Beacons#

Use case#

Beacons are a monitoring tool that is set up on the salt-minion process to expand its utility. Beacons can reduce the need for user-triggered configuration and management because they enable autonomous monitoring and event publishing that are triggered by designated system processes.

Beacons

Beacons can be leveraged for a number of purposes:

  • Automated reporting
  • Error log delivery
  • Microservice monitoring
  • User shell activity
  • Resource monitoring

When coupled with reactors, an additional Salt master side feature, beacons can create automated pre-written responses to infrastructure and application issues.

Minion configuration#

When configuring the beacon on the Salt minion, no modification to the intended process monitoring needs to take place.

The disable_during_state_run argument may be set. If a state run is in progress, the beacon will not run on its regular interval until the minion has completed the state run, at which point the normal beacon interval will resume.

/etc/salt/minion.d/beacons.conf#
 beacons:
   inotify:
     - files:
         /etc/named.conf:
            mask:
              - close_write
              - create
              - delete
              - modify
        /etc/named/zones:
            mask:
              - close_write
              - create
              - delete
              - modify
     - disable_during_state_run: True
 service:
   - services:
       named:
         onchangeonly: True
 diskusage:
   - /: 50%
   - /var: 90%
   - interval: 120

When you are developing a beacon, if you need additional logic to execute, such as closing file handles for the disable_during_state_run, you can add a close() function to the beacon.

Beacon published events#

When using the beacon to observe a process, the external events are converted to a dictionary report for the event bus on the master.

The previous configuration would trigger an event such as:

salt/beacon/20190418-sosf-ubuntu/diskusage/ {
    "_stamp": "2019-05-06T18:52:14.288448",
    "diskusage": 85.5,
    "id": "20190418-sosf-ubuntu",
    "mount": "/"
}
salt/beacon/20190418-sosf-master/inotify//etc/named.conf {
    "_stamp": "2019-05-06T19:30:35.397508",
    "change": "IN_IGNORED","id": "20190418-sosf-master",
    "path": "/etc/named.conf"
}

Managing at the terminal#

Beacons for minions can be added in the Salt master terminal. However, this will only load the beacon into memory on the Salt minion.

salt '*' beacons.add ps "{'salt-master':'stopped', 'apache2':'stopped'}"

To keep a beacon persistent after deployment from the terminal, you can have the beacon written to YAML in /etc/salt/minion.d/beacons.conf on the minion.

salt '*' beacons.save

A list of beacons can be generated by running:

salt '*' beacons.list

Run the following to delete a beacon:

salt '*' beacons.delete ps

Beacons disabled individually or collectively:

salt '*' beacons.disable_beacon ps
salt '*' beacons.disable

Beacons enabled individually or collectively:

salt '*' beacons.enable_beacon ps
salt '*' beacons.enable

Pillar deployed beacon#

Beacons can be deployed to minions, using pillar configurations that target the minions that should receive the beacon.

When set in pillar, the beacon should then be added to the pillar top file, to target specific minions that should have the beacon configuration.

/srv/pillar/load_beacon.sls#
beacons:
  load:
    - 1m:
      - 0.0
      - 2.0
    - interval: 10

The top file would then target minions for this beacon:

:caption: /srv/pillar/top.sls

base:
  '*':
    - load_beacon

Updating the pillar will deliver the beacon to the minion in memory:

salt \* saltutil.refresh_pillar
salt \* beacons.list
rebel_01:
    beacons:
      load:
      - 1m:
        - 0.0
        - 2.0
      - interval: 10

Then save the beacon to the filesystem for permanents:

salt \* beacons.save
rebel_01:
    ----------
    comment:
       Beacons saved to /etc/salt/minion.d/beacons.conf.
    result:
       True

State deployed beacon#

Another method to deploy beacons is to use states with a normal file.managed operation. As a best practice, the beacon.conf file will sit next to the managing Salt state for deployment.

/srv/salt/beacons/beacons.conf#
beacons:
  load:
    - 1m:
      - 0.0
      - 2.0
    - interval: 10
/srv/salt/beacons/init.sls#
add_load_beacon:
  file.managed:
    - name: /etc/salt/minion.d/beacons.conf
    - source: salt://beacons/beacons.conf

min_restart_for_load_beacon:
  cmd.run:
    - name: 'systemctl restart salt-minion'

Running the beacon job will result in the salt-minion failing to return a job report to the salt-master, because of restarting to have the beacon configuration loaded:

salt rebel_01 state.sls beacons
rebel_01:
    Minion did not return. [No response]

After allowing a moment for the salt-minion to restart, you can see its functioning with the beacons module:

salt rebel_01 test.version
rebel_01:
   2019.2.3

salt rebel_01 beacons.list
rebel_01:
   beacons:
   load:
   - 1m:
     - 0.0
     - 2.0
   - interval: 10