feat: Powertools User-Agent for Lambda execution environment

[hjgraca]

Issue number: #213

Summary

Update the execution environment so that the appropriate metadata can be attached to the user agent string during service calls via the AWS SDK for .NET

Changes

• Add method to set context in PowertoolsConfigurations.cs.
• New PowertoolsEnvironment interface as a facade for System.Environment. Makes it testable
• Context naming convention for Utilities PTFeature/Name/Version
• Call SetExecutionEnvironment from Metrics, Tracing and Logging utilities
• This method is called with the Type and uses reflection to get the Name and Version of the calling Assembly
• Many more tests

New method to set the execution environment in the AWS.Lambda.Powertools.Common project

public void SetExecutionEnvironment<T>(T type)
{
    const string envName = "AWS_EXECUTION_ENV";

    var envValue = new StringBuilder();

    // If there is an existing execution environment variable add the annotations package as a suffix.
    if(!string.IsNullOrEmpty(GetEnvironmentVariable(envName)))
    {
        envValue.Append($"{GetEnvironmentVariable(envName)} ");
    }

    var assemblyVersion = _powertoolsEnvironment.GetAssemblyVersion(type);
    var assemblyName =_powertoolsEnvironment.GetAssemblyName(type);

    envValue.Append($"{ParseAssemblyName(assemblyName)}/{assemblyVersion}");

    SetEnvironmentVariable(envName, envValue.ToString());
}

Each Utility will have to Set the execution context

_powertoolsConfigurations.SetExecutionEnvironment(this);

User experience

User-Agent header is updated and includes the Utilities used in the request to an AWS service using AWS SDK

Checklist

Please leave checklist items unchecked if they do not apply to your change.

• Meets tenets criteria
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

RFC issue number:

Checklist:

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

Acknowledgment

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[codecov-commenter]

Codecov Report

Patch coverage: 88.73% and project coverage change: +3.99 🎉

Comparison is base (8bb7863) 56.29% compared to head (418c005) 60.29%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #246      +/-   ##
===========================================
+ Coverage    56.29%   60.29%   +3.99%     
===========================================
  Files           41       42       +1     
  Lines         1796     1851      +55     
===========================================
+ Hits          1011     1116     +105     
+ Misses         785      735      -50     

Flag	Coverage Δ
unittests	60.29% <88.73%> (+3.99%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...AWS.Lambda.Powertools.Common/Core/SystemWrapper.cs	75.55% <84.37%> (+75.55%)	⬆️
...Lambda.Powertools.Tracing/Internal/XRayRecorder.cs	95.83% <90.00%> (+95.83%)	⬆️
...da.Powertools.Common/Core/PowertoolsEnvironment.cs	92.85% <92.85%> (ø)
...Powertools.Common/Core/PowertoolsConfigurations.cs	91.42% <100.00%> (+19.55%)	⬆️
...da.Powertools.Logging/Internal/PowertoolsLogger.cs	91.07% <100.00%> (+0.05%)	⬆️
...aries/src/AWS.Lambda.Powertools.Metrics/Metrics.cs	84.37% <100.00%> (+0.12%)	⬆️

... and 1 file with indirect coverage changes

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[sliedig]

Waiting on confirmation from SDK team

[normj]

The approach looks good to me. I just added a couple comments to confirm behavior.

[normj]

I don't know the whole system so it might already being doing this but make sure this is only called once per power tools assembly. These assembly look up calls are can be costly and we don't want to it for every request.

[hjgraca]

Thanks for the feedback @normj . The implementation prevents multiple instances of SystemWrapper to be created. The instances that create systemwrapper are singletons. The constructors are called once for the lambda lifetime.

[amirkaws]

LGTM

[amirkaws]

This one calls SystemWrapper. SetExecutionEnvironment and the system Wrapper I believe calls PowertoolsEnvironment, I believe there are too many layers of abstractions.