Fix error during expansion of !!merge <<: anchor tags

[RafaeLeal]

Problem

Using yamls with <<: *anchor with or without the tag !!merge tag is leading to an error:

json: unsupported type: map[interface {}]interface {}

A lot of apps distributes YAMLs that use that, so even if you're not using it, you may rely on some distribution like Tekton's or Knative's:

• https://storage.googleapis.com/tekton-releases/pipeline/previous/v0.22.0/release.yaml
• https://github.com/knative/eventing/releases/download/v0.26.0/eventing-core.yaml

Solution

I'm not familiar with the code base, but I tried to understand where we were doing the de-anchoring following this PR
https://github.com/kubernetes-sigs/kustomize/pull/4187/files

Related Issues

• Error during expansion of "!!merge <<:" anchor tags #4212
• Merge Key Language-Independent Type support for YAML anchor/alias #4215

[k8s-ci-robot]

@RafaeLeal: This PR has multiple commits, and the default merge method is: merge.
You can request commits to be squashed using the label: tide/merge-method-squash

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[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Rafael Leal (a23d598, b2cdf1d, 3b5403a, fa352cb, 7895a86, 2c80158, 5d6137a, 5c24ab3, 20363a2)

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[RafaeLeal]

/label tide/merge-method-squash

[RafaeLeal]

I believe we have two corner cases that we need to take a look:
One is that we're currently removing comments because we are rebuilding that node structure, and other is that we are no longer serializing json correctly.

The first one I believe we can manage, just need to think about the possible cases. We could have, as simple comment as possible:

apiVersion: v1
kind: MergeTagTest
metadata:
  name: test
spec:
  color:
    # red color
    rgb: "#FF0000"

And that is simple enough, but we could also have comments on merge tags, and we need to think about it.

apiVersion: v1
kind: MergeTagTest
metadata:
  name: test
spec:
  color: &base-color
    # red color
    rgb: "#FF0000"
  primaryColor:
    # use the same base color
    <<: *base-color

and then we expand, we should decide:

• Should we keep comments at all?
• Should we copy the comments when de-anchoring?
• How we are going to merge comments?

On merge comments, we have some other corner cases:

• merging line comments

color: &base-color
  rgb: "#FF0000" # red color
primaryColor:
  <<: *base-color # use same base color 

We have a couple of options.. we could transform to head comment.. and we can decide if we want to transform one or both:

color: 
  rgb: "#FF0000" # red color
primaryColor:
  # red color
  rgb: "#FF0000" # use same base color 

we could also adopt a delimiter

primaryColor:
  rgb: "#FF0000" # red color; use same base color 

• ordering problem

color: &base-color
  # red color
  rgb: "#FF0000" 
primaryColor: &primary-color
  # use same base color
  <<: *base-color  
  alpha: 0.5
secondaryColor:
  # mixing colors
  <<: *base-color
  <<: *primary-color

If we do decide to copy the comments, we are going to need to deal with how we order that.. and we can just get all merge comments on top of the mapping node.

secondaryColor:
  # red color
  # use same base color
  # mixing colors
  rgb: "#FF0000"
  alpha: 0.5

Let me know what you think

[RafaeLeal]

On the other problem, it seems that for some reason I broke the json serialization.. It's failing the TestMoreRNodesFromBytes/goodJson test and other related ones.. I'm not sure how json is dealt, but I'm assuming I broke some metadata when rebuilding the node structure.

[natasha41575]

/cc
/cc @KnVerey

[RafaeLeal]

On the other problem, it seems that for some reason I broke the json serialization.. It's failing the TestMoreRNodesFromBytes/goodJson test and other related ones.. I'm not sure how json is dealt, but I'm assuming I broke some metadata when rebuilding the node structure.

I managed to fix this adding a new yaml filter MapEntrySetter... this way we can keep the same Style

[natasha41575]

/ok-to-test

[KnVerey]

I have a couple new observations, but only the question about unhandled errors is a blocker for me. Otherwise this is ready to go!

[KnVerey]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: KnVerey, RafaeLeal

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