promtail.yaml
+
+promtail_var_path: /var/lib/promtail
+promtail_var_owner: "{{ promtail_user }}"
+promtail_var_group: "{{ promtail_group }}"
+promtail_var_mode: "0755"
+
+promtail_bin_path: /usr/local/bin
+
+promtail_auth_enabled: false
+
+promtail_server:
+  http_listen_port: 9080
+  grpc_listen_port: 0
+
+promtail_positions:
+  filename: "{{ promtail_var_path }}/positions.yaml"
+
+promtail_clients:
+  - url: http://localhost:3100/loki/api/v1/push
+
+# promtail_scrape_configs: []

roles/promtail/handlers/main.yaml

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+---
+- name: restart promtail
+  systemd:
+    name: promtail.service
+    daemon_reload: true
+    state: restarted

roles/promtail/tasks/configure.yaml

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+---
+- name: create group
+  group:
+    name: "{{ promtail_group }}"
+    system: true
+    state: "{{ promtail_group_state | default('present') }}"
+
+- name: create user
+  user:
+    name: "{{ promtail_user }}"
+    system: true
+    shell: "{{ promtail_user_shell }}"
+    group: "{{ promtail_group }}"
+    groups: "{{ promtail_groups }}"
+    createhome: false
+    home: "{{ promtail_var_path }}"
+    state: "{{ promtail_user_state | default('present') }}"
+
+- name: configure
+  template:
+    src: promtail.yaml.j2
+    dest: "{{ promtail_config_path }}"
+    owner: root
+    group: root
+    mode: 0444
+  notify: restart promtail
+
+- name: create var path
+  file:
+    path: "{{ promtail_var_path }}"
+    state: directory
+    owner: "{{ promtail_var_owner }}"
+    group: "{{ promtail_var_group }}"
+    mode: "{{ promtail_var_mode }}"
+
+- name: configure systemd template
+  template:
+    src: "{{ promtail_service_name }}.j2"
+    dest: "/etc/systemd/system/{{ promtail_service_name }}"
+    owner: root
+    group: root
+    mode: 0444
+  notify: restart promtail
+
+- name: manage service
+  service:
+    name: "{{ promtail_service_name }}"
+    enabled: "{{ promtail_service_enabled }}"
+    state: "{{ promtail_service_state }}"

roles/promtail/tasks/install.yaml

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+---
+- block:
+  - name: download archive
+    get_url:
+      url: "{{ promtail_release_url }}"
+      dest: "{{ promtail_download_path }}"
+      checksum: "{{ promtail_checksum }}"
+    register: dl
+    until: dl is success
+    retries: 5
+    delay: 10
+
+  - name: extract archive
+    unarchive:
+      src: "{{ promtail_download_path }}"
+      dest: "{{ promtail_unarchive_dest_path }}"
+      creates: "{{ promtail_extracted_path }}/promtail"
+      remote_src: true
+
+  - name: install binaries
+    copy:
+      src: "{{ promtail_extracted_path }}"
+      dest: "{{ promtail_bin_path }}/promtail"
+      owner: root
+      group: root
+      mode: 0755
+      remote_src: true
+    notify: restart promtail
+  when: promtail_version != promtail_local_version

roles/promtail/tasks/main.yaml

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+---
+- name: gather os specific variables
+  include_vars: "{{ lookup('first_found', possible_files) }}"
+  vars:
+    possible_files:
+      files:
+        - "{{ ansible_distribution }}-{{ ansible_distribution_version }}.yaml"
+        - "{{ ansible_distribution }}.yaml"
+        - "{{ ansible_os_family }}.yaml"
+        - "default.yaml"
+      paths:
+        - vars
+
+- name: include os specific tasks
+  include_tasks: "{{ lookup('first_found', possible_files) }}"
+  vars:
+    possible_files:
+      files:
+        - "{{ ansible_distribution }}-{{ ansible_distribution_version }}.yaml"
+        - "{{ ansible_distribution }}.yaml"
+        - "{{ ansible_os_family }}.yaml"
+        - "default.yaml"
+      paths:
+        - tasks
+
+- include: pre.yaml
+
+- include: install.yaml
+
+- include: configure.yaml

roles/promtail/tasks/pre.yaml

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+---
+- name: determine if installed
+  stat:
+    path: "{{ promtail_bin_path }}/promtail"
+  register: st
+
+- name: set promtail_installed
+  set_fact:
+    promtail_installed: "{{ st.stat.exists | bool }}"
+
+- block:
+  - name: determine latest version
+    uri:
+      url: https://api.github.com/repos/grafana/loki/releases/latest
+      return_content: true
+      body_format: json
+    register: _latest_version
+    until: _latest_version.status == 200
+    retries: 3
+
+  - name: set promtail_version
+    set_fact:
+      promtail_version: "{{ _latest_version.json['tag_name'] | regex_replace('^v', '') }}"
+
+- block:
+  - name: determine installed version
+    command: "{{ promtail_bin_path }}/promtail --version"
+    register: _installed_version_string
+    changed_when: false
+
+  - name: set promtail_local_version
+    set_fact:
+      promtail_local_version: "{{ _installed_version_string.stdout | regex_search(promtail_version_regex, '\\1') | first }}"
+  when: promtail_installed
+
+- name: set promtail_local_version to 0
+  set_fact:
+    promtail_local_version: "0"
+  when: not promtail_installed
+
+- block:
+  - name: get checksums
+    set_fact:
+      _checksums: "{{ lookup('url', promtail_checksum_url, wantlist=True) }}"
+
+  - name: set promtail_checksum
+    set_fact:
+      promtail_checksum: "sha256:{{ item.split(' ') | first }}"
+    loop: "{{ _checksums }}"
+    when: "promtail_release_file in item"

roles/promtail/templates/promtail.service.j2

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+{{ ansible_managed | comment }}
+
+[Unit]
+Description=Loki
+After=network-online.target
+
+[Service]
+Type=simple
+User={{ promtail_user }}
+Group={{ promtail_group }}
+ExecStart={{ promtail_bin_path }}/promtail \
+  -config.file {{ promtail_config_path }}
+WorkingDirectory={{ promtail_var_path }}
+
+Restart=always
+RestartSec=1
+
+[Install]
+WantedBy=multi-user.target

roles/promtail/templates/promtail.yaml.j2

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+{{ ansible_managed | comment }}
+---
+{% if promtail_server is defined %}
+server:
+  {{ promtail_server | to_nice_yaml(indent=2) | indent(2, False) }}
+{% endif -%}
+
+{% if promtail_positions is defined %}
+positions:
+  {{ promtail_positions | to_nice_yaml(indent=2) | indent(2, False) }}
+{% endif -%}
+
+{% if promtail_clients is defined %}
+clients:
+  {{ promtail_clients | to_nice_yaml(indent=2) | indent(2, False) }}
+{% endif -%}
+
+{% if promtail_scrape_configs is defined %}
+scrape_configs:
+  {{ promtail_scrape_configs | to_nice_yaml(indent=2) | indent(2, False) }}
+{% endif -%}