Amazon CloudWatch Logs

{'startFromHead': 'boolean'}

Lists log events from the specified log group. You can list all the log events or filter the results using one or more of the following:

• A filter pattern

• A time range

• The log stream name, or a log stream name prefix that matches multiple log streams

You must have the logs:FilterLogEvents permission to perform this operation.

You can specify the log group to search by using either logGroupIdentifier or logGroupName. You must include one of these two parameters, but you can't include both.

FilterLogEvents is a paginated operation. Each page returned can contain up to 1 MB of log events or up to 10,000 log events. A returned page might only be partially full, or even empty. For example, if the result of a query would return 15,000 log events, the first page isn't guaranteed to have 10,000 log events even if they all fit into 1 MB.

Partially full or empty pages don't necessarily mean that pagination is finished. If the results include a nextToken, there might be more log events available. You can return these additional log events by providing the nextToken in a subsequent FilterLogEvents operation. If the results don't include a nextToken, then pagination is finished.

Specifying the limit parameter only guarantees that a single page doesn't return more log events than the specified limit, but it might return fewer events than the limit. This is the expected API behavior.

The returned log events are sorted by event timestamp, the timestamp when the event was ingested by CloudWatch Logs, and the ID of the PutLogEvents request. By default, the events are returned in ascending timestamp order (oldest first). To return events in descending timestamp order (newest first), set the startFromHead parameter to false.

If you are using CloudWatch cross-account observability, you can use this operation in a monitoring account and view data from the linked source accounts. For more information, see CloudWatch cross-account observability.

See also: AWS API Documentation

Request Syntax

client.filter_log_events(
    logGroupName='string',
    logGroupIdentifier='string',
    logStreamNames=[
        'string',
    ],
    logStreamNamePrefix='string',
    startTime=123,
    endTime=123,
    filterPattern='string',
    nextToken='string',
    limit=123,
    startFromHead=True|False,
    interleaved=True|False,
    unmask=True|False
)

type logGroupName:

string

param logGroupName:

The name of the log group to search.

type logGroupIdentifier:

string

param logGroupIdentifier:

Specify either the name or ARN of the log group to view log events from. If the log group is in a source account and you are using a monitoring account, you must use the log group ARN.

type logStreamNames:

list

param logStreamNames:

Filters the results to only logs from the log streams in this list.

If you specify a value for both logStreamNames and logStreamNamePrefix, the action returns an InvalidParameterException error.

• (string) --

type logStreamNamePrefix:

string

param logStreamNamePrefix:

Filters the results to include only events from log streams that have names starting with this prefix.

If you specify a value for both logStreamNamePrefix and logStreamNames, the action returns an InvalidParameterException error.

type startTime:

integer

param startTime:

The start of the time range, expressed as the number of milliseconds after Jan 1, 1970 00:00:00 UTC. Events with a timestamp before this time are not returned.

type endTime:

integer

param endTime:

The end of the time range, expressed as the number of milliseconds after Jan 1, 1970 00:00:00 UTC. Events with a timestamp later than this time are not returned.

type filterPattern:

string

param filterPattern:

The filter pattern to use. For more information, see Filter and Pattern Syntax.

If not provided, all the events are matched.

type nextToken:

string

param nextToken:

The token for the next set of events to return. (You received this token from a previous call.)

type limit:

integer

param limit:

The maximum number of events to return. The default is 10,000 events.

type startFromHead:

boolean

param startFromHead:

If the value is true, the earliest log events are returned first. If the value is false, the latest log events are returned first. The default value is true.

The startFromHead parameter sets the sort direction on the first request. On subsequent requests, the nextToken determines the sort direction. To continue paginating in the same direction, provide the returned nextToken. If you provide both nextToken and startFromHead, the direction of the nextToken is used.

type interleaved:

boolean

param interleaved:

If the value is true, the operation attempts to provide responses that contain events from multiple log streams within the log group, interleaved in a single response. If the value is false, all the matched log events in the first log stream are searched first, then those in the next log stream, and so on.

Important As of June 17, 2019, this parameter is ignored and the value is assumed to be true. The response from this operation always interleaves events from multiple log streams within a log group.

type unmask:

boolean

param unmask:

Specify true to display the log event fields with all sensitive data unmasked and visible. The default is false.

To use this operation with this parameter, you must be signed into an account with the logs:Unmask permission.

rtype:

dict

returns:

Response Syntax

{
    'events': [
        {
            'logStreamName': 'string',
            'timestamp': 123,
            'message': 'string',
            'ingestionTime': 123,
            'eventId': 'string'
        },
    ],
    'searchedLogStreams': [
        {
            'logStreamName': 'string',
            'searchedCompletely': True|False
        },
    ],
    'nextToken': 'string'
}

Response Structure

• (dict) --

  • events (list) --

    The matched events.

    • (dict) --

      Represents a matched event.

      • logStreamName (string) --

        The name of the log stream to which this event belongs.

      • timestamp (integer) --

        The time the event occurred, expressed as the number of milliseconds after Jan 1, 1970 00:00:00 UTC.

      • message (string) --

        The data contained in the log event.

      • ingestionTime (integer) --

        The time the event was ingested, expressed as the number of milliseconds after Jan 1, 1970 00:00:00 UTC.

      • eventId (string) --

        The ID of the event.

  • searchedLogStreams (list) --

    Important As of May 15, 2020, this parameter is no longer supported. This parameter returns an empty list.

    Indicates which log streams have been searched and whether each has been searched completely.

    • (dict) --

      Represents the search status of a log stream.

      • logStreamName (string) --

        The name of the log stream.

      • searchedCompletely (boolean) --

        Indicates whether all the events in this log stream were searched.

  • nextToken (string) --

    The token for the next set of items in the sorting direction specified by the startFromHead parameter in the first request. The token expires after 24 hours.

    If the results don't include a nextToken, then pagination is finished.