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# Creating Alarms in Amazon CloudWatch
![\[JavaScript code example that applies to Node.js execution\]](http://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/images/nodeicon.png)
**This Node.js code example shows:**
+ How to retrieve basic information about your CloudWatch alarms.
+ How to 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, a series of Node.js modules are used to create alarms in CloudWatch. The Node.js modules use the SDK for JavaScript to create alarms using these methods of the `AWS.CloudWatch` client class:
+ [https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#describeAlarms-property](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#describeAlarms-property)
+ [https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#putMetricAlarm-property](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#putMetricAlarm-property)
+ [https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#deleteAlarms-property](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudWatch.html#deleteAlarms-property)
For more information about CloudWatch alarms, see [Creating Amazon CloudWatch Alarms](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/AlarmThatSendsEmail.html) in the *Amazon CloudWatch User Guide*.
## Prerequisite Tasks
To set up and run this example, you must first complete these tasks:
+ Install Node.js. For more information about installing Node.js, see the [Node.js website](https://nodejs.org).
+ Create a shared configurations file with your user credentials. For more information about providing a shared credentials file, see [Loading Credentials in Node.js from the Shared Credentials File](loading-node-credentials-shared.md).
## Describing Alarms
Create a Node.js module with the file name `cw_describealarms.js`. Be sure to configure the SDK as previously shown. To access CloudWatch, create an `AWS.CloudWatch` service object. Create a JSON object to hold the parameters for retrieving alarm descriptions, limiting the alarms returned to those with a state of `INSUFFICIENT_DATA`. Then call the `describeAlarms` method of the `AWS.CloudWatch` service object.
```
// Load the AWS SDK for Node.js
var AWS = require("aws-sdk");
// Set the region
AWS.config.update({ region: "REGION" });
// Create CloudWatch service object
var cw = new AWS.CloudWatch({ apiVersion: "2010-08-01" });
cw.describeAlarms({ StateValue: "INSUFFICIENT_DATA" }, function (err, data) {
if (err) {
console.log("Error", err);
} else {
// List the names of all current alarms in the console
data.MetricAlarms.forEach(function (item, index, array) {
console.log(item.AlarmName);
});
}
});
```
To run the example, type the following at the command line.
```
node cw_describealarms.js
```
This sample code can be found [here on GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/javascript/example_code/cloudwatch/cw_describealarms.js).
## Creating an Alarm for a CloudWatch Metric
Create a Node.js module with the file name `cw_putmetricalarm.js`. Be sure to configure the SDK as previously shown. To access CloudWatch, create an `AWS.CloudWatch` service object. Create a JSON object for the parameters needed to create an alarm based on a metric, in this case the CPU utilization of an Amazon EC2 instance. The remaining parameters are set so the alarm triggers when the metric exceeds a threshold of 70 percent. Then call the `describeAlarms` method of the `AWS.CloudWatch` service object.
```
// Load the AWS SDK for Node.js
var AWS = require("aws-sdk");
// Set the region
AWS.config.update({ region: "REGION" });
// Create CloudWatch service object
var cw = new AWS.CloudWatch({ apiVersion: "2010-08-01" });
var params = {
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: "Percent",
};
cw.putMetricAlarm(params, function (err, data) {
if (err) {
console.log("Error", err);
} else {
console.log("Success", data);
}
});
```
To run the example, type the following at the command line.
```
node cw_putmetricalarm.js
```
This sample code can be found [here on GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/javascript/example_code/cloudwatch/cw_putmetricalarm.js).
## Deleting an Alarm
Create a Node.js module with the file name `cw_deletealarms.js`. Be sure to configure the SDK as previously shown. To access CloudWatch, create an `AWS.CloudWatch` service object. Create a JSON object to hold the names of the alarms you want to delete. Then call the `deleteAlarms` method of the `AWS.CloudWatch` service object.
```
// Load the AWS SDK for Node.js
var AWS = require("aws-sdk");
// Set the region
AWS.config.update({ region: "REGION" });
// Create CloudWatch service object
var cw = new AWS.CloudWatch({ apiVersion: "2010-08-01" });
var params = {
AlarmNames: ["Web_Server_CPU_Utilization"],
};
cw.deleteAlarms(params, function (err, data) {
if (err) {
console.log("Error", err);
} else {
console.log("Success", data);
}
});
```
To run the example, type the following at the command line.
```
node cw_deletealarms.js
```
This sample code can be found [here on GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/javascript/example_code/cloudwatch/cw_deletealarms.js).