yaml-update one block in a list

[david-curran-90]

I need to update a yaml file that contains a list of multiple blocks

e.g.

tenants:
  - name: tenant1
     key: value
  - name: tenant2
     key: value

In my promotion I want to update the key where name = tenant2. How can I achieve this with the yaml-udpate step?

My thought was something like this

- uses: yaml-parse
  as: values
  config:
    path: './src/values.yaml'
    outputs:
    - name: index
      fromExpression: tenants.[name=tenant2]
- uses: yaml-update
  config:
    path: ./src/values.yaml
    updates:
    - key: tenants.${{ task.outputs['values'].index }}
      value: "newvalue"

Is something like this possible? perhaps there is a more Kargo-like solution?

[krancour]

Kargo's docs claim compatibility with this: https://github.com/tidwall/sjson?tab=readme-ov-file#path-syntax, although, in fact, there are very minor differences -- none however that should impact you here.

I believe this is what you are looking for:

- uses: yaml-update
  config:
    path: ./src/values.yaml
    updates:
    - key: tenants.1.key
      value: newValues

[david-curran-90]

Thanks @krancour my issue is how to get the index that I require. Which value I want to change depends on the name value so if name = tenant1 then I'd want to update index 0. How would I figure out which index to use?

[krancour]

I want to update the key where name = tenant2.

Sorry! I'd misunderstood that as one human telling another which part of the example doc is to be updated, for clarity. It had not clicked that you weren't always looking to modify one specific element of the sequence.

I get it now.

I'm afraid I don't have a good answer for you here.

I can actually point you to the fact of there being an entirely separate promotion step for updating Helm subchart dependencies in a Chart.yaml because it's the same exact problem. Dependencies are a list. We could figure out which one to update by looking at the url and name in the elements of the list, but we don't want to assume the list is in a specific order that never changes.

☹️

There may be a clever expression-based way of approaching this that I've not yet noticed.

My thought was something like this

Did that example:

• Not work?

OR

• Worked, but you're looking for something cleaner?

[david-curran-90]

Yeah we have a separate step for updating helm charts and we build the stage with templating that contains a for loop to add a step for each dependency :D I wanted to avoid that here as this list is likely to be more dynamic than a set of helm chart deps

I haven't actually tried my own thought out yet, wanted to gather information before comiting to the effort. Guess I'll try it and see what happens. Thanks for your replies

[david-curran-90]

As far as I can tell this is not possible. However I've found a simpler route anyway using yaml anchors :) Now I just update known locations in my yaml file and everything else can alias that

e.g.

instead of

tenants:
  - name: tenant1
     key: value
  - name: tenant2
     key: value

I have

values:
  dev: &1.2.0
  prod: &1.1.2
tenants:
  - name: tenant1
     key: *dev
  - name: tenant2
     key:*prod

[david-curran-90]

Now I have a problem of writing an anchor into the yaml 😠

[david-curran-90]

Just had to tweak my schema a little so Kargo is updating a field in the anchored yaml

values:
  dev: &dev
    value: 1.2.0
  prof: &prod
    value: 1.1.2
tenants:
  - name: tenant1
     values: *dev
  - name: tenant2
     values: *prod

Which essentially results in this

tenants:
  - name: tenant1
     values:
       value: 1.2.0
  - name: tenant2
     values:
       value: 1.1.2

Then Kargo uses the yaml-update step to set values.dev.value and values.prod.value in different stages :)