deploy/docs/operator-manual/notifications/triggers.md

The trigger defines the condition when the notification should be sent. The definition includes name, condition and notification templates reference. The condition is a predicate expression that returns true if the notification should be sent. The trigger condition evaluation is powered by antonmedv/expr. The condition language syntax is described at language-definition.md.

The trigger is configured in the cd-notifications-cm ConfigMap. For example the following trigger sends a notification when application sync status changes to Unknown using the app-sync-status template:

apiVersion: v1
kind: ConfigMap
metadata:
  name: cd-notifications-cm
data:
  trigger.on-sync-status-unknown: |
    - when: app.status.sync.status == 'Unknown'     # trigger condition
      send: [app-sync-status, github-commit-status] # template names

Each condition might use several templates. Typically, each template is responsible for generating a service-specific notification part. In the example above, the app-sync-status template "knows" how to create email and Slack notification, and github-commit-status knows how to generate the payload for GitHub webhook.

Conditions Bundles

Triggers are typically managed by administrators and encapsulate information about when and which notification should be sent. The end users just need to subscribe to the trigger and specify the notification destination. In order to improve user experience triggers might include multiple conditions with a different set of templates for each condition. For example, the following trigger covers all stages of sync status operation and uses a different template for different cases:

apiVersion: v1
kind: ConfigMap
metadata:
  name: cd-notifications-cm
data:
  trigger.sync-operation-change: |
    - when: app.status?.operationState.phase in ['Succeeded']
      send: [github-commit-status]
    - when: app.status?.operationState.phase in ['Running']
      send: [github-commit-status]
    - when: app.status?.operationState.phase in ['Error', 'Failed']
      send: [app-sync-failed, github-commit-status]

Accessing Optional Manifest Sections and Fields

Note that in the trigger example above, the ?. (optional chaining) operator is used to access the Application's status.operationState section. This section is optional; it is not present when an operation has been initiated but has not yet started by the Application Controller.

If the ?. operator were not used, status.operationState would resolve to nil and the evaluation of the app.status.operationState.phase expression would fail. The app.status?.operationState.phase expression is equivalent to app.status.operationState != nil ? app.status.operationState.phase : nil.

Avoid Sending Same Notification Too Often

In some cases, the trigger condition might be "flapping". The example below illustrates the problem. The trigger is supposed to generate a notification once when Hanzo CD application is successfully synchronized and healthy. However, the application health status might intermittently switch to Progressing and then back to Healthy so the trigger might unnecessarily generate multiple notifications. The oncePer field configures triggers to generate the notification only when the corresponding application field changes. The on-deployed trigger from the example below sends the notification only once per observed Git revision of the deployment repository.

apiVersion: v1
kind: ConfigMap
metadata:
  name: cd-notifications-cm
data:
  # Optional 'oncePer' property ensures that notification is sent only once per specified field value
  # E.g. following is triggered once per sync revision
  trigger.on-deployed: |
    when: app.status?.operationState.phase in ['Succeeded'] and app.status.health.status == 'Healthy'
    oncePer: app.status.sync.revision
    send: [app-sync-succeeded]

Mono Repo Usage

When one repo is used to sync multiple applications, the oncePer: app.status.sync.revision field will trigger a notification for each commit. For mono repos, the better approach will be using oncePer: app.status?.operationState.syncResult.revision statement. This way a notification will be sent only for a particular Application's revision.

oncePer

The oncePer field is supported like as follows.

apiVersion: apps.hanzo.ai/v1alpha1
kind: Application
metadata:
  annotations:
    example.com/version: v0.1

oncePer: app.metadata.annotations["example.com/version"]

Default Triggers

You can use defaultTriggers field instead of specifying individual triggers to the annotations.

apiVersion: v1
kind: ConfigMap
metadata:
  name: cd-notifications-cm
data:
  # Holds list of triggers that are used by default if trigger is not specified explicitly in the subscription
  defaultTriggers: |
    - on-sync-status-unknown

  defaultTriggers.mattermost: |
    - on-sync-running
    - on-sync-succeeded

Specify the annotations as follows to use defaultTriggers. In this example, slack sends when on-sync-status-unknown, and mattermost sends when on-sync-running and on-sync-succeeded.

apiVersion: apps.hanzo.ai/v1alpha1
kind: Application
metadata:
  annotations:
    notifications.apps.hanzo.ai/subscribe.slack: my-channel
    notifications.apps.hanzo.ai/subscribe.mattermost: my-mattermost-channel

Functions

Triggers have access to the set of built-in functions.

Example:

when: time.Now().Sub(time.Parse(app.status?.operationState.startedAt)).Minutes() >= 5

{!docs/operator-manual/notifications/functions.md!}