This role is abandoned.

Monit

Performs installation and configuration of Monit service.

Provides an action plugin to facilitate configuration of checks. See below for details.

This role is Work In Progress. See TODO file for some details.

It's fair to say that the whole action plugin implementation is quite hacky and fragile.

• Ansible doesn't support action plugins in roles. See this thread for details.
• The plugin does its best to notify the restart handler, by hijacking Ansible's callback_plugins stack.

Requirements

Since Ansible doesn't support action plugins in roles, it is needed to explicitly add the path to this role's action plugins in ansible.cfg.

Example:

action_plugins = ./contrib/roles/sbitmedia.monit/action_plugins

Happily, action_plugins supports relative paths. Paths are separated by colon (:).

Role Variables

The role provides sane defaults, and respects configuration files provided by the OS whenever possible.

Default variables are documented in defaults/main.yml.

Role variables are set per OS. See: vars/*.yml.

See also the args accepted by monit_check in library/monit_check.

Example Usage

Using the role is straightforward, just include it and set overrides as needed.

Following playbook shows several examples of monit_check usage. In a bird-eye view it does the folliwing:

• Declare two variables with configuration data for several checks.
• includes the role.
• performs four tasks showing different ways to use monit_check.

- hosts: servers
  vars:
    monit_check_system_resource_tests:
      - type: 'loadavg(1min)'
        operator: '>'
        value: 24
        tolerance:
          times: 3
          cycles: 5
      - type: 'loadavg(5min)'
        operator: '>'
        value: 12
      - type: 'memory'
        operator: '>'
        value: 75%

    monit_check_filesystems:
      - name: rootfs
        path: /
        tests:
          - type: fsflags
          - type: permission
            value: '0755'
          - type: space
            operator: '>'
            value: 80%

  roles:
    - sbitmedia.monit

  tasks:
    - name: Monit check for ntp service.
      monit_check:
        type: service
        name: ntpd

    - name: Monit check for ssh service.
      action: monit_check type=service name=ssh
      when: monit_service is defined

    - name: Ensure monit system check
      action: monit_check
      args:
        type: system
        tests: "{{ monit_check_system_resource_tests }}"
      when: monit_service is defined

    - name: Ensure monit filesystems check
      action: monit_check
      args:
        type: filesystem
        name: "{{ item.name }}"
        path: "{{ item.path }}"
        tests: "{{ item.tests }}"
      with_items: monit_check_filesystems
      when: monit_service is defined

Notes:

• monit_check actions needs the role to be included before. If want to use monit_check inside your own roles, read below section Leverage monit role.
• action: monit_check with when: monit_service is defined is useful for a soft dependency on the role. This makes sense when using monit_check in a role that doesn't know if sbitmedia.monit is available.
• monit_service is a variable defined in the role. If the variable is defined, the role is present, and running the task makes sense.

Leverage monit in your roles

Sumarizing above notes. There's two ways to leverage this role in your own roles.

• Hard dependency: add sbitmedia.monit as a dependency in your role and start ruling your own checks with no drawbacks at all.

• Soft dependency: use sbitmedia.monit when it is available. For this to work, several thing need to happen:

1. the role must be included before yours.
2. calls to monit_check must be done this way, to avoid syntax errors in Ansible:

- name: Ensure monit system check
  action: monit_check
  args:
    type: system
    tests: "{{ monit_check_system_resource_tests }}"
  when: monit_service is defined

You can see a full-fledged pattern for integration of external services in sbitmedia.fail2ban. See its main.yml along with external.yml and external/*.

License

BSD

Author Information

Jonathan Araña Cruz - SB IT Media, S.L.