Packer
yamlencode Function
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 Packer, 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 Packer language values to YAML tags in the following way:
| Packer 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 syntax for all of the above types, so it does
not generate explicit YAML tags.
Because the YAML format cannot fully represent all of the Packer language
types, passing the yamlencode result to yamldecode will not produce an
identical value, but the Packer 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.