How to use YAML Aliases

Jason Hee
CodeX
Published in
2 min readMay 7, 2021

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Photo by Ferenc Almasi on Unsplash

Have you ever had to copy and paste duplicate content in a YAML file and wondered if it is possible to DRY that up? As it turns out, YAML allows you to repeat nodes via aliases.

YAML Aliases allow you to assign a name to a value or block of data and recall the assigned data by its name in the YAML file. Aliases should work for any file written in YAML.

Simple Example

hello: &hello 'hello'greeting:
audience: 'world'
hello: *hello #greeting.hello has the string value of 'hello'
new_greeting:
audience: 'room'
hello: *hello #new_greeting.hello has the string value of 'hello'

Aliasing blocks of data

Besides string or number values, you can alias a block of data as well:

foo:
bar: &bar
qux: 'quxqux'
baz: 'bazbaz'
greeting:
audience: 'world'
bar: *bar #greeting.bar has the same values as foo.bar.
#So greeting.bar.baz is 'bazbaz'

Modifying a section of an alias

You can copy an alias and modify a section of it by using the merge key (<<:):

bar: &bar
qux: 'quxqux'
baz: 'bazbaz'
greeting:
audience: 'world'
bar:
<<

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