for event in payload['logEvents']:
  # ...
  cw_client.put_metric_data(...)

[
    {
        'MetricName': 'SomeMetric1',
        'Dimensions': [
            {
                'Name': 'Dimension1Name',
                'Value': 'Dimension1Value'
            },
            # Up to other 9 dimensions here ...
        ],
        'Unit': 'Count',
        'Values': [217, 220, 221], # Up to 150 items here ...
        'Timestamp': 1624290910000
    },
    # Up to other 19 metric items here ...
]

import boto3
import gzip

endpoint_url = "http://localhost:8000/"

cw_client = boto3.client('cloudwatch', endpoint_url=endpoint_url, use_ssl=False)

cw_client.put_metric_data(
    MetricData = [
        {
            'MetricName': 'TEST_BOTO',
            'Dimensions': [
                {
                    'Name': 'APP_VERSION',
                    'Value': '1.0'
                },
            ],
            'Unit': 'None',
            'Value': 17
        },
    ],
    Namespace='BotoTest'
)

import boto3

lambda_client = boto3.client('lambda')

# our event handler
def add_xtrace_header(request, **kwargs):
    request.headers.add_header('x-trace-id', 'trace-trace')

# get the event system for the lambda_client
event_system = lambda_client.meta.events

# attach an event handler to the client for 
event_system.register('before-sign.lambda.Invoke', add_xtrace_header)

# invoke a lambda function
lambda_client.invoke(FunctionName='my-function')

import boto3
import gzip

cw_client = boto3.client('cloudwatch')
event_system = cw_client.meta.events

# Gzip handler
def gzip_request_body(request, **kwargs):
    request.headers.add_header('Content-Encoding', 'gzip')
    gzipped_body = gzip.compress(request.body)
    request.data = gzipped_body

# registers the custom handler
event_system.register('before-sign.cloudwatch.PutMetricData', 
                      gzip_request_body)

cw_client.put_metric_data(...)