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Publish Custom CloudWatch Metrics from Python on Elastic Beanstalk¶

This recipe shows how to publish application-specific metrics from Flask to Amazon CloudWatch. It helps you monitor business events or internal workload signals that Elastic Beanstalk health metrics do not expose.

Prerequisites¶

Running Python Elastic Beanstalk environment.
IAM permission for cloudwatch:PutMetricData.
CloudWatch monitoring and alerting workflow defined for the metric.

What You'll Build¶

You will build a Flask endpoint that publishes a custom metric to CloudWatch whenever the application processes a tracked action.

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

Steps¶

Step 1: Grant the instance profile permission to publish metrics¶

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "cloudwatch:PutMetricData",
            "Resource": "*"
        }
    ]
}

Step 2: Define 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 metrics from Flask with boto3¶

import os

import boto3
from flask import Flask

application = Flask(__name__)
cloudwatch = boto3.client("cloudwatch")


@application.post("/orders")
def create_order():
    cloudwatch.put_metric_data(
        Namespace=os.environ["CW_NAMESPACE"],
        MetricData=[
            {
                "MetricName": "OrdersCreated",
                "Unit": "Count",
                "Value": 1,
                "Dimensions": [
                    {"Name": "EnvironmentName", "Value": os.environ["ENV_NAME"]}
                ]
            }
        ]
    )
    return {"status": "metric-published"}, 202

Step 4: Expose the environment name to the application¶

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 exercise the metric path¶

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 application route is invoked.

Clean Up¶

Remove the code path or metric publishing policy if you no longer need the metric. Custom metrics age out automatically when no new data points are published.

See Also¶

Sources¶