Inherit from TargetWithContext and use NLog Layouts

[snakefoot]

Updated to use the TargetWithContext that makes it easier to capture NLog-context:

• See also: https://github.com/NLog/NLog/wiki/How-to-write-a-custom-target-for-structured-logging

Replaced the following properites with ArrayParameter:

• Resources
• Attributes

Change the following properties to use NLog Layout (Allow target-configuration using ${configsetting})

• Layout - Instead of LogEventInfo.FormattedMessage. Default: ${message}
• EndPoint
• Headers
• UseHttp
• ScheduledDelayMilliseconds
• UseDefaultResources
• IncludeFormattedMessage

Added the following new properties:

• MaxQueueSize
• MaxExportBatchSize
• IncludeEventProperties - Inherited from TargetWithContext. Default: true
• IncludeScopeProperties - Inherited from TargetWithContext. Default: false
• IncludeEventParameters. Default: false

[snakefoot]

But really weird that one have to go through LogRecordData to be able to publish the actual LogRecord.

Because of this translation, then one suddenly looses the ability to assign properties:

• LogRecord.CategoryName (Same as NLog Logger-Name)

  For now, CategoryName is no longer exported via OTLP. It will be reintroduced in the future as an attribute.

• LogRecord.Exception

  Seems LogRecordAttributeList.RecordException is the work-around.

[juliuskoval]

Hi so the thing is that OpenTelemetry logging was originally made to work with Microsoft's ILogger and I'm using the bridge API, which is supposed to connect OpenTelemetry logging to existing logging frameworks. This API is only intended for backend developers, so it kind of feels like an afterthought. It also isn't stable yet.

I created a pull request which would allow us to set CategoryName, but it was denied.

Out of curiosity, how did you find the repo so quickly?

[snakefoot]

Out of curiosity, how did you find the repo so quickly?

I sometimes use GitHub-Repository-search to check for new interesting NLog extensions. The "OpenTelemetryProtocol" caught my eye, as others have requested such an integration: https://github.com/NLog/NLog/issues/5352

[snakefoot]

I created a https://github.com/open-telemetry/opentelemetry-dotnet/pull/5275 which would allow us to set CategoryName, but it was denied.

If they accept that the Logger-name is mapped to Category-Name. Then I guess this NLog Target could maintain a dictionary of OpenTelemetry-Loggers. And lookup/create Logger based on LogEventInfo.Logger-string-value.

[juliuskoval]

Yes, that's what I was thinking. Something like this https://github.com/dotnet/runtime/blob/e3ff66bf5afdcb85a642e69962ed5f6575751a35/src/libraries/Microsoft.Extensions.Logging/src/LoggerFactory.cs#L139

[juliuskoval]

Alright, the PR looks good. Thank you for the contribution.