# AWS Lambda to AWS CloudWatch

This SAM template deploys a Lambda function that inserts custom metric data into AWS Cloudwatch. The AWS SAM template deploys the resources and the IAM permissions required to run the application.

Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/lambda-cloudwatch.

Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the [AWS Pricing page](https://aws.amazon.com/pricing/) for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.

## Requirements

* [Create an AWS account](https://portal.aws.amazon.com/gp/aws/developer/registration/index.html) if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
* [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) installed and configured
* [Git Installed](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
* [AWS Serverless Application Model](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install.html) (AWS SAM) installed

## Deployment Instructions

1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:
    ``` 
    git clone https://github.com/aws-samples/serverless-patterns
    ```
1. Change directory to the pattern directory:
    ```
    cd lambda-cloudwatch
    ```
1. From the command line, use AWS SAM to deploy the AWS resources for the pattern as specified in the template.yml file:
    ```
    sam deploy --guided
    ```
1. During the prompts:
    * Enter a stack name
    * Enter the desired AWS Region
    * Allow SAM CLI to create IAM roles with the required permissions.

    Once you have run `sam deploy --guided` mode once and saved arguments to a configuration file (samconfig.toml), you can use `sam deploy` in future to use these defaults.

1. Note the outputs from the SAM deployment process. These contain the resource names and/or ARNs which are used for testing.

## How it works

The Lambda function takes values from the invocation event and inserts them as custom metric data in AWS Cloudwatch.

Event will pass the following:
* type - Data type you want to insert as a custom metric (JSON data type: string)
* value - Data value (JSON data type: number)

## Testing

1. You can test the solution by accessing the Lambda console, finding the Lambda function, and clicking Test in the Code Source section.

2. Create a new test event and supply the example event.

Example Event
```
{
  "type": "1",
  "value": 1
}
```

3. After invoking the function with the test event, verify metric data in the Cloudwatch console through Metrics -> All Metrics -> Custom Namespaces -> ExampleNamespace.

## Cleanup
 
1. Delete the stack
    ```bash
    aws cloudformation delete-stack --stack-name STACK_NAME
    ```
1. Confirm the stack has been deleted
    ```bash
    aws cloudformation list-stacks --query "StackSummaries[?contains(StackName,'STACK_NAME')].StackStatus"
    ```
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