Warning when dashboard with visualisations by reference instead of value exist

[ruflin]

In Kibana, dashboards can be built with visualisations inside stored by value or by reference. Historically only by reference was supported so most of our dashboards still use by reference. The goal is to move to by value to have dashboards and visualisations directly bundled together as a unit which speeds up the installation of it in Fleet and also makes sure the visualisations do not all show up in the search, only the dashboard.

To help with this effort and notify engineers about usage of by reference, it would be nice if during building a package, package-spec or the build process would show a warning if a visualisation in a dashboard is added by reference instead of by value. Changes should not be blocked on this but engineers notified about it.

This is related to elastic/kibana#129303 which should help engineers with an easy migration to by value.

[mrodm]

I was checking the references that could be defined in dashboards, and currently these are the reference types that I found across all the packages:

• dashboard
• index-pattern
• lens
• map
• search
• tag
• visualization

In #389 , just "lens" and "visualization" reference types were considered to show the warning. What other reference types should be checked to show this warning ?

I've been testing to add more elements to one dashboard by reference (in Kibana 8.0.0):

• I was able to create a "map" reference from the dashboard edit view, and then unlink it.
• Not sure "index-pattern" should be shown as a warning. In one of the dashboards that I did lately, that reference appeared even when all the visualizations were added by value.
• Regarding "search", I was just able to add it from the library creating it previously in Discover. So I think there should not be needed a warning there.
• "Tags" need to be created in advance (in Stack management), so I guess they should be always created as a reference.
• I was not able to create a reference of type "dashboard".

@ruflin With that, should we consider to update this warning and show it just when there are references of types lens, visualization and maps?

[ruflin]

@flash1293 Could you comment on the above. Should we strive for all assets to added by value? Is it even possible for all assets? Lets ignore index-patterns / data views for a moment as we will have a follow up discussion on that.

[flash1293]

lens, visualization and map can go "by-value". All other types need to go by reference for now (excluding the data view discussion)

[mrodm]

Perfect, I'll update the validation rule adding "map" here #414
Thanks @ruflin and @flash1293 !