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Overview

The scripting node runs code the user provides in JavaScript or Python. The Worker resolves the node from the database, invokes the matching Lambda executor, persists result and console on the node row, and returns the same payload to the workflow. The Temporal activity scriptingActivity delegates to ScriptingService.process.

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When it runs

scriptingActivity is invoked from the processSingleNode workflow when the node type is scripting (NodeType.SCRIPTING).

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Activity signature

async scriptingActivity({
  nodeId: string,
  sessionId: string,
  userId: string,
}): Promise<ScriptingResponse>
ScriptingResponse: 
{
  result?: unknown;   // script “output”
  console?: unknown[]; // collected logs
}

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End-to-end flow

  1. Load flows_nodes by nodeId and read data (language, script source, variables).
  2. Choose the Lambda function from data.language and env vars (see below).
  3. Build the script string: prefer merged scriptData[] rows (text joined by newlines); if empty, use data.script.
  4. Invoke Lambda with { script, variables }.
  5. On success, merge result and console into data and UPDATE flows_nodes.
  6. Return { result, console } to the workflow.
Lambda errors (missing function, runtime errors, timeouts) surface as thrown errors in the Worker.

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Outputs

ConceptMeaning
OutputStored in result. How it is set depends on the runtime (see Executors).
ConsoleStored in console: every line produced by the sandbox console API (log, warn, error), including [ERROR] / [WARN] prefixes where applicable.

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Node data fields (Worker expectations)

FieldRole
languageJavaScript or Python (see Language enum in the Worker). Selects which Lambda to call.
scriptFallback script string when scriptData is empty or has no usable text.
scriptDataOptional array of rows; each row’s text is concatenated with newlines and used as the script when non-empty.
variablesArray of { name, value } entries for substitution and (Python) injection (see Variables).
After execution, data is updated with result and console from Lambda.

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Variables

Both executors:
  1. Build a map of variable name → string value.
  2. Replace every occurrence of {{name}} in the script with that string (regex / global replace).
Python also injects assignments at the top of the wrapped file so each name is available as a Python variable (values JSON-serialized for literals). JavaScript also spreads variablesMap onto the VM sandbox so names are available as identifiers in addition to {{name}} placeholders.

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Executors

Execution happens in AWS Lambda, not inside the Worker process.

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Python (py-scripting-node)

  • Timeout: 30 seconds (subprocess).
  • API: console.log, console.error, console.warn; setResult(value) sets the structured output result.
  • Output: The wrapper prints a JSON line with { result, console }. If the process exits non-zero, the Lambda returns an error string (stderr).
  • Placeholders {{varName}} are applied after the variable map is built.

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JavaScript (js-scripting-node)

  • Timeout: 30 seconds (vm.runInContext).
  • API: console.log, console.error, console.warn; setResult(value) sets result.
  • Output: result is scriptResult if setResult was used; otherwise the last expression value from vm.runInContext when it is not undefined; otherwise null.
  • On uncaught errors, the handler returns error (timeout message or err.message) and may still return partial console logs.

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Environment variables (Worker)

VariablePurpose
LAMBDA_JS_SCRIPTING_NODEName of the JS Lambda (for language === JavaScript).
LAMBDA_PY_SCRIPTING_NODEName of the Python Lambda (for language === Python).
AWS_REGIONAWS region for LambdaClient (default in code: us-east-1).
If language does not match a configured Lambda, ScriptingService throws.

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Local development

When NODE_ENV === 'local', ScriptingModule configures the AWS SDK LambdaClient with explicit credentials from the environment:
  • AWS_ACCESS_KEY_ID
  • AWS_SECRET_ACCESS_KEY
Set these (and region / function names) so local Worker runs can invoke the same Lambdas your AWS account deploys.
Console links to edit Lambda code require an AWS login and are environment-specific. Function names in your account should match LAMBDA_*_SCRIPTING_NODE.