docs: provide a sample iam policy

[Nr18]

Issue #, if available: N/A

Description of changes:

The AWS::Serverless::Function resource will give the proper IAM policies for the logger and tracing automatically but you need to provide an additional policy if you want to make use of the Metrics utility.

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

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[codecov-commenter]

Codecov Report

Merging #91 into develop will not change coverage.
The diff coverage is n/a.

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[nmoutschen]

Hey Joris!

Where/when would this policy be needed? The Powertools use EMF to create metrics, so as long as the function can emit logs, this should work.

[Nr18]

@nmoutschen ah I see 🤔 I will retest I did not see any metrics until I added the policy.

I will get back to you on this one

[nmoutschen]

I just checked on the permissions from the CreateOrder function in the aws-serverless-ecommerce-platform sample and it only has permissions for logs, X-Ray, API Gateway and DynamoDB.

By the way, have you decorated the handler with @metrics.log_metrics? It happened to me when I made the switch to Powertools for metrics. 😅

[Nr18]

Right I added the decorator around the same time I added the IAM policy 😆 , I will close the issue!