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Ansible role for munin-async agent

This Ansible role installs and configure munin-async, a monitoring agent that complements munin-node.

Compared to a bare munin-node setup, the addition of munin-async allows to:

  • fetch data over SSH instead of the insecure TCP-based communication protocol used by munin-node
  • fetch data asynchronously: the munin-async agent will poll the local munin-node every 5 minutes and persist the resulting data, allowing a munin master to fetch data from munin-async at any time (e.g. every 30 minutes)

See the Munin documentation on munin-async for a more complete overview.

Features and overview

This role does only two things, but does them well:

  • install munin-async and munin-node on a target system, with support for several operating systems
  • copy the public SSH key of the munin master so that it can fetch data from this target system

It is recommended to use a separate role to configure munin-node to your liking, such as the munin-node role from geerlingguy.

Configuration of the munin master needs to be done separately.

Installation

This role is available on Ansible Galaxy

Requirements

This role has been tested to run on Debian (from wheezy to bullseye), Ubuntu, CentOS 7 and 8, Fedora, and OpenBSD.

It should also work on all other Debian-derivatives and RedHat-derivatives.

Role variables

This role has a single variable:

munin_async_sshpubkeys: []

A list of SSH public keys that will be installed in the munin-async user home, to allow the munin master node to connect via SSH.

How to use

Start by generating a pair of SSH keys on your munin master:

$ sudo -u munin ssh-keygen
$ cat /var/lib/munin/.ssh/id_rsa.pub

On your ansible controller, add this SSH key to the munin_async_sshpubkeys variable. This can be done either through a group_vars file, or directly in your playbook. Assuming you have a group named monitorednodes:

# Playbook: munin-async.yml
- hosts: monitorednodes
  vars:
    munin_async_sshpubkeys: ["ssh-rsa AAAAB3NzaC1y...m/mRpZR munin@munin-master"]
  roles:
    - { role: munin-async }

Apply this playbook to your nodes:

$ ansible-playbook munin-async.yml

This will install and configure munin-async with the SSH key of the munin master.

Finally, on your munin master, you need to declare each node that needs to be monitored:

# /etc/munin/munin-conf.d/machines.conf
[foo.example.com]
  address ssh://[email protected]:22
  use_node_name yes

Of course, you could write a simple role/playbook to manage that through ansible as well.

Hacking

Adding support for an OS

To add support for a new OS, the first step is to add variables in vars/OSFAMILY.yml where OSFAMILY is what ansible reports as ansible_os_family. For example:

munin_async_service: munin-asyncd
munin_async_clientbin: /usr/share/munin/munin-async
munin_async_user: munin-async
munin_async_group: munin-async
munin_async_home: /var/lib/munin-async

These variables should match the munin-async package for the OS where applicable.

If no user is created by the package, the username and home can be chosen arbitrarily. It is recommended to use munin-async for consistency (to help configure the munin master in an uniform way). This user should have read access to the munin-async data, e.g. /var/lib/munin-async/ on Debian or /var/lib/munin/spool/ on Red-Hat systems.

Then, add a file tasks/install-YOUROS.yml that should:

  • install an appropriate munin-async package (or even install it manually)
  • if necessary, create a user named {{ munin_async_user }} with home directory {{ munin_async_home }}
  • if necessary, create a service named {{ munin_async_service }} to start/stop the daemon

Lastly, include this file in the main tasks file with the right conditional.

License

MIT