> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Create a Canary Function using Blueprint
> Learn to deploy a Canary Function in AWS Lambda using a blueprint, configure triggers, environment variables, and monitor with logs and metrics.
Learn how to deploy a Canary Function in AWS Lambda with a ready-made blueprint. In this guide, you’ll use Amazon EventBridge (CloudWatch Events) as a trigger, configure environment variables, set up SNS destinations for success and failure notifications, and monitor your function using logs and metrics.
• An AWS account with permissions to create Lambda functions, EventBridge rules, and SNS topics\
• Basic knowledge of Python and AWS services
## Table of Contents
1. [Open the Lambda Console](#1-open-the-lambda-console)
2. [Select the Canary Blueprint](#2-select-the-canary-blueprint)
3. [Configure the Function](#3-configure-the-function)
4. [Review the Sample Code](#4-review-the-sample-code)
5. [Set Schedule & Environment Variables](#5-set-schedule--environment-variables)
6. [View Your New Function](#6-view-your-new-function)
7. [Add SNS Destinations for Success & Failure](#7-add-sns-destinations-for-success--failure)
8. [Test the Canary Function](#8-test-the-canary-function)
9. [Monitor Metrics and Logs](#9-monitor-metrics-and-logs)
***
## 1. Open the Lambda Console
1. Sign in to the [AWS Management Console](https://aws.amazon.com/console/).
2. In the **Services** menu, search for **Lambda** and click **Lambda**.
3. Choose **Create function**.
## 2. Select the Canary Blueprint
AWS provides several blueprints with boilerplate code for common tasks. In the **Use a blueprint** tab:
* Search for **canary**.
* Select **Canary Function** (runtime: **Python 3.7**).
This blueprint periodically checks a URL for a specified text string.
## 3. Configure the Function
1. Click **Configure**.
2. Enter a **Function name**, e.g., `KodeKloudCanaryDemo`.
3. Under **Permissions**, select **Create a new role with basic Lambda permissions**.
EventBridge is already set as the trigger. Create a new rule:
* **Rule name**: `CanaryDemoRule`
## 4. Review the Sample Code
Scroll to **Function code** to inspect the handler:
```python theme={null}
import os
from datetime import datetime
from urllib.request import Request, urlopen
SITE = os.environ['site'] # URL to check
EXPECTED = os.environ['expected'] # Expected text on the page
def validate(response):
"""
Return True if EXPECTED appears in the content.
Extend this for custom checks.
"""
return EXPECTED in response
def lambda_handler(event, context):
print(f"Checking {SITE} at {event['time']}")
try:
req = Request(SITE, headers={'User-Agent': 'AWS Lambda'})
content = urlopen(req).read().decode('utf-8')
if not validate(content):
raise Exception('Validation failed')
print('Check passed')
except Exception as e:
print('Check failed:', e)
raise
```
This uses two environment variables:
| Variable | Description |
| ---------- | ------------------------- |
| `site` | URL of the site to check |
| `expected` | Text string to search for |
## 5. Set Schedule & Environment Variables
1. In the trigger pane, set the **Schedule expression** to:
```text theme={null}
rate(1 minute)
```
2. Under **Variables and secrets**, add:
| Key | Value |
| ---------- | -------------------------------------------- |
| `site` | `https://kodekloud.com` |
| `expected` | a string *not* on the site (to test failure) |
When ready, click **Create function**. AWS will provision the new function.
## 6. View Your New Function
After creation, the Lambda console displays your function’s details and trigger.
## 7. Add SNS Destinations for Success & Failure
By default, asynchronous invocations don’t return errors to the trigger. To capture outcomes:
1. Click **Add destination**.
2. Under **Source type**, select **Asynchronous invocation**.
3. Set **Condition** to **On failure**.
4. For **Destination type**, choose **SNS topic** and pick (or create) your topic, e.g., `Canary Demo Failures`.
5. Save and allow AWS to create the necessary IAM role.
Repeat to add an **On success** destination to an SNS topic (e.g., `Canary Demo Success`).
Once done, both destinations will appear alongside your EventBridge rule.
## 8. Test the Canary Function
1. In the Lambda console, click **Test**.
* The first invocation should fail (expected=string not on site).
2. To simulate success, go to **Configuration > Variables and secrets** and update `expected` to a word you know exists (e.g., `learned`).
3. Save and click **Test** again.
Now the function should pass the validation.
## 9. Monitor Metrics and Logs
To review invocation metrics:
1. Click the **Monitor** tab in the Lambda console.
2. For detailed logs, select **View logs in CloudWatch**.\
Inspect each log stream to see both failures and successful runs.
***
Congratulations! You’ve successfully created a Canary Function using an AWS Lambda blueprint, scheduled it with EventBridge, configured SNS destinations, and monitored its behavior. For more AWS Lambda tips and tutorials, explore the [AWS Lambda Documentation](https://docs.aws.amazon.com/lambda/latest/dg/welcome.html).