Tags on Catalog Entities

Feature Suggestion

Add the ability to put user defined tags on catalog entities.

These are single-valued strings in essence, to for example classify entities in various ways. This is different to the labels in metadata.labels that are key-value pairs.

Possible Implementation

We have been discussing back and forth whether tags should be complex and supporting metadata of their own - perhaps colors, description etc. This would probably entail inventing a Tag entity kind or similar, that other entities can reference. We have decided against that at least in the initial implementation, in the name of simplicity, until we know more about how the feature will be used in the wild.

Therefore, we propose that tags are simply added as a lightweight optional list of strings to the base shared metadata structure.

Example:

metadata:
  name: my-component
  tags:
    - java
    - edge

As discussed in #1947, this is compatible with a future extension to the model where these strings could be interpreted as refs (with an implicit kind and namespace) to a more metadata-rich tag kind. But for now they are just read as-is, as plain strings.

Mockup of how this could look when shown in the Backstage Service Catalog:

[stefanalund]

In addition, I wonder how to handle the casing of the tags. In the example entity the tags are all lower case, in the mockup the start with a capital letter. For the start I would go with no extra handling, but we could extend that later.

@Fox32 personally I think forcing lower case makes sense.

Do you have a suggestion how it should look on the entity details page?

@katz95 could you help with this question? Pretty sure we don’t have a mockup of this. Feels natural to include it in the “Information” card though. @Fox32 to unblock you, I would suggest to start with just adding it to the Service Catalog table, as outlined in the above mockup.

[Fox32]

@Fox32 personally I think forcing lower case makes sense.

I will go with the existing isValidDnsLabel validation.