github.com/anth0d/nomad@v0.0.0-20221214183521-ae3a0a2cad06/website/content/docs/job-specification/hcl2/functions/encoding/yamlencode.mdx (about)

     1  ---
     2  layout: docs
     3  page_title: yamlencode - Functions - Configuration Language
     4  description: The yamlencode function encodes a given value as a YAML string.
     5  ---
     6  
     7  # `yamlencode` Function
     8  
     9  `yamlencode` encodes a given value to a string using
    10  [YAML 1.2](https://yaml.org/spec/1.2/spec) block syntax.
    11  
    12  ~> **Warning:** This function is currently **experimental** and its exact
    13  result format may change in future versions of Nomad, based on feedback.
    14  Do not use `yamldecode` to construct a value for any argument where
    15  changes to the result would be disruptive. To get a consistent string
    16  representation of a value use [`jsonencode`](/docs/job-specification/hcl2/functions/encoding/jsonencode) instead; its
    17  results are also valid YAML because YAML is a JSON superset.
    18  
    19  <!--
    20      The condition for removing the above warning is that the underlying
    21      go-cty-yaml folder makes a stable release with a commitment to guarantee
    22      that the representation of particular input will not change without a
    23      major release. It is not making that commitment at the time of writing to
    24      allow for responding to user feedback about its output format, since YAML
    25      is a very flexible format and its initial decisions may prove to be
    26      sub-optimal when generating YAML intended for specific external consumers.
    27  -->
    28  
    29  This function maps
    30  [Nomad language values](/docs/job-specification/hcl2/expressions#types-and-values)
    31  to YAML tags in the following way:
    32  
    33  | Nomad type    | YAML type            |
    34  | ------------- | -------------------- |
    35  | `string`      | `!!str`              |
    36  | `number`      | `!!float` or `!!int` |
    37  | `bool`        | `!!bool`             |
    38  | `list(...)`   | `!!seq`              |
    39  | `set(...)`    | `!!seq`              |
    40  | `tuple(...)`  | `!!seq`              |
    41  | `map(...)`    | `!!map`              |
    42  | `object(...)` | `!!map`              |
    43  | Null value    | `!!null`             |
    44  
    45  `yamlencode` uses the implied syntaxes for all of the above types, so it does
    46  not generate explicit YAML tags.
    47  
    48  Because the YAML format cannot fully represent all of the Nomad language
    49  types, passing the `yamlencode` result to `yamldecode` will not produce an
    50  identical value, but the Nomad language automatic type conversion rules
    51  mean that this is rarely a problem in practice.
    52  
    53  ## Examples
    54  
    55  ```shell-session
    56  > yamlencode({"a":"b", "c":"d"})
    57  "a": "b"
    58  "c": "d"
    59  
    60  > yamlencode({"foo":[1, 2, 3], "bar": "baz"})
    61  "bar": "baz"
    62  "foo":
    63  - 1
    64  - 2
    65  - 3
    66  
    67  > yamlencode({"foo":[1, {"a":"b","c":"d"}, 3], "bar": "baz"})
    68  "bar": "baz"
    69  "foo":
    70  - 1
    71  - "a": "b"
    72    "c": "d"
    73  - 3
    74  ```
    75  
    76  `yamlencode` always uses YAML's "block style" for mappings and sequences, unless
    77  the mapping or sequence is empty. To generate flow-style YAML, use
    78  [`jsonencode`](/docs/job-specification/hcl2/functions/encoding/jsonencode) instead: YAML flow-style is a superset
    79  of JSON syntax.
    80  
    81  ## Related Functions
    82  
    83  - [`jsonencode`](/docs/job-specification/hcl2/functions/encoding/jsonencode) is a similar operation using JSON instead
    84    of YAML.
    85  - [`yamldecode`](/docs/job-specification/hcl2/functions/encoding/yamldecode) performs the opposite operation, _decoding_
    86    a YAML string to obtain its represented value.