Expand a flat list of yaml keys to a structure

[chlab]

I would like to be able to expand a flat list of yaml keys to a yaml structure, for example:

Input:

foo.bar.baz
foo.bar.boo
bar.foo

Output:

foo:
  bar:
    baz: null
bar:
  foo: null

My use case for this is to extract a list of values from a helm chart and then generate a dummy values file for it, e.g.:

grep -o '\.Values\.[^ }]*' my-template.yaml | sort | uniq | sed 's/\.Values\.//' | yq xy

Is this maybe even possible already? I didn't see anything that would indicate so in the docs.

[mikefarah]

If you convert it to a valid yaml list of path expressions:

- .foo.bar.baz
- .foo.bar.boo
- .bar.foo

Then you can use ireduce and eval:

echo "foo.bar.baz
foo.bar.boo
bar.foo" | sed -e 's/^/- \./' | yq '.[] as $i ireduce({}; eval($i) = null)'

[mikefarah]

foo:
  bar:
    baz: null
    boo: null
bar:
  foo: null

[chlab]

Works, thanks @mikefarah!

For anyone stumbling on this in the future who's interested - this is the command I'm now using:

grep -o '\.Values\.[^ }]*' my-template.yaml | sort -u | sed 's/^\.Values\./- ./' | yq '.[] as $i ireduce({}; eval($i) = null)'

Which will find all occurrences of .Values.something.other in a file, sort it, make it unique and convert it to a valid yaml structure.