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These follow the same principle as jsondecode and jsonencode, but use YAML instead of JSON. YAML has a much more complex information model than JSON, so we can only support a subset of it during decoding, but hopefully the subset supported here is a useful one. Because there are many different ways to _generate_ YAML, the yamlencode function is forced to make some decisions, and those decisions are likely to affect compatibility with other real-world YAML parsers. Although the format here is intended to be generic and compatible, we may find that there are problems with it that'll we'll want to adjust for in a future release, so yamlencode is therefore marked as experimental for now until the underlying library is ready to commit to ongoing byte-for-byte compatibility in serialization. The main use-case here is met by yamldecode, which will allow reading in files written in YAML format by humans for use in Terraform modules, in situations where a higher-level input format than direct Terraform language declarations is helpful.
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| layout | page_title | sidebar_current | description |
|---|---|---|---|
| functions | yamlencode - Functions - Configuration Language | docs-funcs-encoding-yamlencode | The yamlencode function encodes a given value as a YAML string. |
yamlencode Function
-> Note: This page is about Terraform 0.12 and later. For Terraform 0.11 and earlier, see 0.11 Configuration Language: Interpolation Syntax.
yamlencode encodes a given value to a string using
YAML 1.2 block syntax.
~> Warning: This function is currently experimental and its exact
result format may change in future versions of Terraform, based on feedback.
Do not use yamldecode to construct a value for any resource argument where
changes to the result would be disruptive. To get a consistent string
representation of a value use jsonencode instead; its
results are also valid YAML because YAML is a JSON superset.
This function maps Terraform language values to YAML tags in the following way:
| Terraform type | YAML 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 Terraform language
types, passing the yamlencode result to yamldecode will not produce an
identical value, but the Terraform language automatic type conversion rules
mean that this is rarely a problem in practice.
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.
Related Functions
jsonencodeis a similar operation using JSON instead of YAML.yamldecodeperforms the opposite operation, decoding a YAML string to obtain its represented value.