ansible-events

• Free software: Apache Software License 2.0
• Documentation: https://ansible-events.readthedocs.io.

Event driven automation for Ansible.

The real world is fully of events that change the state of our software and systems. Our automation needs to be able to react to those events. Ansible-events is a command line tool that allows you to recognize which events that you care about and react accordingly by running a playbook or other actions.

Let's get started with a simple hello world example to familiarize ourselves with the concepts:

---
- name: Hello Events
  hosts: localhost
  sources:
    - benthomasson.eda.range:
        limit: 5
  rules:
    - name: Say Hello
      condition: event.i == 1
      action:
        run_playbook:
          name: benthomasson.eda.hello
...

Events come from a event source and then are checked against rules to determine if an action should be taken. If the condition of a rule matches the event it will run the action for that rule.

In this example the event source is the Python range function. It produces events that count from i=0 to i=<limit>.

When i is equal to 1 the condition for the the Say Hello rule matches and it runs a playbook.

Normally events would come from monitoring and alerting systems or other software. The following is a more complete example that accepts alerts from Alertmanager:

---
- name: Automatic Remediation of a webserver
  hosts: all
  sources:
    - name: listen for alerts
      benthomasson.eda.alertmanager:
        host: 0.0.0.0
        port: 8000
  rules:
    - name: restart web server
      condition: event.alert.labels.job == "fastapi" and event.alert.status == "firing"
      action:
        run_playbook:
          name: benthomasson.eda.start_app
...

This example sets up a webhook to receive events from alertmanager and then matches events where the fastapi job alert has a staus of firing. This runs a playbook that will remediate the issue.

Features

• Conditionally launch playbooks based on rules that match events in event streams.

Examples

Rules are organized into rulesets using a syntax that is similar to ansible-playbooks:

---
- name: Hello Events
  hosts: localhost
  sources:
    - benthomasson.eda.range:
        limit: 5
  rules:
    - name: Say Hello
      condition: event.i == 1
      action:
        run_playbook:
          name: benthomasson.eda.hello
...

Each ruleset defines: a set of hosts to pass to the playbook, a set of event sources, and a set of rules. The set of hosts is the normal hosts pattern from ansible playbooks. The event sources are a new type of plugin that subscribe to events from event streams. The rules have conditions that match values in the events and actions that can run playbooks, assert facts, retract facts, and print information to the console.

Let's look closer at the event source:

- benthomasson.eda.range:
    limit: 5

This section of YAML defines that an event source plugin from the benthomasson.eda should be loaded and given the arguments: limit=5. This source will generate a range of numbers from zero to 4 and then exit.

The rules YAML structure looks like the following:

- name: Say Hello
  condition: event.i == 1
  action:
    run_playbook:
      name: benthomasson.eda.hello

This block of YAML defines a rule with name "Say Hello", a condition that matches when an event has an value "i" that is equal to 1, and an action that runs a playbook inside the collection benthomasson.eda.

Credits

This package was created with Cookiecutter and the audreyr/cookiecutter-pypackage project template.