Send EC2 instance memory usage stats to CloudWatch using boto and IAM Roles

cw-monitor-memusage.py

#!/usr/bin/env python
'''
Send memory usage metrics to Amazon CloudWatch
 
This is intended to run on an Amazon EC2 instance and requires an IAM
role allowing to write CloudWatch metrics. Alternatively, you can create
a boto credentials file and rely on it instead. 

Original idea based on https://github.com/colinbjohnson/aws-missing-tools

(c) 2015 Shahar Evron, all rights reserved; 
You are free to use, modify and redistribute this software in any form
under the conditions described in the LICENSE file included.
'''

import sys
import re
from boto.ec2 import cloudwatch
from boto.utils import get_instance_metadata

def collect_memory_usage():
    meminfo = {}
    pattern = re.compile('([\w\(\)]+):\s*(\d+)(:?\s*(\w+))?')
    with open('/proc/meminfo') as f:
        for line in f:
            match = pattern.match(line)
            if match:
                # For now we don't care about units (match.group(3))
                meminfo[match.group(1)] = float(match.group(2))
    return meminfo

def send_multi_metrics(instance_id, region, metrics, namespace='EC2/Memory',
                        unit='Percent'):
    '''
    Send multiple metrics to CloudWatch
    metrics is expected to be a map of key -> value pairs of metrics
    '''
    cw = cloudwatch.connect_to_region(region)
    cw.put_metric_data(namespace, metrics.keys(), metrics.values(),
                       unit=unit,
                       dimensions={"InstanceId": instance_id})

if __name__ == '__main__':
    metadata = get_instance_metadata()
    instance_id = metadata['instance-id']
    region = metadata['placement']['availability-zone'][0:-1]
    mem_usage = collect_memory_usage()

    mem_free = mem_usage['MemFree'] + mem_usage['Buffers'] + mem_usage['Cached']
    mem_used = mem_usage['MemTotal'] - mem_free
    if mem_usage['SwapTotal'] != 0 :
        swap_used = mem_usage['SwapTotal'] - mem_usage['SwapFree'] - mem_usage['SwapCached']
        swap_percent = swap_used / mem_usage['SwapTotal'] * 100
    else:
        swap_percent = 0

    metrics = {'MemUsage': mem_used / mem_usage['MemTotal'] * 100,
               'SwapUsage': swap_percent }

    send_multi_metrics(instance_id, region, metrics)

LICENSE

Copyright (c) 2015, Shahar Evron
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, 
are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this 
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, 
this list of conditions and the following disclaimer in the documentation and/or 
other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors 
may be used to endorse or promote products derived from this software without 
specific prior written permission.

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