Merge

Merge multiple yaml files into a one

Yaml files can be merged using the 'merge' command. Each additional file merged with the first file will set values for any key not existing already or where the key has no value.

yq m <yaml_file> <yaml_file2> <yaml_file3>...

Merge example

Given a data1.yaml file of:

a: simple
b: [1, 2]

and data2.yaml file of:

a: other
c:
  test: 1

then

yq merge data1.yaml data2.yaml

will output:

a: simple
b: [1, 2]
c:
  test: 1

Updating files in-place

yq m -i data1.yaml data2.yaml

will update the data1.yaml file with the merged result.

Overwrite values

Given a data1.yaml file of:

a: simple
b: [1, 2]
d: left alone

and data2.yaml file of:

a: other
b: [3, 4]
c:
  test: 1

then

yq m -x data1.yaml data2.yaml

will output:

a: other
b: [3, 4]
c:
  test: 1
d: left alone

Notice that 'b' does not result in the merging of the values within an array.

Append values with arrays

Given a data1.yaml file of:

a: simple
b: [1, 2]
d: hi

and data2.yaml file of:

a: something
b: [3, 4]
c:
  test: 2
  other: true

then

yq m --arrays=append data1.yaml data2.yaml

will output:

a: simple
b: [1, 2, 3, 4]
c:
  test: 2
  other: true
d: hi

Note that the 'b' array has concatenated the values from the second data file. Also note that other map keys are not overridden (field a).

Auto-create

By default, yq will automatically create any missing entries in the target yaml file. This can be turned off so that only matching paths are merged in. When turned off - you will most likely want to use the override flag.

Given a data1.yml file of:

a: thing
b: something else

and data2.yml file of:

b: new value
d: not in original

Then

yq m --overwrite --autocreate=false data1.yml data2.yml

will yield

a: thing
b: new value

Multiple Documents

Merge into single document

Currently yq only has multi-document support for the first document being merged into. The remaining yaml files will have their first document selected.

Given a data1.yaml file of:

something: else
---
a: simple
b: cat

and data3.yaml file of:

b: dog

then

yq m -x -d1 data1.yaml data3.yaml

will output:

something: else
---
a: simple
b: dog

Merge into all documents

Currently yq only has multi-document support for the first document being merged into. The remaining yaml files will have their first document selected.

Given a data1.yaml file of:

something: else
---
a: simple
b: cat

and data3.yaml file of:

b: dog

then

yq m -x -d'*' data1.yaml data3.yaml

will output:

b: dog
something: else
---
a: simple
b: dog