Feature request: Add InnerException to Exceptions' structured log

[joaope]

Use case

Hi!

Current implementation leads to logged exceptions to loose valuable information, in particular their inner exceptions. Only Message, Source and StackTrace are being added to the final structured log.

For the following:

Logger.LogError(
    new InvalidOperationException("Parent exception message",
        new ArgumentNullException(nameof(input), "Very important inner exception message")), 
    "Something went wrong and we logged an exception itself with an inner exception. This is a param {arg}",
    12345);

We will see this, with the very important inner exception being lost forever:

{
    "...",
    "timestamp": "2024-12-05T13:29:34.9150895Z",
    "level": "Error",
    "service": "DotnetAotFunction",
    "name": "DotnetAotFunction",
    "message": "Something went wrong and we logged an exception itself with an inner exception. This is a param 12345",
    "exception": {
        "type": "System.InvalidOperationException",
        "message": "parent exception message"
    }
}

Solution/User Experience

Given InnerException is itself a property of the base Exception class, adding support to also structure log it seems pretty trivial.

For the above I would expect this instead:

{
    "...",
    "timestamp": "2024-12-05T13:29:34.9150895Z",
    "level": "Error",
    "service": "DotnetAotFunction",
    "name": "DotnetAotFunctionr",
    "message": "Something went wrong and we logged an exception itself with an inner exception. This is a param 12345",
    "exception": {
        "type": "System.InvalidOperationException",
        "message": "Parent exception message",
        "inner_exception": {
            "type": "System.ArgumentNullException",
            "message": "Very important inner exception message"
        }
    }
}

Obviously the example is for a single child inner exception but, given the serialization is recursive, this would be also be working for inner exceptions within inner exceptions, until the end of the exceptions' tree branch.

Happy to contribute a PR for this, if accepted.

Thanks!

Alternative solutions

N/A

Acknowledgment

• This feature request meets Powertools for AWS Lambda (.NET) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and TypeScript

[boring-cyborg]

Thanks for opening your first issue here! We'll come back to you as soon as we can.
In the meantime, check out the #dotnet channel on our Powertools for AWS Lambda Discord: Invite link

[hjgraca]

Hi @joaope thanks for opening the issue. You are correct that should be part of the exception. I need a couple of days to understand why is not available in the first place, hopefully is a simple addition to the logs. Will keep you posted.
Thanks again