yaml-update step syntax for conditionally selecting objects from arrays

[danielloader]

Quick question hopefully around how to use the yaml-update on selectors more complex than simple dot notation for objects.

Has anyone worked out the syntax for selecting a key in an object which is in an array?

I can select and replace it using yq on the terminal but using a yq path with a select component doesn't seem to work.

Given this example file:

example:
  nested:
    - id: a
      something: value
    - id: b
      something: value

How do I set the something value if id == a?
Here's the example using the yq CLI to achieve an update on a key in this way.

yq '(.example.nested[] | select(.id == "a") | .something) = "abc"' test.yaml
example:
  nested:
    - id: a
      something: abc
    - id: b
      something: value

[krancour]

Nothing that sophisticated is possible yet, but I'd like to get there.

yaml-update is a stripped down and renamed clone of the deprecated helm-image-update step.

The most important requirement when we first wrote that was that existing comments and formatting choices in the YAML file be preserved. We didn't readily find a library that could handle that. Kustomize has some stuff internally that may be useful for this purpose, but at the time, we couldn't really get it working. So we rolled our own lib for updating values in a YAML file, but for the narrow use of updating something like image.tag, there wasn't any need to support anything as complex as yq expressions...

Now that we've generalized the helm-image-update step, support for more complex expressions seems to be in order. This isn't something we'd want to roll ourselves -- so I will re-survey the landscape for yaml libs that can both support expressions and meet the requiremen of preserving comments and formatting choices in the file that's being updated.