attune/docs/parameters/dotenv-parameter-format.md

DOTENV Parameter Format

Overview

The DOTENV parameter format is used to pass action parameters securely via stdin in a shell-compatible format. This format is particularly useful for shell scripts that need to parse parameters without relying on external tools like jq.

Format Specification

Basic Format

Parameters are formatted as key='value' pairs, one per line:

url='https://example.com'
method='GET'
timeout='30'
verify_ssl='true'

Nested Object Flattening

Nested JSON objects are automatically flattened using dot notation. This allows shell scripts to easily parse complex parameter structures.

Input JSON:

{
  "url": "https://example.com",
  "headers": {
    "Content-Type": "application/json",
    "Authorization": "Bearer token123"
  },
  "query_params": {
    "page": "1",
    "size": "10"
  }
}

Output DOTENV:

headers.Authorization='Bearer token123'
headers.Content-Type='application/json'
query_params.page='1'
query_params.size='10'
url='https://example.com'

Empty Objects

Empty objects ({}) are omitted from the output entirely. They do not produce any dotenv entries.

Input:

{
  "url": "https://example.com",
  "headers": {},
  "query_params": {}
}

Output:

url='https://example.com'

Arrays

Arrays are serialized as JSON strings:

Input:

{
  "tags": ["web", "api", "production"]
}

Output:

tags='["web","api","production"]'

Special Characters

Single quotes in values are escaped using the shell-safe '\'' pattern:

Input:

{
  "message": "It's working!"
}

Output:

message='It'\''s working!'

Shell Script Parsing

Basic Parameter Parsing

#!/bin/sh

# Read DOTENV-formatted parameters from stdin
while IFS= read -r line; do
    case "$line" in
        *"---ATTUNE_PARAMS_END---"*) break ;;
    esac
    [ -z "$line" ] && continue

    key="${line%%=*}"
    value="${line#*=}"

    # Remove quotes
    case "$value" in
        \"*\") value="${value#\"}"; value="${value%\"}" ;;
        \'*\') value="${value#\'}"; value="${value%\'}" ;;
    esac

    # Process parameters
    case "$key" in
        url) url="$value" ;;
        method) method="$value" ;;
        timeout) timeout="$value" ;;
    esac
done

Parsing Nested Objects

For flattened nested objects, use pattern matching on the key prefix:

# Create temporary files for nested data
headers_file=$(mktemp)
query_params_file=$(mktemp)

while IFS= read -r line; do
    case "$line" in
        *"---ATTUNE_PARAMS_END---"*) break ;;
    esac
    [ -z "$line" ] && continue

    key="${line%%=*}"
    value="${line#*=}"

    # Remove quotes
    case "$value" in
        \'*\') value="${value#\'}"; value="${value%\'}" ;;
    esac

    # Process parameters
    case "$key" in
        url) url="$value" ;;
        method) method="$value" ;;
        headers.*)
            # Extract nested key (e.g., "Content-Type" from "headers.Content-Type")
            nested_key="${key#headers.}"
            printf '%s: %s\n' "$nested_key" "$value" >> "$headers_file"
            ;;
        query_params.*)
            nested_key="${key#query_params.}"
            printf '%s=%s\n' "$nested_key" "$value" >> "$query_params_file"
            ;;
    esac
done

# Use the parsed data
if [ -s "$headers_file" ]; then
    while IFS= read -r header; do
        curl_args="$curl_args -H '$header'"
    done < "$headers_file"
fi

Configuration

Action YAML Configuration

Specify DOTENV format in your action YAML:

ref: mypack.myaction
entry_point: myaction.sh
parameter_delivery: stdin
parameter_format: dotenv  # Use dotenv format
output_format: json

Supported Formats

• dotenv - Shell-friendly key='value' format with nested object flattening
• json - Standard JSON format
• yaml - YAML format

Supported Delivery Methods

• stdin - Parameters passed via stdin (recommended for security)
• file - Parameters written to a temporary file

Security Considerations

Why DOTENV + STDIN?

This combination provides several security benefits:

1. No process list exposure: Parameters don't appear in ps aux output
2. No shell escaping issues: Values are properly quoted
3. Secret protection: Sensitive values passed via stdin, not environment variables
4. No external dependencies: Pure POSIX shell parsing without jq or other tools

Secret Handling

Secrets are passed separately via stdin after parameters. They are never included in environment variables or parameter files.

# Parameters are sent first
url='https://api.example.com'
---ATTUNE_PARAMS_END---
# Then secrets (as JSON)
{"api_key":"secret123","password":"hunter2"}

Examples

Example 1: HTTP Request Action

Action Configuration:

ref: core.http_request
parameter_delivery: stdin
parameter_format: dotenv

Execution Parameters:

{
  "url": "https://api.example.com/users",
  "method": "POST",
  "headers": {
    "Content-Type": "application/json",
    "User-Agent": "Attune/1.0"
  },
  "query_params": {
    "page": "1",
    "limit": "10"
  }
}

Stdin Input:

headers.Content-Type='application/json'
headers.User-Agent='Attune/1.0'
method='POST'
query_params.limit='10'
query_params.page='1'
url='https://api.example.com/users'
---ATTUNE_PARAMS_END---

Example 2: Simple Shell Action

Action Configuration:

ref: mypack.greet
parameter_delivery: stdin
parameter_format: dotenv

Execution Parameters:

{
  "name": "Alice",
  "greeting": "Hello"
}

Stdin Input:

greeting='Hello'
name='Alice'
---ATTUNE_PARAMS_END---

Troubleshooting

Issue: Parameters Not Received

Symptom: Action receives empty or incorrect parameter values.

Solution: Ensure you're reading until the ---ATTUNE_PARAMS_END--- delimiter:

while IFS= read -r line; do
    case "$line" in
        *"---ATTUNE_PARAMS_END---"*) break ;;  # Important!
    esac
    # ... parse line
done

Issue: Nested Objects Not Parsed

Symptom: Headers or query params not being set correctly.

Solution: Use pattern matching to detect dotted keys:

case "$key" in
    headers.*)
        nested_key="${key#headers.}"
        # Process nested key
        ;;
esac

Issue: Special Characters Corrupted

Symptom: Values with single quotes are malformed.

Solution: The worker automatically escapes single quotes using '\''. Make sure to remove quotes correctly:

# Remove quotes (handles escaped quotes correctly)
case "$value" in
    \'*\') value="${value#\'}"; value="${value%\'}" ;;
esac

Best Practices

1. Always read until delimiter: Don't stop reading stdin early
2. Handle empty objects: Check if files are empty before processing
3. Use temporary files: For nested objects, write to temp files for easier processing
4. Validate required parameters: Check that required values are present
5. Clean up temp files: Use trap to ensure cleanup on exit

#!/bin/sh
set -e

# Setup cleanup
headers_file=$(mktemp)
trap "rm -f $headers_file" EXIT

# Parse parameters...

Implementation Details

The parameter flattening is implemented in crates/worker/src/runtime/parameter_passing.rs:

• Nested objects are recursively flattened with dot notation
• Empty objects produce no output entries
• Arrays are JSON-serialized as strings
• Output is sorted alphabetically for consistency
• Single quotes are escaped using shell-safe '\'' pattern

See Also

• Action Parameter Schema
• Secrets Management
• Shell Runtime