Skip handling of container image lambda functions

[duncanpharvey]

What does this PR do?

Skip handling of container image Lambda functions. Lambda functions packaged into container images are instrumented with Datadog differently than Lambda functions packaged into a zip. The CloudFormation Macro should not make any changes to these container image Lambda functions.

Motivation

https://github.com/DataDog/datadog-cloudformation-macro/issues/108

Testing Guidelines

Created a SAM template with a zip Lambda function and container image Lambda function. Verified that (1) the zip Lambda function is instrumented with the CloudFormation Macro and sends metrics, logs, and traces to Datadog and (2) the container image Lambda function is unaffected by the CloudFormation Macro and sends metrics, logs, and traces to Datadog.

template.yaml

AWSTemplateFormatVersion: "2010-09-09"
Transform:
  - AWS::Serverless-2016-10-31
  - Name: DatadogServerlessTest
    Parameters:
      stackName: !Ref "AWS::StackName"
      apiKey: <redacted>
      pythonLayerVersion: "87"
      extensionLayerVersion: "52"

Globals:
  Function:
    Timeout: 10
    MemorySize: 256
    Architectures:
      - x86_64

Resources:
  HelloWorldFunctionContainer:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      Environment:
        Variables:
          DD_LAMBDA_HANDLER: app.lambda_handler
          DD_API_KEY: <redacted>
          DD_SITE: datadoghq.com
          DD_TRACE_ENABLED: true
    Metadata:
      Dockerfile: Dockerfile
      DockerContext: ./hello_world
      DockerTag: python3.9-v1
  HelloWorldFunctionZip:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.9

Dockerfile

FROM public.ecr.aws/lambda/python:3.9

COPY requirements.txt ./
RUN python3.9 -m pip install -r requirements.txt -t .

COPY app.py ./

COPY --from=public.ecr.aws/datadog/lambda-extension:latest /opt/extensions/ /opt/extensions

CMD ["datadog_lambda.handler.handler"]

Additional Notes

Types of changes

• [x] Bug fix
• [ ] New feature
• [ ] Breaking change
• [ ] Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• [x] This PR's description is comprehensive
• [ ] This PR contains breaking changes that are documented in the description
• [ ] This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• [ ] This PR impacts documentation, and it has been updated (or a ticket has been logged)
• [x] This PR's changes are covered by the automated tests
• [ ] This PR collects user input/sensitive content into Datadog

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (443c298) 84.62% compared to head (fb7f505) 84.70%.

:exclamation: Current head fb7f505 differs from pull request most recent head cf9e13a. Consider uploading reports for the commit cf9e13a to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #119 +/- ## ========================================== + Coverage 84.62% 84.70% +0.07% ========================================== Files 8 8 Lines 631 634 +3 Branches 158 159 +1 ========================================== + Hits 534 537 +3 Misses 85 85 Partials 12 12 ```

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