I need to perform what you might call a deep merge between two YML files.
Where there are two matching paths the child nodes should be aggregated, that includes array values. Where there is a path match on a terminal node the value from the second file wins.
For exmaple:
INPUT: a.yml
a:
a:a
b:b
b:
a:a
INPUT: b.yml
a:
a:1
c:1
c:
a:1
REQUIRED OUTPUT:
a:
a:1
b:b
c:1
b:
a:a
c:
a:1
The closest I have got to this using yq is:
yq eval-all '. as $item ireduce ({}; . *+d $item )' *.yml
a: a:1 c:1
b: a:a
c: a:1
as you can see a: branch is replaced entirely from the root.
>Solution :
YAML requires at least one whitespace character after the : to make it an object with key and value. In your sample file a.yml containing
a:
a:a
b:b
the value of .a is simply the string a:a b:b. There are no paths .a.a or .a.b.
With the necessary whitespace added, your attempt works as expected (spelling out the input file arguments because order matters: the latter will overwrite the former).
yq eval-all '. as $item ireduce ({}; . *+d $item )' a.yml b.yml
a:
a: 1
b: b
c: 1
b:
a: a
c:
a: 1
Tested with mikefarah/yq v4.35.1