Python/Boto - Writing to AWS CloudWatch Logs without sequence token

I am trying to send logs to AWS CloudWatch Logs using Python and Boto framework. I am doing this:

res=logs.put_log_events("FOO", "BAR",
     [{'timestamp':int(round(time.time() * 1000)),
       'message':time.strftime("%m/%d/%Y %H:%M:%S")+' Scheduled  monitoring check' }], 
     sequence_token=None)

I get an error each time I run:

boto.logs.exceptions.InvalidSequenceTokenException: InvalidSequenceTokenException: 400 Bad Request
{u'message': u'The given sequenceToken is invalid. The next expected sequenceToken is: 49540113336360065754596906019042392283494234157161146226', u'expectedSequenceToken': u'49540113336360065754596906019042392283494234157161146226', u'__type': u'InvalidSequenceTokenException'}

It is somewhat impractical for me to store that token. It makes no sense, why can't I just append to the log stream ?

How can I get around this ?

Solution

You can get around it by first looking up the uploadSequenceToken via describe_log_streams():

Essentially, the process is that you use the logStreamNamePrefix to specifically identify the logstream that you want to append to. Then parse the uploadSequenceToken out of the response.

Response Syntax
 {
     'logStreams': [
         {
             'logStreamName': 'string',
             'creationTime': 123,
             'firstEventTimestamp': 123,
             'lastEventTimestamp': 123,
             'lastIngestionTime': 123,
             'uploadSequenceToken': 'string',
             'arn': 'string',
             'storedBytes': 123
         },
     ],
     'nextToken': 'string'
 }
Returns all the log streams that are associated with the specified log group. The list returned in the response is ASCII-sorted by log stream name.

By default, this operation returns up to 50 log streams. If there are more log streams to list, the response would contain a nextToken value in the response body. You can also limit the number of log streams returned in the response by specifying the limit parameter in the request. This operation has a limit of five transactions per second, after which transactions are throttled.

Request Syntax
response = client.describe_log_streams(
    logGroupName='string',
    logStreamNamePrefix='string',
    orderBy='LogStreamName'|'LastEventTime',
    descending=True|False,
    nextToken='string',
    limit=123
)