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yamlencode Function

yamlencode encodes a given value to a string using YAML 1.2 block syntax.

This function maps OpenTF language values to YAML tags in the following way:

OpenTF typeYAML type
string!!str
number!!float or !!int
bool!!bool
list(...)!!seq
set(...)!!seq
tuple(...)!!seq
map(...)!!map
object(...)!!map
Null value!!null

yamlencode uses the implied syntaxes for all of the above types, so it does not generate explicit YAML tags.

Because the YAML format cannot fully represent all of the OpenTF language types, passing the yamlencode result to yamldecode will not produce an identical value, but the OpenTF language automatic type conversion rules mean that this is rarely a problem in practice.

YAML is a superset of JSON, and so where possible we recommend generating JSON using jsonencode instead, even if a remote system supports YAML. JSON syntax is equivalent to flow-style YAML and OpenTF can present detailed structural change information for JSON values in plans, whereas OpenTF will treat block-style YAML just as a normal multi-line string. However, generating YAML may improve readability if the resulting value will be directly read or modified in the remote system by humans.

Examples​

> yamlencode({"a":"b", "c":"d"})
"a": "b"
"c": "d"

> yamlencode({"foo":[1, 2, 3], "bar": "baz"})
"bar": "baz"
"foo":
- 1
- 2
- 3

> yamlencode({"foo":[1, {"a":"b","c":"d"}, 3], "bar": "baz"})
"bar": "baz"
"foo":
- 1
- "a": "b"
  "c": "d"
- 3

yamlencode always uses YAML's "block style" for mappings and sequences, unless the mapping or sequence is empty. To generate flow-style YAML, use jsonencode instead: YAML flow-style is a superset of JSON syntax.

  • jsonencode is a similar operation using JSON instead of YAML.
  • yamldecode performs the opposite operation, decoding a YAML string to obtain its represented value.