Expressions

Expressions is a powerful tool that allows formulating complex filters for playbook events. Playbook event filters use Common Expression Language (CEL).

The Common Expression Language (CEL) is a non-Turing complete language designed for simplicity, speed, safety, and portability. CEL's C-like syntax looks nearly identical to equivalent expressions in C++, Go, Java, and TypeScript.

Examples:

notify-with-filter.yaml

---
apiVersion: mission-control.flanksource.com/v1
kind: Playbook
metadata:
  name: notify-with-filter
spec:
  on:
    config:
      - event: created
  configs:
    - type: Kubernetes::Pod
  actions:
    - name: Send notification
      exec:
        script: notify-send "{{.config.name}} was created"
    - name: Bad script to create a failing action
      exec:
        script: non-existing-command
    - name: Send all success notification
      if: success() # this filter practically skips this action as the second action above always fails
      exec:
        script: notify-send "Everything went successfully"
    - name: Send notification regardless
      if: always()
      exec:
        script: notify-send "a config was created"

Context

Field	Description	Schema
config	Config passed to the playbook	ConfigItem
component	Component passed to the playbook	Component
check	Canary Check passed to the playbook	Check
params	User provided parameters to the playbook	map[string]string