[API Proposal]: Enhance LoggerMessage attribute to support logging complex object and redaction #81730
Description
Background and motivation
.NET uses source generation to provide high performance logging via LoggerMessage attribute. Source generation opens up a lot of flexibility to do more things in an efficient manner. We have a telemetry solution that is used by services across our orgs, as part of our solution we have expanded the LoggerMessage to support the following features
- Logging of complex object i.e. If you have an object let's say ErrorDetails and developer needs to log the details of the error. Today it is achieved by individually logging all members of the object e.g.
logger.Log("Failed to fetch data due to error: {0}, {1}, {2}", errorDetails.operationId, errorDetails.Type, errorDetails.Message);. Instead with the support of complex object logging in LoggerMessage attribute developer can log the object directly i.e.logger.DataFetchFailed(errorDetails). This will perform the expansion of the errorDetails object as part of the compile time source generation in an efficient way (i.e. no runtime cost) - Redacting sensitive data: Services has need to not log sensitive data in telemetry. Today developers need to redact the data before the information is logged and in order to redact the data they need to know which fields are redacted and copy over the logic to redact it. Often times the redaction is not done in a performant way.
API Proposal
Introduce LogPropertiesAttribute which is used to annotate an object that needs to be expanded for logging.
[AttributeUsage(AttributeTargets.Parameter)]
[Conditional("CODE_GENERATION_ATTRIBUTES")]
public sealed class LogPropertiesAttribute : Attribute
{
...
}API Usage
public class Operation
{
public string Id {get; set;}
public string Name {get; set;}
}
public class ErrorDetails
{
public Operation Operation {get; set;}
public ErrorType Type {get; set;}
public string ErrorMessage {get; set;}
}
public static partial class Log
{
[LoggerMessage(
EventId = 0,
Level = LogLevel.Error,
Message = "Could not open socket")]
public static partial void CouldNotOpenSocket(
this ILogger logger, [LogProperties] error);
}
// log the error
var errorDetails = ...
logger.CouldNotOpenSocket(error);This will result in all parameters of the error details logged as error_Operation_Id, error_Operation_Name, error_Type, error_ErrorMessage.
This is a simplistic example. LogProperties can have parameters that extends its functionality with more options.
The above can be augmented via some attributes to indicate sensitive data so the generated code takes care of redacting it appropriately.
public static partial class Log
{
[LoggerMessage(
EventId = 0,
Level = LogLevel.Information,
Message = "Fetching profile failed for {user}")]
public static partial void ProfileFetchFailed(
this ILogger logger, IRedactorProvider redactorProvider, [XYZ] user); // XYZ here is a placeholder for the data classification attribute, I am intentionally omitting the real attributes
}
// Generated code will use redactorProvider to redact the `userId` according to the data class XYZ
// Usage is
logger.ProfileFetchFailed(redactorProvider, userId);Similarly the attribute XYZ can be added to the members of the complex object and the generated code should be able to know and redact it.
Alternative Designs
No response
Risks
No response