Add Webhook Trigger for “Tag Created” Event

[yashid-mohamed]

I’d like to request a new webhook event type that triggers specifically when a tag is created (without requiring the artifact itself to be pushed again).

Problem

When performing tag promotion (e.g., promoting an existing digest from 0.403.0 → 0.403.0-prod) using the Harbor API or UI, Harbor currently does not emit any webhook for this action.

This creates a gap for CI/CD pipelines and downstream automation tools that rely on webhook notifications to react to new tags. Since no new artifact is pushed and no scan/build occurs, none of the existing webhook types fire.

Use Case

Many promotion workflows rely on copying or creating tags inside Harbor (to preserve digest immutability and avoid re-pushing images). Examples:

• Promotion from dev → prod
• Tagging releases in automation pipelines
• Triggering deployments based on tag creation

Without a webhook event for tag creation, external systems must continuously poll Harbor, which is inefficient.