invoke method

Future<InvocationResponse> invoke({ required String functionName, String? clientContext, InvocationType? invocationType, LogType? logType, Uint8List? payload, String? qualifier, })

Invokes a Lambda function. You can invoke a function synchronously (and wait for the response), or asynchronously. To invoke a function asynchronously, set InvocationType to Event.

For synchronous invocation, details about the function response, including errors, are included in the response body and headers. For either invocation type, you can find more information in the execution log and trace.

When an error occurs, your function may be invoked multiple times. Retry behavior varies by error type, client, event source, and invocation type. For example, if you invoke a function asynchronously and it returns an error, Lambda executes the function up to two more times. For more information, see Retry Behavior.

For asynchronous invocation, Lambda adds events to a queue before sending them to your function. If your function does not have enough capacity to keep up with the queue, events may be lost. Occasionally, your function may receive the same event multiple times, even if no error occurs. To retain events that were not processed, configure your function with a dead-letter queue.

The status code in the API response doesn't reflect function errors. Error codes are reserved for errors that prevent your function from executing, such as permissions errors, limit errors, or issues with your function's code and configuration. For example, Lambda returns TooManyRequestsException if executing the function would cause you to exceed a concurrency limit at either the account level (ConcurrentInvocationLimitExceeded) or function level (ReservedFunctionConcurrentInvocationLimitExceeded).

For functions with a long timeout, your client might be disconnected during synchronous invocation while it waits for a response. Configure your HTTP client, SDK, firewall, proxy, or operating system to allow for long connections with timeout or keep-alive settings.

This operation requires permission for the lambda:InvokeFunction action.

May throw ServiceException. May throw ResourceNotFoundException. May throw InvalidRequestContentException. May throw RequestTooLargeException. May throw UnsupportedMediaTypeException. May throw TooManyRequestsException. May throw InvalidParameterValueException. May throw EC2UnexpectedException. May throw SubnetIPAddressLimitReachedException. May throw ENILimitReachedException. May throw EFSMountConnectivityException. May throw EFSMountFailureException. May throw EFSMountTimeoutException. May throw EFSIOException. May throw EC2ThrottledException. May throw EC2AccessDeniedException. May throw InvalidSubnetIDException. May throw InvalidSecurityGroupIDException. May throw InvalidZipFileException. May throw KMSDisabledException. May throw KMSInvalidStateException. May throw KMSAccessDeniedException. May throw KMSNotFoundException. May throw InvalidRuntimeException. May throw ResourceConflictException. May throw ResourceNotReadyException.

Parameter functionName : The name of the Lambda function, version, or alias.

Name formats

• Function name - my-function (name-only), my-function:v1 (with alias).
• Function ARN - arn:aws:lambda:us-west-2:123456789012:function:my-function.
• Partial ARN - 123456789012:function:my-function.

You can append a version number or alias to any of the formats. The length constraint applies only to the full ARN. If you specify only the function name, it is limited to 64 characters in length.

Parameter clientContext : Up to 3583 bytes of base64-encoded data about the invoking client to pass to the function in the context object.

Parameter invocationType : Choose from the following options.

• RequestResponse (default) - Invoke the function synchronously. Keep the connection open until the function returns a response or times out. The API response includes the function response and additional data.
• Event - Invoke the function asynchronously. Send events that fail multiple times to the function's dead-letter queue (if it's configured). The API response only includes a status code.
• DryRun - Validate parameter values and verify that the user or role has permission to invoke the function.

Parameter logType : Set to Tail to include the execution log in the response.

Parameter payload : The JSON that you want to provide to your Lambda function as input.

Parameter qualifier : Specify a version or alias to invoke a published version of the function.

Implementation

Future<InvocationResponse> invoke({
  required String functionName,
  String? clientContext,
  InvocationType? invocationType,
  LogType? logType,
  Uint8List? payload,
  String? qualifier,
}) async {
  ArgumentError.checkNotNull(functionName, 'functionName');
  _s.validateStringLength(
    'functionName',
    functionName,
    1,
    170,
    isRequired: true,
  );
  _s.validateStringLength(
    'qualifier',
    qualifier,
    1,
    128,
  );
  final headers = <String, String>{
    if (clientContext != null)
      'X-Amz-Client-Context': clientContext.toString(),
    if (invocationType != null)
      'X-Amz-Invocation-Type': invocationType.toValue(),
    if (logType != null) 'X-Amz-Log-Type': logType.toValue(),
  };
  final $query = <String, List<String>>{
    if (qualifier != null) 'Qualifier': [qualifier],
  };
  final response = await _protocol.sendRaw(
    payload: payload,
    method: 'POST',
    requestUri:
        '/2015-03-31/functions/${Uri.encodeComponent(functionName)}/invocations',
    queryParams: $query,
    headers: headers,
    exceptionFnMap: _exceptionFns,
  );
  return InvocationResponse(
    payload: await response.stream.toBytes(),
    executedVersion: _s.extractHeaderStringValue(
        response.headers, 'X-Amz-Executed-Version'),
    functionError:
        _s.extractHeaderStringValue(response.headers, 'X-Amz-Function-Error'),
    logResult:
        _s.extractHeaderStringValue(response.headers, 'X-Amz-Log-Result'),
    statusCode: response.statusCode,
  );
}