How-to: Run a step depending on if the build is webhook triggered

Use case

You want to run a step only if the build is directly triggered by a webhook event, or only if it's started manually.

For example, you may have your Slack notifications set up as steps using the Slack notifier plugin within your pipeline in order to get more granular control over when and how these notifications are sent, and you want to send these notifications only if the build is automatically started via webhook, not when the build is manually triggered.

Solution:

To execute a step only when a build is manually triggered, you can create a condition to check for the value of the system-provided variable CF_BUILD_TRIGGER. This variable's value will be webhook if the build was started by a webhook event, and build if it was started manually (through UI, CLI, or API).

steps:
  SendToSlack:
    type: slack-notifier
    arguments:
      SLACK_HOOK_URL: '${{SLACK_WEBHOOK_URL}}'
      SLACK_TEXT: '${{SLACK_TEXT}}'
      SLACK_ATTACHMENTS: '${{SLACK_ATTACHMENTS}}'
  when:
    condition:
      all:
        webhookTriggered: '"${{CF_BUILD_TRIGGER}}" == "webhook"'

Similarly, you can match for the value build if you want to execute a step only if the build is manually initiated.

In child builds started with codefresh run, the value of CF_BUILD_TRIGGER will always be build. This is because although the parent build may be webhook-triggered, the child build is always started via API, which counts as a "manual" start.

To get around this, you can explicitly pass this variable from the parent to the child build to override the default value.

steps:
  run_child_pipeline:
    type: codefresh-run  
    arguments:
      ...
      VARIABLE:
        - CF_BUILD_TRIGGER=${{CF_BUILD_TRIGGER}}