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Publish Custom CloudWatch Metrics from Node.js on Elastic Beanstalk¶

This recipe shows how to publish custom CloudWatch metrics from an Express application by using AWS SDK v3. It helps you track app-specific behavior such as orders created, jobs queued, or cache misses.

Prerequisites¶

Running Node.js Elastic Beanstalk environment.
IAM permission for cloudwatch:PutMetricData.
@aws-sdk/client-cloudwatch installed.

What You'll Build¶

You will build an Express endpoint that publishes a custom metric to CloudWatch when a tracked action occurs.

flowchart LR
    A[Express App on Elastic Beanstalk] --> B[EC2 Instance Profile]
    B --> C[Amazon CloudWatch]
    C --> D[Custom Metric Namespace]

Steps¶

Step 1: Install the CloudWatch client¶

npm install @aws-sdk/client-cloudwatch

Step 2: Add a metric namespace in environment properties¶

aws elasticbeanstalk update-environment \
    --application-name "$APP_NAME" \
    --environment-name "$ENV_NAME" \
    --option-settings Namespace=aws:elasticbeanstalk:application:environment,OptionName=CW_NAMESPACE,Value="$APP_NAME/Application" \
    --region "$REGION"

Step 3: Publish a metric from the application¶

const express = require("express");
const {
    CloudWatchClient,
    PutMetricDataCommand
} = require("@aws-sdk/client-cloudwatch");

const app = express();
const client = new CloudWatchClient({ region: process.env.AWS_REGION });

app.post("/orders", async (req, res) => {
    await client.send(new PutMetricDataCommand({
        Namespace: process.env.CW_NAMESPACE,
        MetricData: [
            {
                MetricName: "OrdersCreated",
                Unit: "Count",
                Value: 1,
                Dimensions: [
                    { Name: "EnvironmentName", Value: process.env.ENV_NAME }
                ]
            }
        ]
    }));

    res.status(202).json({ status: "metric-published" });
});

Step 4: Add the environment name as an environment property¶

aws elasticbeanstalk update-environment \
    --application-name "$APP_NAME" \
    --environment-name "$ENV_NAME" \
    --option-settings Namespace=aws:elasticbeanstalk:application:environment,OptionName=ENV_NAME,Value="$ENV_NAME" \
    --region "$REGION"

Step 5: Deploy and trigger the metric¶

eb deploy --staged
curl --request POST "http://$CNAME/orders"

Verification¶

aws cloudwatch list-metrics \
    --namespace "$APP_NAME/Application" \
    --region "$REGION"

Expected result: CloudWatch lists the OrdersCreated metric after the route is called.

Clean Up¶

Remove the custom metric publishing path and related IAM permission if you no longer need the integration. Old custom metrics expire automatically when data stops arriving.

See Also¶

Sources¶