Track the last time when the entity was changed

Feature Suggestion

Track the last time when the entity was changed

Possible Implementation

Maybe a new db field like last_changed_at can be added in refresh_state database table. Once an entity has been discovered, maybe based on whether the result_hash in refresh_state table is changed, the last_changed_at can be updated accordingly.

Context

This will help track the freshness of the entity. If an entity was not updated for 1 month, it can be considered as outdated. We are trying to improve the entity update process like notifying entity owners if they haven’t update their entity for long time.

[freben]

I’m arguing that instead, we should first make sure to track this in the catalog database tables. Putting (especially time based) volatile information in the catalog entities is probably unfortunate. Either way, after we have this info in the database, we could consider reading it up and adding it to entities as part of the stitching step later on.

Main task is to add columns to the proper tables (see the migrations directory), and then to make sure to write to those columns in the required places (see especially the DefaultEntitiesCatalog and Stitcher classes).

[Rugvip]

This might be as simple as adding the current timestamp to the entity around here. I think I’d vote for an annotation, e.g. backstage.io/updated-at. Not sure if it’s worth backfilling, but it could be done using a database migration of the final entities table.

Is it worth it? What do you think @backstage/catalog-core?