cloudposse/atmos v1.111.0 on GitHub

Introduce Atmos YAML functions @aknysh (#810)

what

Introduce Atmos YAML functions
Update docs

why

Atmos YAML Functions are a crucial part of Atmos stack manifests. They allow you to manipulate data and perform operations on the data to customize the stack configurations.

Atmos YAML functions are based on YAML Explicit typing and user-defined Explicit Tags (local data types). Explicit tags are denoted by the exclamation point ("!") symbol. Atmos detects the tags in the stack manifests and executes the corresponding functions.

NOTE: YAML data types can be divided into three categories: core, defined, and user-defined. Core are ones expected to exist in any parser (e.g. floats, ints, strings, lists, maps). Many more advanced data types, such as binary data, are defined in the YAML specification but not supported in all implementations. Finally, YAML defines a way to extend the data type definitions locally to accommodate user-defined classes, structures, primitives, and functions.

Atmos YAML functions

The !template YAML function can be used to handle template outputs containing maps or lists returned from the atmos.Component template function
The !exec YAML function is used to execute shell scripts and assign the results to the sections in Atmos stack manifests
The !terraform.output YAML function is used to read the outputs (remote state) of components directly in Atmos stack manifests

NOTE: You can use Atmos Stack Manifest Templating and Atmos YAML functions in the same stack configurations at the same time. Atmos processes the templates first, and then executes the YAML functions, allowing you to provide the parameters to the YAML functions dynamically.

Examples

components:
  terraform:
    component2:
      vars:
        # Handle the output of type list from the `atmos.Component` template function
        test_1: !template '{{ toJson (atmos.Component "component1" "plat-ue2-dev").outputs.test_list }}'

        # Handle the output of type map from the `atmos.Component` template function
        test_2: !template '{{ toJson (atmos.Component "component1" .stack).outputs.test_map }}'

        # Execute the shell script and assign the result to the `test_3` variable
        test_3: !exec echo 42

        # Execute the shell script to get the `test_label_id` output from the `component1` component in the stack `plat-ue2-dev`
        test_4: !exec atmos terraform output component1 -s plat-ue2-dev --skip-init -- -json test_label_id

        # Execute the shell script to get the `test_map` output from the `component1` component in the current stack
        test_5: !exec atmos terraform output component1 -s {{ .stack }} --skip-init -- -json test_map

        # Execute the shell script to get the `test_list` output from the `component1` component in the current stack
        test_6: !exec atmos terraform output component1 -s {{ .stack }} --skip-init -- -json test_list

        # Get the `test_label_id` output of type string from the `component1` component in the stack `plat-ue2-dev`
        test_7: !terraform.output component1 plat-ue2-dev test_label_id

        # Get the `test_label_id` output of type string from the `component1` component in the current stack
        test_8: !terraform.output component1 {{ .stack }} test_label_id

        # Get the `test_list` output of type list from the `component1` component in the current stack
        test_9: !terraform.output component1 {{ .stack }} test_list

        # Get the `test_map` output of type map from the `component1` component in the current stack
        test_10: !terraform.output component1 {{ .stack }} test_map