Variable Resolution

myna uses a powerful variable substitution system allowing you to parameterize your actions.

Resolution Hierarchy

When a variable like {{MY_VAR}} is encountered, myna looks for its value in the following order (Highest to Lowest Priority):

1. Action [pre]: Variables defined in the action file itself.
2. Collection [pre]: Variables defined in myna.toml.
3. Environment [pre]: Variables defined in environments/<env>.toml.

Example

Action (action.toml):

[pre]
TIMEOUT = 500

Collection (myna.toml):

[pre]
TIMEOUT = 1000
REGION = "us-east-1"

Environment (dev.toml):

[pre]
REGION = "eu-west-1"
STAGE = "dev"

Resulting Values:

• TIMEOUT: 500 (Action overrides Collection)
• REGION: “us-east-1” (Collection overrides Environment)
• STAGE: “dev” (From Environment)

Syntax

Handlebars {{VAR}}

Used inside string values (like payload.data or function_name). This is a direct text replacement.

[payload]
data = """
{
  "id": "{{USER_ID}}"
}
"""

Shell Style ${VAR}

Used mostly when defining variables in TOML tables to reference other variables available at that time/level.

Missing Variables

If a variable is referenced but not found in any of the 3 scopes, myna will:

1. Log a warning to the console.
2. Leave the template string as-is (e.g., {{MISSING_VAR}}).