Creating Alarms in Amazon CloudWatch

This Python example shows you how to:

• Get basic information about your CloudWatch alarms
• Create and delete a CloudWatch alarm

The Scenario

An alarm watches a single metric over a time period you specify, and performs one or more actions based on the value of the metric relative to a given threshold over a number of time periods.

In this example, Python code is used to create alarms in CloudWatch. The code uses the uses AWS SDK for Python to create alarms using these methods of the AWS.CloudWatch client class:

• paginate(StateValue='INSUFFICIENT_DATA').
• put_metric_alarm.
• delete_alarms.

For more information about CloudWatch alarms, see Creating Amazon CloudWatch Alarms in the Amazon CloudWatch User Guide.

All the example code for the Amazon Web Services (AWS) SDK for Python is available here on GitHub.

Prerequisite Task

To set up and run this example, you must first configure your AWS credentials, as described in Quickstart.

Describe Alarms

The example below shows how to:

• List metric alarms for insufficient data using paginate(StateValue='INSUFFICIENT_DATA').

For more information about paginators see, Paginators

Example

import boto3

# Create CloudWatch client
cloudwatch = boto3.client('cloudwatch')

# List alarms of insufficient data through the pagination interface
paginator = cloudwatch.get_paginator('describe_alarms')
for response in paginator.paginate(StateValue='INSUFFICIENT_DATA'):
    print(response['MetricAlarms'])

Create an Alarm for a CloudWatch Metric Alarm

Create or update an alarm and associate it with the specified metric alarm. Optionally, this operation can associate one or more Amazon SNS resources with the alarm.

When this operation creates an alarm, the alarm state is immediately set to INSUFFICIENT_DATA. The alarm is evaluated and its state is set appropriately. Any actions associated with the state are then executed.

When you update an existing alarm, its state is left unchanged, but the update completely overwrites the previous configuration of the alarm.

The example below shows how to:

• Create or update a metric alarm using put_metric_alarm.

Example

import boto3

# Create CloudWatch client
cloudwatch = boto3.client('cloudwatch')

# Create alarm
cloudwatch.put_metric_alarm(
    AlarmName='Web_Server_CPU_Utilization',
    ComparisonOperator='GreaterThanThreshold',
    EvaluationPeriods=1,
    MetricName='CPUUtilization',
    Namespace='AWS/EC2',
    Period=60,
    Statistic='Average',
    Threshold=70.0,
    ActionsEnabled=False,
    AlarmDescription='Alarm when server CPU exceeds 70%',
    Dimensions=[
        {
          'Name': 'InstanceId',
          'Value': 'INSTANCE_ID'
        },
    ],
    Unit='Seconds'
)

Delete an Alarm

Delete the specified alarms. In the event of an error, no alarms are deleted.

The example below shows how to:

• Delete a metric alarm using delete_alarms.

Example

import boto3

# Create CloudWatch client
cloudwatch = boto3.client('cloudwatch')

# Delete alarm
cloudwatch.delete_alarms(
  AlarmNames=['Web_Server_CPU_Utilization'],
)