Monitoring AWS Lambda functions with Datadog Example

datadog_lambda.py

"""Send metrics over stdout for datadog lambda monitoring.

Monitoring details:
    https://www.datadoghq.com/blog/monitoring-lambda-functions-datadog/

"""
import time
from copy import copy


CONFIG = {
    'tags': {},
    'required_tags': ['dept', 'env', 'app'],
    'metrics_types': ['count', 'gauge']
}


def tag_str(tags):
    """Converts a dictionary to a datadog tag string.

    Args:
        tags (dict): Tags to convert

    Returns:
        str: Datadog tags

    """
    return ','.join(["{}:{}".format(key, val) for key, val in tags.items()])


def post(metric_value, metric_type, metric_name, **kwargs):
    """Post a given metric

    Args:
        metric_value (str): Value of the metric that can be converted to a str
        metric_type (str): Datadog metric type to post (count, or gauge)
        metric_name (str): Name of the metric
        kwargs (str): Keyword arguments to tag metric with

    """
    metric_ts = int(time.time())

    post_tags = copy(CONFIG['tags'])
    post_tags.update(kwargs)

    print('MONITORING|{epoch_ts}|{m_value}|{m_type}|{m_name}|#{tags}'.format(
        epoch_ts=metric_ts,
        m_value=metric_value,
        m_type=metric_type,
        m_name=metric_name,
        tags=tag_str(post_tags)
    ))


def gauge(metric_value, metric_name, **kwargs):
    """Post a given gauge metric

    Args:
        metric_value (str): Value of the metric that can be converted to a str
        metric_name (str): Name of the metric
        kwargs (str): Keyword arguments to tag metric with

    """
    return post(metric_value, 'gauge', metric_name, **kwargs)


def count(metric_value, metric_name, **kwargs):
    """Post a given count metric

    Args:
        metric_value (str): Value of the metric that can be converted to a str
        metric_name (str): Name of the metric
        kwargs (str): Keyword arguments to tag metric with

    """
    return post(metric_value, 'count', metric_name, **kwargs)


def set_constant_tags(tags):
    """Set constant tags.

    Sets tags that will be sent with all metrics posted.

    Args:
        tags (dict): Dictiony of tags

    """
    if not all(tag in tags for tag in CONFIG['required_tags']):
        raise ValueError("Not all required tags have been set")
    CONFIG['tags'] = copy(tags)


def _example():
    set_constant_tags({
        'dept': 'dmds',
        'env': 'test',
        'app': 'simple_example',
        'bonus': 'new_tag'
    })
    count(1, 'example.counter')
    gauge(1.3, 'example.gauge')

    count(1, 'example.counter', server_node='fancy')
    count(1, 'example.counter', server_node='pants')


if __name__ == '__main__':
    _example()