startLiveTail method

Future<StartLiveTailResponse> startLiveTail({ required List<String> logGroupIdentifiers, String? logEventFilterPattern, List<String>? logStreamNamePrefixes, List<String>? logStreamNames, })

Starts a Live Tail streaming session for one or more log groups. A Live Tail session returns a stream of log events that have been recently ingested in the log groups. For more information, see Use Live Tail to view logs in near real time.

The response to this operation is a response stream, over which the server sends live log events and the client receives them.

The following objects are sent over the stream:

• A single LiveTailSessionStart object is sent at the start of the session.
• Every second, a LiveTailSessionUpdate object is sent. Each of these objects contains an array of the actual log events.

  If no new log events were ingested in the past second, the LiveTailSessionUpdate object will contain an empty array.

  The array of log events contained in a LiveTailSessionUpdate can include as many as 500 log events. If the number of log events matching the request exceeds 500 per second, the log events are sampled down to 500 log events to be included in each LiveTailSessionUpdate object.

  If your client consumes the log events slower than the server produces them, CloudWatch Logs buffers up to 10 LiveTailSessionUpdate events or 5000 log events, after which it starts dropping the oldest events.

• A SessionStreamingException object is returned if an unknown error occurs on the server side.
• A SessionTimeoutException object is returned when the session times out, after it has been kept open for three hours.

For examples of using an SDK to start a Live Tail session, see Start a Live Tail session using an Amazon Web Services SDK.

May throw AccessDeniedException. May throw InvalidOperationException. May throw InvalidParameterException. May throw LimitExceededException. May throw ResourceNotFoundException.

Parameter logGroupIdentifiers : An array where each item in the array is a log group to include in the Live Tail session.

Specify each log group by its ARN.

If you specify an ARN, the ARN can't end with an asterisk (*).

Parameter logEventFilterPattern : An optional pattern to use to filter the results to include only log events that match the pattern. For example, a filter pattern of error 404 causes only log events that include both error and 404 to be included in the Live Tail stream.

Regular expression filter patterns are supported.

For more information about filter pattern syntax, see Filter and Pattern Syntax.

Parameter logStreamNamePrefixes : If you specify this parameter, then only log events in the log streams that have names that start with the prefixes that you specify here are included in the Live Tail session.

If you specify this field, you can't also specify the logStreamNames field.

Parameter logStreamNames : If you specify this parameter, then only log events in the log streams that you specify here are included in the Live Tail session.

If you specify this field, you can't also specify the logStreamNamePrefixes field.

Implementation

Future<StartLiveTailResponse> startLiveTail({
  required List<String> logGroupIdentifiers,
  String? logEventFilterPattern,
  List<String>? logStreamNamePrefixes,
  List<String>? logStreamNames,
}) async {
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'Logs_20140328.StartLiveTail'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'logGroupIdentifiers': logGroupIdentifiers,
      if (logEventFilterPattern != null)
        'logEventFilterPattern': logEventFilterPattern,
      if (logStreamNamePrefixes != null)
        'logStreamNamePrefixes': logStreamNamePrefixes,
      if (logStreamNames != null) 'logStreamNames': logStreamNames,
    },

    hostPrefix: 'stream-',
  );

  return StartLiveTailResponse.fromJson(jsonResponse.body);
}